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Appl. Microbiol., Volume 4, Issue 2 (June 2024) – 28 articles

Cover Story (view full-size image): Applied Microbiology (ISSN 2673-8007) provides an advanced forum for studies related to the application of microorganisms, with a strong emphasis on biotechnology, environment, medicine, and food. It publishes original scientific research articles, comprehensive reviews, comments, commentaries, perspectives, etc. Our aim is to encourage scientists to publish their experimental and theoretical results in as much detail as possible. There is no restriction on the maximum length of the papers. The full experimental details must be provided so that the results can be reproduced. Electronic files and software regarding the full details of the calculation or experimental procedure, if unable to be published in a normal way, can be deposited as supplementary electronic material.
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14 pages, 883 KiB  
Review
Changes in the Skin Microbiome Following Dermatological Procedures: A Scoping Review
by Jeremy R. Ellis, Eron J. Powell, Luke M. Tomasovic, Rachel L. Marcheskie, Vishruth Girish, Anmol Warman and Darshan Sivaloganathan
Appl. Microbiol. 2024, 4(2), 972-985; https://doi.org/10.3390/applmicrobiol4020066 - 18 Jun 2024
Viewed by 707
Abstract
The skin microbiome consists of bacteria, fungi, viruses, and mites, which play a crucial role in maintaining skin health and immune function. Imbalances in this microbial community, known as dysbiosis, are implicated in various dermatological conditions. While skincare products are known to influence [...] Read more.
The skin microbiome consists of bacteria, fungi, viruses, and mites, which play a crucial role in maintaining skin health and immune function. Imbalances in this microbial community, known as dysbiosis, are implicated in various dermatological conditions. While skincare products are known to influence the skin microbiome, the effects of dermatological procedures have not been extensively studied. Here, we perform a scoping review to outline the studies investigating the impacts of dermatological interventions on the skin microbiome. Phototherapy emerged as the most studied intervention, encompassing UV phototherapy, light therapy, laser therapy, and photodynamic therapy. Chemical interventions, such as chemical peels, micropigmentation, and debridement, have comparatively limited studies describing their impacts on the skin microbiome. To date, no studies have been done on a wide variety of common dermatological procedures such as cryotherapy, skin grafts, and dermabrasion, which may have stronger likelihoods of affecting the skin microbiome. This underscores the need for further research on the influences of dermatological procedures, especially chemical and physical interventions, on the skin microbiome. More comprehensive pre-clinical and clinical studies are essential not only for understanding the long-term consequences of these procedures, but also for optimizing patient outcomes in dermatological care. Full article
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13 pages, 1679 KiB  
Article
Valorisation of Spent Yeast Fermentation Media through Compositional-Analysis-Directed Supplementation
by Laura Murphy, Ciara D. Lynch and David J. O’Connell
Appl. Microbiol. 2024, 4(2), 959-971; https://doi.org/10.3390/applmicrobiol4020065 - 12 Jun 2024
Viewed by 723
Abstract
Spent fermentation media from bioprocessing represent a significant waste stream, and interest in recycling them as part of the developing circular bioeconomy is growing. The potential to reuse yeast spent culture media (YSM) to feed secondary bacterial fermentations producing recombinant protein was investigated [...] Read more.
Spent fermentation media from bioprocessing represent a significant waste stream, and interest in recycling them as part of the developing circular bioeconomy is growing. The potential to reuse yeast spent culture media (YSM) to feed secondary bacterial fermentations producing recombinant protein was investigated in this study. Elemental and amino acid compositional analysis using inductively coupled plasma mass spectrometry (ICP-MS) and LC-MS/MS identified significant differences in the concentrations of 6 elements and 18/20 amino acids in YSM compared with rich microbiological media (LB). Restoration of levels of magnesium and sodium through addition of their salts and amino acids from tryptone supplementation led to the expression of equivalent titres of recombinant proteins by E. coli (0.275 g/L), compared to that in LB media (0.296 g/L) and BMMY media (0.294 g/L) in shake flask culture. When this supplementation strategy was employed in a bioreactor system, we observed a significant increase in recombinant protein titre using the supplemented YSM (2.29 (±0.02) g/L) over that produced using LB media (1.29 (±0.09) g/L). This study demonstrates through highly sensitive compositional analysis and identification of supplementation strategies the potential to valorise spent media from yeast fermentations that underpin industrial processes of significant scale, creating a circular approach to waste stream management. Full article
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11 pages, 1567 KiB  
Article
Predicting Microbiome Growth Dynamics under Environmental Perturbations
by George Sun and Yi-Hui Zhou
Appl. Microbiol. 2024, 4(2), 948-958; https://doi.org/10.3390/applmicrobiol4020064 - 10 Jun 2024
Viewed by 582
Abstract
MicroGrowthPredictor is a model that leverages Long Short-Term Memory (LSTM) networks to predict dynamic changes in microbiome growth in response to varying environmental perturbations. In this article, we present the innovative capabilities of MicroGrowthPredictor, which include the integration of LSTM modeling with a [...] Read more.
MicroGrowthPredictor is a model that leverages Long Short-Term Memory (LSTM) networks to predict dynamic changes in microbiome growth in response to varying environmental perturbations. In this article, we present the innovative capabilities of MicroGrowthPredictor, which include the integration of LSTM modeling with a novel confidence interval estimation technique. The LSTM network captures the complex temporal dynamics of microbiome systems, while the novel confidence intervals provide a robust measure of prediction uncertainty. We include two examples—one illustrating the human gut microbiota composition and diversity due to recurrent antibiotic treatment and the other demonstrating the application of MicroGrowthPredictor on an artificial gut dataset. The results demonstrate the enhanced accuracy and reliability of the LSTM-based predictions facilitated by MicroGrowthPredictor. The inclusion of specific metrics, such as the mean square error, validates the model’s predictive performance. Our model holds immense potential for applications in environmental sciences, healthcare, and biotechnology, fostering advancements in microbiome research and analysis. Moreover, it is noteworthy that MicroGrowthPredictor is applicable to real data with small sample sizes and temporal observations under environmental perturbations, thus ensuring its practical utility across various domains. Full article
(This article belongs to the Special Issue Microbiome in Ecosystem 3.0)
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14 pages, 2841 KiB  
Article
Evaluation of Solid-State Fermentation Conditions from Pineapple Peel Waste for Release of Bioactive Compounds by Aspergillus niger spp.
by A. Danitza Casas-Rodríguez, Juan A. Ascacio-Valdés, Miriam Desirée Dávila-Medina, Miguel A. Medina-Morales, Liliana Londoño-Hernández and Leonardo Sepúlveda
Appl. Microbiol. 2024, 4(2), 934-947; https://doi.org/10.3390/applmicrobiol4020063 - 8 Jun 2024
Viewed by 877
Abstract
Currently, agroindustrial waste can be used to obtain bioactive compounds. The solid-state fermentation is an alternative for the valorization of these waste and to be able to release bioactive compounds that may be of interest to different industrial sectors. The aim of this [...] Read more.
Currently, agroindustrial waste can be used to obtain bioactive compounds. The solid-state fermentation is an alternative for the valorization of these waste and to be able to release bioactive compounds that may be of interest to different industrial sectors. The aim of this study was to evaluate solid-state fermentation conditions using pineapple peel waste as the substrate with Aspergillus niger spp., to release bioactive compounds using a Plackett–Burman exploratory design. Temperature, humidity, inoculum, NaNO3, MgSO4, KCl, and KH2PO4 conditions in the fermentation process were evaluated. The antioxidant capacity was determined, and the main compounds of the fermentation extracts were identified. The results revealed that the Aspergillus niger HT3 strain reached a hydrolyzable tannin release of 10.00 mg/g, While Aspergillus niger Aa20 reached a condensed tannin release of 82.59 mg/g. The KH2PO4 affects the release of condensed tannins with A. niger Aa20, and MgSO4 affects the release of hydrolyzable tannins with A. niger HT3. In addition, a positive antioxidant activity was demonstrated for the DPPH, ABTS, and FRAP technique. The main compounds in the fermented pineapple peel were 3-feruloylquinic acid, caffeic acid, lariciresinol, and 3-hydroxyphloretin 2′-O-xylosyl-glucoside, among others. The solid-state fermentation process is a biotechnological alternative for the release of bioactive compounds. Full article
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16 pages, 2549 KiB  
Article
16S rRNA Analysis of Electrogenic Bacterial Communities from Soil Microbial Fuel Cells
by Ana Rumora, Liliana Hopkins, Kayla Yim, Melissa F. Baykus, Luisa Martinez and Luis Jimenez
Appl. Microbiol. 2024, 4(2), 918-933; https://doi.org/10.3390/applmicrobiol4020062 - 5 Jun 2024
Viewed by 521
Abstract
Electrogenic bacteria present in bioelectrical devices such as soil microbial fuel cells (SMFCs) are powered by the oxidation of organic and inorganic compounds due to microbial activity. Fourteen soils randomly selected from Bergen Community College or areas nearby, located in the state of [...] Read more.
Electrogenic bacteria present in bioelectrical devices such as soil microbial fuel cells (SMFCs) are powered by the oxidation of organic and inorganic compounds due to microbial activity. Fourteen soils randomly selected from Bergen Community College or areas nearby, located in the state of New Jersey, USA, were used to screen for the presence of electrogenic bacteria. SMFCs were incubated at 35–37 °C. Of the 14 samples, 11 generated electricity and enriched electrogenic bacteria. The average optimal electricity production by the top 3 SMFCs was 152 microwatts. The highest electrical production was produced by SMFC-B1C and SMFC-B1B, with 162 and 152 microwatts, respectively. Microbial DNA was extracted from the biofilm grown on the anodes, followed by PCR analysis of the 16S rRNA V3–V4 region. Next-generation sequencing was performed to determine the structure and diversity of the electrogenic microbial community. The top 3 MFCs with the highest electricity production showed a bacterial community predominantly composed of bacteria belonging to the Bacillota and Pseudomonadota phyla with a significant presence of Euryarcheota members of methanogenic archaea. SMFC-B1C showed a more diverse electrogenic community, followed by SMFC-B1B and SMFC-B1. When analyzing the top 10 bacteria in the SMFCs, 67 percent belonged to the class Clostridia, indicating that anaerobic conditions were required to enrich electrogenic bacterial numbers and optimize electrical production. The ongoing optimization of SMFCs will provide better production of electricity and continuous enhancement of microbial activity to sustain longer operational times and higher levels of electrogenesis. The characterization of electrogenic microbial communities will provide valuable information to understand the contribution of different populations to the production of electricity in bioelectrical devices. Full article
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24 pages, 634 KiB  
Review
The Industrial Fermentation Process and Clostridium Species Used to Produce Biobutanol
by David T. Jones
Appl. Microbiol. 2024, 4(2), 894-917; https://doi.org/10.3390/applmicrobiol4020061 - 31 May 2024
Viewed by 382
Abstract
The fermentation route for producing biobutanol from renewable plant biomass was used extensively during the last century. The key factors affecting performance in the standard batch industrial fermentation process are highlighted. Four species of Clostridium were utilized for the industrial production of solvents, [...] Read more.
The fermentation route for producing biobutanol from renewable plant biomass was used extensively during the last century. The key factors affecting performance in the standard batch industrial fermentation process are highlighted. Four species of Clostridium were utilized for the industrial production of solvents, and although they share many features in common, they also exhibit significant differences. The salient features of the existing industrial species and strains are reviewed. These include their suitability for the type of process and fermentation substrate used. The strains are also assessed with respect to their potential for future applications. Full article
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19 pages, 1725 KiB  
Article
Trichoderma: Population Structure and Genetic Diversity of Species with High Potential for Biocontrol and Biofertilizer Applications
by Adnan Ismaiel, Dilip K. Lakshman, Prashant P. Jambhulkar and Daniel P. Roberts
Appl. Microbiol. 2024, 4(2), 875-893; https://doi.org/10.3390/applmicrobiol4020060 - 27 May 2024
Viewed by 465
Abstract
Certain Trichoderma isolates provide biofertilizer, biocontrol, and other plant-beneficial activities while inhabiting the soil or internal plant tissue, and their use in agricultural systems can contribute to sustainable food production. It is thought that colonization of soil or internal plant tissue is fundamental [...] Read more.
Certain Trichoderma isolates provide biofertilizer, biocontrol, and other plant-beneficial activities while inhabiting the soil or internal plant tissue, and their use in agricultural systems can contribute to sustainable food production. It is thought that colonization of soil or internal plant tissue is fundamental for biocontrol and biofertilizer applications. Our collective analyses of prior surveys, where the tef1α sequence was almost exclusively used to identify Trichoderma species, showed that isolates from the Harzianum complex clade, the T. asperellum/T. asperelloides group, T. virens, T. hamatum, and T. atroviride were prevalent in soil and/or as endophytes. Population structure and genetic diversity based on the genetic markers tef1α, rpb2, and ITS were investigated, and new lineages with statistical bootstrap support within T. atroviride, T. asperellum, T. hamatum, and T. virens populations were found. The nearest relatives of some of these species were also revealed. Choosing isolates from among more than 500 known Trichoderma species for use in non-targeted evaluation screens for biocontrol or biofertilizer applications is time-consuming and expensive. Preferentially selecting isolates from T. atroviride, T. asperellum/T. asperelloides, T. hamatum, the T. harzianum complex clade, T. virens, and possibly nearest relatives may speed the identification of candidates for commercialization due to the demonstrated ability of these species to successfully inhabit the soil and internal plant tissue. To our knowledge, this is the first report where dominant soil and endophytic Trichoderma species were identified from past survey data and population structure and genetic diversity analyses conducted. Full article
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19 pages, 3445 KiB  
Article
The Detection of Propionate Utilization by Bacteria Isolated from a Plastic Recycling Site
by Shuyan Wu, Pornchanok Subharat, Faith Palevich, John Mills and Gale Brightwell
Appl. Microbiol. 2024, 4(2), 856-874; https://doi.org/10.3390/applmicrobiol4020059 - 23 May 2024
Viewed by 665
Abstract
(1) The study aims to utilize a reported approach for culturing mesophilic bacteria from a plastic waste environment; (2) The work revived mesophilic microbial population from an aged PET recycling site using a culture-based approach, and determined the purified isolates in genus level [...] Read more.
(1) The study aims to utilize a reported approach for culturing mesophilic bacteria from a plastic waste environment; (2) The work revived mesophilic microbial population from an aged PET recycling site using a culture-based approach, and determined the purified isolates in genus level in 16S identification; (3) A total of 59 bacterial isolates were obtained, in which microbial species, including Pseudomonas spp, Rhodococcus spp, and Burkholderia spp were identified as abundance. It was observed that the surviving microbes favoured sodium propionate as a short-chain carbon source for growth, rather than the intended plastic substrate, PET. The preference of sodium propionate utilization by several bacterial isolates, including 5601W (detected as Rhodococcus spp.), 5601Y, 7801, and 7802 (detected as Burkholderia spp.), was confirmed through growth curve analysis and cell enumeration conducted in a medium where sodium propionate served as the sole carbon source.; (4) The microbial demonstration revealed the metabolic complex of microbial communities in the environment and indicated the challenges associated with bacterial isolation from environments with accumulated plastic waste. Full article
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17 pages, 4080 KiB  
Article
TRI14 Is Critical for Fusarium graminearum Infection and Spread in Wheat
by Guixia Hao, Robert H. Proctor, Daren W. Brown, Nicholas A. Rhoades, Todd A. Naumann, HyeSeon Kim, Santiago Gutiėrrez and Susan P. McCormick
Appl. Microbiol. 2024, 4(2), 839-855; https://doi.org/10.3390/applmicrobiol4020058 - 23 May 2024
Viewed by 863
Abstract
Trichothecenes are sesquiterpenoid toxins produced by diverse ascomycetes, including Fusarium. The trichothecene analog deoxynivalenol (DON) produced by the Fusarium head blight (FHB) pathogen Fusarium graminearum is a virulence factor on wheat and a major food and feed safety concern. In Fusarium, [...] Read more.
Trichothecenes are sesquiterpenoid toxins produced by diverse ascomycetes, including Fusarium. The trichothecene analog deoxynivalenol (DON) produced by the Fusarium head blight (FHB) pathogen Fusarium graminearum is a virulence factor on wheat and a major food and feed safety concern. In Fusarium, the trichothecene biosynthetic gene (TRI) cluster consists of 7–14 genes. Most TRI cluster genes are conserved and their specific roles in trichothecene biosynthesis have been determined. An exception is TRI14, which is not required for DON synthesis in vitro but is required for spread of F. graminearum in wheat heads. In the current study, gene expression analyses revealed that TRI14 was highly induced in infected wheat heads. We demonstrated that TRI14 was not only required for F. graminearum spread but also important for initial infection in wheat. Although a prior study did not detect DON in infected seeds, our analyses showed significantly less DON and fungal biomass in TRI14-mutant (designated ∆tri14)-inoculated heads than wild-type-inoculated heads. Gene expression comparison showed that the level of expression of TRI genes was similar in the wheat tissues infected with ∆tri14 or the wild type, indicating the reduced toxin levels caused by ∆tri14 may be due to less fungal growth. ∆tri14 also caused less lesion and grew less in wheat coleoptiles than the wild type. The growth of ∆tri14 in carboxymethylcellulose medium was more sensitive to hydrogen peroxide than the wild type. The data suggest that TRI14 plays a critical role in F. graminearum growth, and potentially protects the fungus from plant defense compounds. Full article
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15 pages, 1563 KiB  
Review
Reassessing Gout Management through the Lens of Gut Microbiota
by Jean Demarquoy and Oumaima Dehmej
Appl. Microbiol. 2024, 4(2), 824-838; https://doi.org/10.3390/applmicrobiol4020057 - 22 May 2024
Viewed by 687
Abstract
Gout, recognized as the most common form of inflammatory arthritis, arises from the accumulation of uric acid crystals, leading to intense pain, particularly in the big toe. This condition has traditionally been associated with the overproduction or reduced clearance of uric acid. Recent [...] Read more.
Gout, recognized as the most common form of inflammatory arthritis, arises from the accumulation of uric acid crystals, leading to intense pain, particularly in the big toe. This condition has traditionally been associated with the overproduction or reduced clearance of uric acid. Recent studies, however, have underscored the significant role of the gut microbiota in uric acid metabolism, impacting both its production and elimination. This emerging understanding suggests that maintaining gut health could offer innovative approaches to treating gout, complementing traditional dietary and pharmacological interventions. It highlights the potential of probiotics or microbiome-based therapies, indicating a future where treatments are tailored to an individual’s microbiome. This offers a fresh perspective on gout management and underscores the broader influence of the microbiota on health and disease. Full article
(This article belongs to the Special Issue Microbiome in Ecosystem 3.0)
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13 pages, 1475 KiB  
Article
Synergistic Effect of Postbiotic Yeast ABB C22® on Gut Inflammation, Barrier Function, and Protection from Rotavirus Infection in In Vitro Models
by Lydia Carrera Marcolin, Jordi Cuñé Castellana, Laia Martí Melero, Carlos de Lecea and Maria Tintoré Gazulla
Appl. Microbiol. 2024, 4(2), 811-823; https://doi.org/10.3390/applmicrobiol4020056 - 16 May 2024
Viewed by 706
Abstract
Diarrhoea is a serious cause of mortality worldwide that can lead to dehydration, gut barrier function impairment, nutrient malabsorption, and alterations of the gut microbiota (dysbiosis). The current solutions for its management, such as oral rehydration salts (ORS), inhibitors of gut motility, antibiotics, [...] Read more.
Diarrhoea is a serious cause of mortality worldwide that can lead to dehydration, gut barrier function impairment, nutrient malabsorption, and alterations of the gut microbiota (dysbiosis). The current solutions for its management, such as oral rehydration salts (ORS), inhibitors of gut motility, antibiotics, and living probiotics, only partially counteract the mechanisms of the disease and do not provide a full coverage of the problem. The potential risks of the use of living probiotic strains, particularly in immunocompromised patients, can be eliminated with the use of tyndallized (heat-killed) postbiotic bacteria and yeast. ABB C22® is a postbiotic combination of three tyndallized yeasts, namely Saccharomyces boulardii, Saccharomyces cerevisiae, and Kluyveromyces marxianus. To assess the action of the postbiotic combination on diarrhoea, immune and gut epithelial cell signalling assays, the gut barrier formation assay, and the rotavirus gene expression assay were performed. ABB C22® showed a strong anti-inflammatory effect, an induction of the build-up of the gut epithelium, and a degree of protection against rotavirus infection. These experimental studies support the use of the postbiotic ABB C22® as a solution for the management of diarrhoea and gastrointestinal conditions, alone or in combination with existing but incomplete treatments. Full article
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17 pages, 2567 KiB  
Review
Genetic Engineering of Filamentous Fungi: Prospects for Obtaining Fourth-Generation Biological Products
by Lorena Resende Oliveira, Ariany Rosa Gonçalves, Eliane Dias Quintela, Leandro Colognese, Marcio Vinicius de C. Barros Cortes and Marta Cristina Corsi de Filippi
Appl. Microbiol. 2024, 4(2), 794-810; https://doi.org/10.3390/applmicrobiol4020055 - 13 May 2024
Viewed by 851
Abstract
Filamentous fungi exhibit unparalleled potential as cell factories for protein production, owing to their adeptness in protein secretion and remarkable proficiency in post-translational modifications. This review delineates the role of filamentous fungi in bio-input technology across different generations and explores their capacity to [...] Read more.
Filamentous fungi exhibit unparalleled potential as cell factories for protein production, owing to their adeptness in protein secretion and remarkable proficiency in post-translational modifications. This review delineates the role of filamentous fungi in bio-input technology across different generations and explores their capacity to generate secondary metabolites. Our investigation highlights filamentous fungi as frontrunners in the production of bioactive compounds, emphasizing the imperative nature of elucidating their metabolic repertoire. Furthermore, we delve into common strategies for genetic transformation in filamentous fungi, elucidating the underlying principles, advantages, and drawbacks of each technique. Taking a forward-looking approach, we explore the prospects of genome engineering, particularly the CRISPR-Cas9 technique, as a means to propel protein secretion in filamentous fungi. Detailed examination of the protein secretion pathways in these fungi provides insights into their industrial applications. Notably, extensive research within the scientific community has focused on Aspergillus and Trichoderma species for the industrial production of proteins and enzymes. This review also presents practical examples of genetic engineering strategies aimed at augmenting enzyme secretion in filamentous fungi for various industrial applications. These findings underscore the potential of filamentous fungi as versatile platforms for protein production and highlight avenues for future research and technological advancement in this field. Full article
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12 pages, 4928 KiB  
Article
Genomic and Functional Characterization of CTX-M-15-Producing Klebsiella pneumoniae ST307 Isolated from Imported Leopard Tortoises in Germany
by Tammy J. Schmidt, Sophie Aurich, Franziska Unger, Tobias Eisenberg and Christa Ewers
Appl. Microbiol. 2024, 4(2), 782-793; https://doi.org/10.3390/applmicrobiol4020054 - 11 May 2024
Viewed by 670
Abstract
The Klebsiella pneumoniae ST307 clone, identified in the mid-1990s, has emerged as a global antimicrobial-resistant (AMR) high-risk clone, significantly contributing to the global health challenge also posed by other AMR K. pneumoniae lineages. The acquisition of a blaCTX-M-15-carrying plasmid has facilitated [...] Read more.
The Klebsiella pneumoniae ST307 clone, identified in the mid-1990s, has emerged as a global antimicrobial-resistant (AMR) high-risk clone, significantly contributing to the global health challenge also posed by other AMR K. pneumoniae lineages. The acquisition of a blaCTX-M-15-carrying plasmid has facilitated its widespread dissemination. At Europe’s major transport hub for the movement of live animals, Frankfurt Airport, a shipment of 20 live leopard tortoises was sampled during German border control in 2014. Phylogenetic analysis (MLST) identified a K. pneumoniae ST307 strain, prompting further investigation. Our analysis revealed the presence of a ~193 kb plasmid carrying a broad range of AMR genes, including blaCTX-M-15, blaTEM-1B, blaOXA-1, aac(3)-IIa, aac(6′)-Ib-cr, aph(3″)-Ib, aph(6)-Id, and qnrB1. Additionally, mutations in the quinolone resistance-determining region in gyrA (S83I) and parC (S80I) were detected. Phenotypic testing demonstrated resistance of the isolate to the most common antimicrobials used in both human and veterinary medicine; exceptions included carbapenems and newer β-lactamase inhibitor combinations. Because the role of imported exotic animals in the dissemination of AMR genes is largely deficient, the present study fills yet missing mosaic pieces in the complete picture of extended-spectrum β-lactamase (ESBL)-producing Enterobacterales. Full article
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11 pages, 1309 KiB  
Article
Genes of Salmonella enterica Serovar Enteritidis Involved in Biofilm Formation
by Seulgi Lee and Jinru Chen
Appl. Microbiol. 2024, 4(2), 771-781; https://doi.org/10.3390/applmicrobiol4020053 - 10 May 2024
Viewed by 826
Abstract
Although biofilms contribute to bacterial tolerance to desiccation and survival in low-moisture foods, the molecular mechanisms underlying biofilm formation have not been fully understood. This study created a mutant library from Salmonella Enteritidis using mini-Tn10 transposon mutagenesis. The biofilm-forming potential of acquired [...] Read more.
Although biofilms contribute to bacterial tolerance to desiccation and survival in low-moisture foods, the molecular mechanisms underlying biofilm formation have not been fully understood. This study created a mutant library from Salmonella Enteritidis using mini-Tn10 transposon mutagenesis. The biofilm-forming potential of acquired mutants was assessed before the genomic DNA of the mutants that formed significantly (p ≤ 0.05) less biofilm mass than their wildtype parent strain was extracted for deep DNA sequencing. The gene of each mutant interrupted by mini-Tn10 insertion was identified by aligning obtained sequencing data with the reference Genbank sequences using a BLAST search. Sixty-four mutant colonies were selected, and five mutants that formed the least amount of biofilm mass compared to the wildtype parent strain were selected for sequencing analysis. The results of the BLAST search revealed that the gene interrupted by mini-Tn10 in each mutant is responsible for the biosynthesis of aldehyde dehydrogenase (EutE), cysteine desulfurase (SufS or SufE), a transporter protein, porin OmpL, and a ribbon–helix–helix protein from the CopG family, respectively. Knock-off mutant construction is a possible approach to verify the potential of the identified genes to serve as targets of antimicrobial intervention to control Salmonella colonization on low-moisture foods and in their production environment. Full article
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18 pages, 2216 KiB  
Article
Antimicrobial Activity of Fungal Endophytes Associated with Peperomia argyreia (Piperaceae)
by Melisa Isabel Barolo, María Victoria Castelli and Silvia Noelí López
Appl. Microbiol. 2024, 4(2), 753-770; https://doi.org/10.3390/applmicrobiol4020052 - 5 May 2024
Viewed by 815
Abstract
The endophytic fungal biodiversity of unique plants like Peperomia argyreia (Miq.) É. Morren (Piperaceae) has antimicrobial properties and can be employed for infection treatment. Fungal isolates were obtained from appropriately treated plant tissues cultured in solid media, characterized by morphology, and identified by [...] Read more.
The endophytic fungal biodiversity of unique plants like Peperomia argyreia (Miq.) É. Morren (Piperaceae) has antimicrobial properties and can be employed for infection treatment. Fungal isolates were obtained from appropriately treated plant tissues cultured in solid media, characterized by morphology, and identified by molecular biology using ITS and NL primers. The antimicrobial properties of fungal extracts were analyzed by combining microdilution and bioautographic assays complemented with metabolic profiling by automated thin-layer chromatography and 1H NMR techniques. Thirty-one filamentous fungi were isolated and characterized by ITS and/or D1/D2 region amplification of rDNA, identified as Thermothielavioides, Trichoderma, Cyphellophora, Cladosporium, Arcopilus, Plectosphaerella; Chaetomium, Sporothrix, Alboefibula, and Penicillium. Thermothielavioides spp. inhibited Staphylococcus aureus ATCC 25923; moreover, Penicillium westlingii P4 showed inhibitory activity on Ascochyta rabiei AR2. The bioactivity-guided fractionation of the EtOAc extract (MIC = 62.5 μg/mL) of P. westlingii P4 allowed the purification of citrinin as the main inhibitory compound (MIC = 62.5 μg/mL). Peperomia argyreia harbors a rich and diverse endophytic community able to produce bioactive molecules. Citrinin, with a minor influence of volatile compounds biosynthesized by P. westlingii P4, was responsible for the inhibition of A. rabiei AR2. Full article
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8 pages, 608 KiB  
Article
A Sublethal Concentration of Chlorine Induces Antibiotic Resistance in Salmonella via Production of Reactive Oxygen Species
by Mohammed Aljuwayd, Israa Abdullah Malli, Steven C. Ricke and Young Min Kwon
Appl. Microbiol. 2024, 4(2), 745-752; https://doi.org/10.3390/applmicrobiol4020051 - 30 Apr 2024
Viewed by 608
Abstract
Studies have shown that the production of reactive oxygen species (ROS) is triggered by bactericidal antibiotics, which contributes significantly to the killing of bacterial cells and increasing mutations in surviving cells. In this study, we hypothesized that exposure of Salmonella to sublethal concentrations [...] Read more.
Studies have shown that the production of reactive oxygen species (ROS) is triggered by bactericidal antibiotics, which contributes significantly to the killing of bacterial cells and increasing mutations in surviving cells. In this study, we hypothesized that exposure of Salmonella to sublethal concentrations of hypochlorite (NaOCl), a commonly used sanitizer in household and food industries increases mutation rates, leading to the development of antibiotic resistance. We found that a sublethal concentration (20 ppm) of NaOCl increased the mutation rates of S. typhimurium 14028s significantly (p < 0.05), which was prevented by the ROS scavenger thiourea, supporting that the increased mutation was due to NaOCl-triggered ROS production. We further found that the exposure of S. typhimurium 14028s to the same sublethal concentration of NaOCl increases resistance to kanamycin among the 3 antibiotics evaluated. The results of this study suggest that when NaOCl applied as a sanitizer fails to kill Salmonella due to diluted local concentrations or presence of organic materials, it can cause an adverse outcome of developing antibiotic resistance of the pathogen. Full article
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14 pages, 3566 KiB  
Article
Effects of Vacuum Pasteurization on the Nutritional, Sensory and Microbiological Properties of Orange (Citrus × sinensis) and Carrot (Daucus carota L.) Nectar
by Llerena-Silva Wilma, José Burgos, Jacqueline Ortiz, Iván Samaniego, Jhunior Marcia, Molina José, Christian Vallejo, Ignacio Angós, Ajitesh Yaday and Ricardo Santos Alemán
Appl. Microbiol. 2024, 4(2), 731-744; https://doi.org/10.3390/applmicrobiol4020050 - 28 Apr 2024
Viewed by 881
Abstract
This study involved the evaluation of the effect of vacuum pasteurization on physicochemical characteristics (pH, total soluble solids, titratable acidity, chroma, tone, IO, vitamin C, 5-hydroxymethylfurfural), microbiological properties (Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, total coliforms, total mesophilic aerobes, [...] Read more.
This study involved the evaluation of the effect of vacuum pasteurization on physicochemical characteristics (pH, total soluble solids, titratable acidity, chroma, tone, IO, vitamin C, 5-hydroxymethylfurfural), microbiological properties (Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, total coliforms, total mesophilic aerobes, molds and yeasts) and sensory characteristics of orange and carrot nectar. The thermal treatments were designed based on the thermal lethality of two heat-resistant microorganisms typical of the product (Neosartorya fischeri and Zygosaccaromyces bailii). The evaluation was carried out on raw nectar and pasteurized nectar. The shelf life was estimated to be 30 days (6 °C). The most favorable results were obtained by applying a heat treatment at 88 °C for 32.68 min, managing to retain 85.87% of vitamin C and a microbiological stability of 12 days (6 ± 0.6 °C) with regard to total mesophilic aerobes. Likewise, the tasters established that this treatment resulted in the best flavor, texture and acceptability characteristics. Full article
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11 pages, 609 KiB  
Article
The Dose Response Effects of Partially Hydrolyzed Guar Gum on Gut Microbiome of Healthy Adults
by Megan Edelman, Qi Wang, Rylee Ahnen and Joanne Slavin
Appl. Microbiol. 2024, 4(2), 720-730; https://doi.org/10.3390/applmicrobiol4020049 - 27 Apr 2024
Viewed by 1567
Abstract
Partially hydrolyzed guar gum (PHGG) is a water-soluble, prebiotic fiber that is used in foods and supplements. The effects of PHGG and its role in gut health are still being studied. The purpose of this study was to evaluate changes in the gut [...] Read more.
Partially hydrolyzed guar gum (PHGG) is a water-soluble, prebiotic fiber that is used in foods and supplements. The effects of PHGG and its role in gut health are still being studied. The purpose of this study was to evaluate changes in the gut microbiome composition of healthy individuals in response to low-dose PHGG supplementation compared with a low fiber diet. A randomized, double-blind, placebo-controlled crossover study was performed on 33 healthy subjects (17 males, 16 females). Each subject completed three 14-day treatment periods with a 2-week washout between each period. Treatments included supplementation with 3 g PHGG, 6 g PHGG, or a placebo. During all periods, the participants followed a low fiber diet (≤14 g/day). Stools were collected on days 0 and 14 of each period. Gut microbiome profiling was performed using 16S rRNA sequencing. Stools were assessed by investigators with the Bristol Stool Form Scale as a secondary outcome. Saliva cortisol was also measured as a secondary outcome. Supplementation of 3 g and 6 g PHGG significantly increased Verrucomicrobia on day 14 when compared to the placebo (p = 0.0066 and p = 0.0068, respectively). On the genus level, Akkermansia was significantly increased on day 14 with both the 3 g and 6 g PHGG doses (p = 0.0081 and p = 0.0083). Faecalibacterium was significantly decreased on day 14 with 3 g PHGG (p = 0.0054). Supplementing with low doses of PHGG has the potential to cause shifts in the gut microbiome composition. By increasing beneficial microbes, PHGG can improve the microbiome composition of healthy individuals and may play a role in the treatment of inflammatory gastrointestinal diseases. Full article
(This article belongs to the Special Issue Human Microbiota Influence on Human Health Status 2.0)
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16 pages, 2403 KiB  
Article
Impact of Carao (Cassia grandis) on Lactobacillus plantarum Immunomodulatory and Probiotic Capacity
by Jhunior Marcia, Hector Manuel Zumbado, Manuel Álvarez Gil, Daniel Martín-Vertedor, Ismael Montero-Fernández, Ajitesh Yadav and Ricardo S. Aleman
Appl. Microbiol. 2024, 4(2), 704-719; https://doi.org/10.3390/applmicrobiol4020048 - 22 Apr 2024
Viewed by 989
Abstract
Lactobacillus plantarum has beneficial effects on the reduction of symptoms of poor lactose digestion and hypercholesterolemia, removal of the duration and severity of diarrheal processes, improvement of the intestinal permeability barrier, prevention of some types of cancer by adsorption or inactivation of genotoxic [...] Read more.
Lactobacillus plantarum has beneficial effects on the reduction of symptoms of poor lactose digestion and hypercholesterolemia, removal of the duration and severity of diarrheal processes, improvement of the intestinal permeability barrier, prevention of some types of cancer by adsorption or inactivation of genotoxic agents, increased resistance to intestinal and extraintestinal infections, attenuation of inflammatory bowel disease, and prevention of allergies (especially food). On the other hand, carao (Cassia grandis) has shown remarkable nutritious content with influential dietary applications. As a result, this investigation aimed to explore the effect of Cassia grandis pulp on viability of Lactobacillus plantarum under gastrointestinal conditions, immunomodulatory capacity, and probiotic potential. Adding carao to the medium under different experimental conditions, including rich and minimal culture media and a gastrointestinal digestion process of skimmed milk, did not substantially affect Lactobacillus plantarum’s growth but prolonged its viability. The administration of Lactobacillus plantarum with carao in mice did not induce a proinflammatory response at a systemic level. Still, it did cause an increase in the production of immunoregulatory cytokines. Also, the viability of TSB broth was improved by adding carao. Carao improved the growth of acid tolerance, bile tolerance, growth in TSB broth, and NaCl resistance. According to the results, carao may enhance the characteristics of L. plantarum when enriching fermented dairy products. Full article
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22 pages, 4109 KiB  
Article
Diversity of Microbial Communities in Trade Wastes—Implications for Treatments and Operations
by Jake A. K. Elliott, Christian Krohn and Andrew S. Ball
Appl. Microbiol. 2024, 4(2), 682-703; https://doi.org/10.3390/applmicrobiol4020047 - 19 Apr 2024
Viewed by 1134
Abstract
Industrial wastewaters display a complex and diverse range of physicochemical properties that are measured, studied, and treated by businesses and water service providers. Less frequently measured are the microbial communities in these wastes, despite possible implications for health, equipment maintenance, and the environment. [...] Read more.
Industrial wastewaters display a complex and diverse range of physicochemical properties that are measured, studied, and treated by businesses and water service providers. Less frequently measured are the microbial communities in these wastes, despite possible implications for health, equipment maintenance, and the environment. This study aimed to assess the microbial communities of eighteen raw and discharge-ready wastewaters across eleven industrial sites to compare the microbial compositions of these wastewaters across different industry sectors, on-site treatment levels, and other wastewater components. The potential for variance in the biomethane yield, depending on microbial communities, was also measured. Using targeted sequencing, a unique taxonomy was identified, including genera linked to animals (Acetitomaculum, Lactobacillus, NK4A214, Prevotella, and Shuttleworthia), cooling water (Bosea, Legionella, Methyloversatilis, and Reyranella), and extreme conditions (Alkalibacillus, Geobacillus, Halorubrum, and Pyrobaculum). However, the compositions of the microbial communities were not found to be directly correlated to industry sector or on-site treatment levels, nor were they found to have a direct effect on the biomethane potential. However, the presence of certain individual taxa is linked to the methane yield and treatment status and may be explained in the context of physicochemical properties while serving as potential markers for identifying, improving, or developing on-site processes. Full article
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17 pages, 2631 KiB  
Article
Bioprospection of Bacterial Strains from Chromite Process Industry Residues from Mexico for Potential Remediation
by Paola Abigail Martínez-Aldape, Mario Enrique Sandoval-Vergara, Reyna Edith Padilla-Hernández, César Augusto Caretta, Julio César Valerdi-Negreros, Pablo Casanova, Magna Maria Monteiro, Claire Gassie, Marisol Goñi-Urriza, Elcia Margareth Souza Brito and Remy Guyoneaud
Appl. Microbiol. 2024, 4(2), 665-681; https://doi.org/10.3390/applmicrobiol4020046 - 18 Apr 2024
Viewed by 912
Abstract
Industrial residues with high concentrations of hexavalent chromium [Cr(VI)], characterized by an alkaline pH (between 9 and 13) and high salinity (around 100 psu), were used as a source for extremophilic chromium-resistant and -reducing microorganisms. An investigation of biodiversity through MiSeq showed the [...] Read more.
Industrial residues with high concentrations of hexavalent chromium [Cr(VI)], characterized by an alkaline pH (between 9 and 13) and high salinity (around 100 psu), were used as a source for extremophilic chromium-resistant and -reducing microorganisms. An investigation of biodiversity through MiSeq showed the presence of 20 bacterial classes, with Bacilli (47%), Negativicutes (15%), Bacteriodia (8%), Gammaproteobacteria (7%) and Clostridia (5%) being the most abundant. The bioprospection allowed the cultivation of 87 heterotrophic bacterial colonies and 17 bacterial isolates at the end of the isolation, and screening procedures were obtained. The isolates were related to Cellulosimicrobium aquatile, C. funkei, Acinetobacter radioresistens, Staphylococcus equorum, S. epidermis, Brachybacterium paraconglometratum, Glutamicibacter creatinolyticus, Pseudomonas songnenensis, Microbacterium algeriense and Pantoea eucalypti, most of them being resistant to Cr(VI). Resistances of up to 400 mg.L1 of chromate were obtained for four related strains (QReMLB55A, QRePRA55, QReMLB33A and QReMLB44C). The C. aquatile strain QReMLB55A and the P. songnenensis strain QReMLB33A were exposed to K2Cr2O7 (200 mg.L1) under optimal conditions, diminishing 94% and 24% of the Cr(VI) in 6 days, respectively. These strains exhibited a high potential for chromium remediation biotechnologies. Full article
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15 pages, 1066 KiB  
Article
Molecular Characterization of the Gorgonzola Cheese Mycobiota and Selection of a Putative Probiotic Saccharomyces cerevisiae var. boulardii for Evaluation as a Veterinary Feed Additive
by Samuele Voyron, Francesca Bietto, Mauro Fontana, Elisa Martello, Natascia Bruni and Enrica Pessione
Appl. Microbiol. 2024, 4(2), 650-664; https://doi.org/10.3390/applmicrobiol4020045 - 3 Apr 2024
Viewed by 828
Abstract
Gorgonzola is an Italian “erborinato” blue cheese from cow’s milk, bearing blue-green “parsley-like” spots due to the spread of Penicillium roqueforti mycelium. Due to its pH, water activity, and high nutrient content, as well as the environmental conditions required for its maturation, Gorgonzola [...] Read more.
Gorgonzola is an Italian “erborinato” blue cheese from cow’s milk, bearing blue-green “parsley-like” spots due to the spread of Penicillium roqueforti mycelium. Due to its pH, water activity, and high nutrient content, as well as the environmental conditions required for its maturation, Gorgonzola constitutes an optimal ecological niche supporting the growth of both yeasts and filamentous fungi. Therefore, exploring the abundant mycobiota present in this peculiar habitat is of great interest regarding the search for new probiotic strains. The present investigation aimed to characterize the Gorgonzola mycobiota using both phenotypic (macroscopic and microscopic morphological analyses) and genotypic (DNA barcoding) analyses to find possible putative probiotic strains to be used in veterinary medicine in feed supplements. Among the different isolated filamentous fungi (Mucor and Penicillium) and yeasts (Yarrowia, Debaryomyces, Saccharomyces, and Sporobolomyces), we selected a strain of Saccharomyces cerevisiae var. boulardii. We tested its adaptation to thermal stress and its stability in feed matrices. The overall results highlight that the selected strain is stable for three months and can be considered as a possible candidate for use as a probiotic in veterinary feed supplements. Full article
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15 pages, 2891 KiB  
Article
Longitudinal Sequencing and Variant Detection of SARS-CoV-2 across Southern California Wastewater
by Jason A. Rothman, Andrew Saghir, Amity G. Zimmer-Faust, Kylie Langlois, Kayla Raygoza, Joshua A. Steele, John F. Griffith and Katrine L. Whiteson
Appl. Microbiol. 2024, 4(2), 635-649; https://doi.org/10.3390/applmicrobiol4020044 - 29 Mar 2024
Viewed by 771
Abstract
Wastewater-based epidemiology (WBE) is useful for detecting pathogen prevalence and may serve to effectively monitor diseases across broad scales. WBE has been used throughout the COVID-19 pandemic to track disease burden through quantifying SARS-CoV-2 RNA present in wastewater. Aside from case load estimation, [...] Read more.
Wastewater-based epidemiology (WBE) is useful for detecting pathogen prevalence and may serve to effectively monitor diseases across broad scales. WBE has been used throughout the COVID-19 pandemic to track disease burden through quantifying SARS-CoV-2 RNA present in wastewater. Aside from case load estimation, WBE is being used to assay viral genomic diversity and emerging potential SARS-CoV-2 variants. Here, we present a study in which we sequenced RNA extracted from sewage influent obtained from eight wastewater treatment plants representing 16 million people in Southern California from April 2020 to August 2021. We sequenced SARS-CoV-2 with two methods: Illumina Respiratory Virus-Enriched metatranscriptomic sequencing (N = 269), and QIAseq SARS-CoV-2-tiled amplicon sequencing (N = 95). We classified SARS-CoV-2 reads into lineages and sublineages that approximated named variants and identified single nucleotide variants (SNVs), of which many are putatively novel SNVs and SNVs of unknown potential function and prevalence. Through our retrospective study, we also show that several SARS-CoV-2 sublineages were detected in wastewater before clinical detection, which may assist in the prediction of future variants of concern. Lastly, we show that sublineage diversity was similar across Southern California and that diversity changed over time, indicating that WBE is effective across megaregions. As the COVID-19 pandemic moves to new phases, and SARS-CoV-2 variants emerge, monitoring wastewater is important to understand local- and population-level dynamics of the virus. These results will aid in our ability to monitor the evolutionary potential of SARS-CoV-2 and help understand circulating SNVs to further combat COVID-19. Full article
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15 pages, 3262 KiB  
Article
Porphyromonas gingivalis Strain W83 Infection Induces Liver Injury in Experimental Alcohol-Associated Liver Disease (ALD) in Mice
by Yun Zhou, Craig McClain and Wenke Feng
Appl. Microbiol. 2024, 4(2), 620-634; https://doi.org/10.3390/applmicrobiol4020043 - 27 Mar 2024
Viewed by 880
Abstract
The liver plays a vital role in the defense against infections. Porphyromonas gingivalis (P. gingivalis), a dominant etiologic oral bacterium implicated in periodontal disease (PD), has been associated with various systemic diseases. This study aimed to investigate the influence of P. [...] Read more.
The liver plays a vital role in the defense against infections. Porphyromonas gingivalis (P. gingivalis), a dominant etiologic oral bacterium implicated in periodontal disease (PD), has been associated with various systemic diseases. This study aimed to investigate the influence of P. gingivalis on alcohol-associated liver diseases (ALD). Mice were fed a Lieber–DeCarli liquid diet containing 5% ethanol for 10 days after an initial adaptation period on a diet with lower ethanol content for 7 days. Two days before tissue sample collection, the mice were administered P. gingivalis strain W83 (Pg) through intraperitoneal injection (IP). Pair-fed mice with Pg infection (PF+Pg) exhibited an activated immune response to combat infections. However, alcohol-fed mice with Pg infection (AF+Pg) showed liver injury with noticeable abscess lesions and elevated serum alanine aminotransferase (ALT) levels. Additionally, these mice displayed liver infiltration of inflammatory monocytes and significant downregulation of proinflammatory cytokine gene expression levels; and AF+Pg mice also demonstrated increased intrahepatic neutrophil infiltration, as confirmed by chloroacetate esterase (CAE) staining, along with elevated gene expression levels of neutrophil cytosol factor 1 (Ncf1), neutrophilic inflammation driver lipocalin 2 (Lcn2), and complement component C5a receptor 1 (C5ar1), which are associated with neutrophilic inflammation. Interestingly, compared to PF+Pg mice, the livers of AF+Pg mice exhibited downregulation of gene expression levels of NADPH oxidase 2 (Cybb), the leukocyte adhesion molecule Cd18, and the Toll-like receptor adaptor Myd88. Consequently, impaired clearance of P. gingivalis and other bacteria in the liver, increased susceptibility to infections, and inflammation-associated hepatic necrotic cell death were observed in AF+Pg mice, which is likely to have facilitated immune cell infiltration and contributed to liver injury. Furthermore, in addition to the Srebf1/Fasn pathway induced by alcohol feeding, Pg infection also activated carbohydrate response element-binding protein (ChREBP) in AF+Pg mice. In summary, this study demonstrates that P. gingivalis infection, acting as a “second hit”, induces dysfunction of immune response and impairs the clearance of bacteria and infections in alcohol-sensitized livers. This process drives the development of liver injury. Full article
(This article belongs to the Special Issue Human Microbiota Influence on Human Health Status 2.0)
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13 pages, 291 KiB  
Article
In Silico Prophage Analysis of Halobacterium salinarum ATCC 33170
by Danielle L. Peters, Bassel Akache, Wangxue Chen and Michael J. McCluskie
Appl. Microbiol. 2024, 4(2), 607-619; https://doi.org/10.3390/applmicrobiol4020042 - 26 Mar 2024
Viewed by 624
Abstract
The extremophile Halobacterium salinarum is an aerobic archaeon that has adapted to thrive in high-salt environments such as salted fish, hypersaline lakes, and salterns. Halophiles have garnered significant interest due to their unique interactions with bacteriophages known as haloarchaeophages. Studies have identified and [...] Read more.
The extremophile Halobacterium salinarum is an aerobic archaeon that has adapted to thrive in high-salt environments such as salted fish, hypersaline lakes, and salterns. Halophiles have garnered significant interest due to their unique interactions with bacteriophages known as haloarchaeophages. Studies have identified and characterized prophages in halophilic archaea, such as Haloferax volcanii, Haloquadratum walsbyi, and Haloarcula marismortui. Still, an investigation has yet to be conducted into the presence of prophage elements on Halobacterium salinarum ATCC 33170. This is of particular interest to us as we are using this strain as a source of archaeol, as one of the components of our sulfated lactosyl archaeol (SLA) archaeosome adjuvant. Genomic contigs of strain 33170 were bioinformatically assessed for prophage-like features using BLAST, PHASTER, InterProScan, and PHYRE2. A 7 kb region encoding six genes was identified as an incomplete prophage, and the proteins were further analyzed, revealing high homology to proteins encoded by bacteria, archaea, and an IS200 transposon. Restricting the BLASTp database to viruses resulted in hits to both myo- and siphoviral proteins, which would be unusual for an intact prophage. Additionally, no known phage structural proteins were identified in the search, suggesting a low chance that H. salinarum ATCC 33170 harbors a latent prophage. Full article
13 pages, 619 KiB  
Review
The Influence of Technological Shifts in the Food Chain on the Emergence of Foodborne Pathogens: An Overview
by Saja Hamaideh, Amin N. Olaimat, Murad A. Al-Holy, Ahmad Ababneh, Hafiz Muhammad Shahbaz, Mahmoud Abughoush, Anas Al-Nabulsi, Tareq Osaili, Mutamed Ayyash and Richard A. Holley
Appl. Microbiol. 2024, 4(2), 594-606; https://doi.org/10.3390/applmicrobiol4020041 - 25 Mar 2024
Viewed by 1142
Abstract
The transformation of the food chain due to technological advances has had significant implications in regard to food safety. A noteworthy trend in this evolution relates to the emergence of new or previously unseen pathogens within products, thereby altering the landscape of foodborne [...] Read more.
The transformation of the food chain due to technological advances has had significant implications in regard to food safety. A noteworthy trend in this evolution relates to the emergence of new or previously unseen pathogens within products, thereby altering the landscape of foodborne illness epidemiology. The escalating frequency of these events underscores the need for a comprehensive re-evaluation of preventive strategies. The occurrence of novel species of bacteria, viruses, parasites, and unusual biotoxins from unexpected sources has challenged the previous limits that had been set to prevent foodborne illness outbreaks. The repercussions, ranging from detrimental effects on public health to economic burden, are influenced by a myriad of factors affecting the evolution of foodborne pathogens and emerging ailments. Among these factors are shifts in population demographics and behaviors, especially dietary patterns, as well as climate extremes, advances in more precise pathogen detection, microbial adaptation, evolving agricultural practices, and transformative changes within the food industry. This review critically examines the impact of technological metamorphosis along the food chain, encompassing production, processing, handling, packaging, storage, transportation, and industry demographics on the dynamics influencing the emergence of foodborne pathogens. Additionally, potential solutions to mitigate and manage this escalating issue are proposed. Full article
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12 pages, 1208 KiB  
Article
Breaking the Mold: Towards Rapid and Cost-Effective Microbial Contamination Detection in Paints and Cosmetics Using ATP-Bioluminescence
by Mira Mutschlechner, Daniela Chisté and Harald Schöbel
Appl. Microbiol. 2024, 4(2), 582-593; https://doi.org/10.3390/applmicrobiol4020040 - 22 Mar 2024
Viewed by 836
Abstract
Traditional culture-based methods, though a “gold standard” for bacterial detection in various industrial sectors, do often not fulfill today’s high requirements regarding rapidity, on-site applicability, and cost-efficiency both during operation and evaluation. Here, the feasibility of using an adenosine triphosphate (ATP)-based assay for [...] Read more.
Traditional culture-based methods, though a “gold standard” for bacterial detection in various industrial sectors, do often not fulfill today’s high requirements regarding rapidity, on-site applicability, and cost-efficiency both during operation and evaluation. Here, the feasibility of using an adenosine triphosphate (ATP)-based assay for determining microbial contaminations in paints and cosmetics was investigated and compared with standard plate count techniques and dipslides. Therefore, we initially determined the level of sensitivity and assessed the accuracy and concordance among the different methods via spiking tests using a mix of frequently abundant bacterial species to simulate microbial contamination. Bioluminescence intensity was linearly proportional to log colony counts over five orders of magnitude (R2 = 0.99), indicating a high level of sensitivity. Overall, the accuracy varied depending on the test specimen, most probably due to matrix-related quenching effects. Although the degree of conformity was consistently higher at target concentrations ≥ 105 CFU·mL−1, microbial contaminations were detectable down to 103 CFU·mL−1, thus meeting the high requirements of various industries. ATP-based results tended to be within an order of magnitude lower than the reference. However, bearing that in mind, the developed assay serves as a rapid, real-time alternative for routine quality control and hygiene monitoring. Full article
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19 pages, 2624 KiB  
Article
Green Macroalgae Hydrolysate for Biofuel Production: Potential of Ulva rigida
by Walaa Sayed, Audrey Cabrol, Alaa Salma, Abdeltif Amrane, Maud Benoit, Ronan Pierre and Hayet Djelal
Appl. Microbiol. 2024, 4(2), 563-581; https://doi.org/10.3390/applmicrobiol4020039 - 22 Mar 2024
Viewed by 819
Abstract
In this study, the green macroalgae Ulva rigida, which contains 34.9% carbohydrates, underwent treatment with commercial hydrolytic enzymes. This treatment yielded a hydrolysate that contained 23 ± 0.6 g·L−1 of glucose, which was subsequently fermented with Saccharomyces cerevisiae. The fermentation process [...] Read more.
In this study, the green macroalgae Ulva rigida, which contains 34.9% carbohydrates, underwent treatment with commercial hydrolytic enzymes. This treatment yielded a hydrolysate that contained 23 ± 0.6 g·L−1 of glucose, which was subsequently fermented with Saccharomyces cerevisiae. The fermentation process resulted in an ethanol concentration of 9.55 ± 0.20 g·L−1. The optimal conditions for ethanol production by S. cerevisiae were identified as follows: non-sterilized conditions, an absence of enrichment, and using an inoculum size of 118 mg·L−1. Under these conditions, the fermentation of the green macroalgal hydrolysate achieved a remarkable conversion efficiency of 80.78%. The ethanol o/t ratio, namely the ratios of the experimental to theoretical ethanol produced, for Scheffersomyces stipitis, Candida guilliermondii, Kluyveromyces marxianus, and S. cerevisiae after 48 h of fermentation were 52.25, 63.20, 70.49, and 82.87%, respectively. Furthermore, S. cerevisiae exhibited the best outcomes in terms of ethanol production (9.35 g·L−1) and conversion efficiency (80.78%) after 24 h (optimal time) of fermentation. Full article
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