Search Results (6,918)

Background/Objectives: Antimicrobial resistance (AMR) contributes to millions of deaths globally each year, creating an urgent need for new therapeutic agents. Antimicrobial peptides (AMPs) have emerged as promising candidates due to their potential to combat AMR pathogens. This study aimed to evaluate the antimicrobial activity of an AMP from a soil-derived bacterial isolate against Gram-negative bacteria. Method: Soil bacteria were isolated and screened for antimicrobial activity. The bioactive peptide was purified and determined its structure and antimicrobial efficacy. Genomic analysis was conducted to predict the biosynthetic gene clusters (BGCs) responsible for AMP production. Results: Genomic analysis identified the isolate as Paenibacillus sp. Na14, which exhibited low genomic similarity (61.0%) to other known Paenibacillus species, suggesting it may represent a novel species. The AMP from the Na14 strain exhibited heat stability up to 90 °C for 3 h and retained its activity across a broad pH range from 3 to 11. Structural analysis revealed that the Na14 peptide consisted of 14 amino acid residues, adopting an α-helical structure. This peptide exhibited bactericidal activity at concentrations of 2–4 µg/mL within 6–12 h, and its killing rate was concentration-dependent. The peptide was found to disrupt the bacterial membranes. The Na14 peptide shared 64.29% sequence similarity with brevibacillin 2V, an AMP from Brevibacillus sp., which also belongs to the Paenibacillaceae family. Genomic annotation identified BGCs associated with secondary metabolism, with a particular focus on non-ribosomal peptide synthetase (NRPS) gene clusters. Structural modeling of the predicted NRPS enzymes showed high similarity to known NRPS modules in Brevibacillus species. These genomic findings provide evidence supporting the similarity between the Na14 peptide and brevibacillin 2V. Conclusions: This study highlights the discovery of a novel AMP with potent activity against Gram-negative pathogens and provides new insight into conserved AMP biosynthetic enzymes within the Paenibacillaceae family. Full article

Biofilms are a spontaneously formed slimy matrix of extracellular polymeric substances (EPS) enveloping miniature bacterial colonies, which aid in pathogen colonization, shielding the bacteria from antibiotics, as well as imparting them resistance towards the same. Biofilms employ a robust communication mechanism called quorum sensing that serves to keep their population density constant. What is most significant about biofilms is that they contribute to the development of bacterial virulence by providing protection to pathogenic species, allowing them to colonize the host, and also inhibiting the activities of antimicrobials on them. They grow on animate surfaces (such as on teeth and intestinal mucosa, etc.) and inanimate objects (like catheters, contact lenses, pacemakers, endotracheal devices, intrauterine devices, and stents, etc.) alike. It has been reported that as much as 80% of human infections involve biofilms. Serious implications of biofilms include the necessity of greater concentrations of antibiotics to treat common human infections, even contributing to antimicrobial resistance (AMR), since bacteria embedded within biofilms are protected from the action of potential antibiotics. This review explores various contemporary strategies for controlling biofilms, focusing on their modes of action, mechanisms of drug resistance, and innovative approaches to find a solution in this regard. This review interestingly targets the extracellular polymeric matrix as a highly effective strategy to counteract the potential harm of biofilms since it plays a critical role in biofilm formation and significantly contributes to antimicrobial resistance. Full article

Background/Objectives: The rapid emergence of multidrug-resistant bacterial infections demands innovative non-antibiotic therapeutic strategies. Dual-modal photoresponse therapy integrating photodynamic (PDT) and photothermal (PTT) effects offers a promising rapid antibacterial approach, yet designing single-material systems with synergistic enhancement remains challenging. This study aims to develop uniform Cu-based metal–organic framework micrometer cubes (Cu-BN) for efficient PDT/PTT synergy. Methods: Cu-BN cubes were synthesized via a one-step hydrothermal method using Cu(NO₃)₂ and 2-amino-p-benzoic acid. The material’s dual-mode responsiveness to visible light (420 nm) and near-infrared light (808 nm) was characterized through UV–Vis spectroscopy, photothermal profiling, and reactive oxygen species (ROS) generation assays. Antibacterial efficacy against multidrug-resistant Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was quantified via colony counting under dual-light irradiation. Results: Under synergistic 420 + 808 nm irradiation for 15 min, Cu-BN (200 μg/mL) achieved rapid eradication of multidrug-resistant E. coli (99.94%) and S. aureus (99.83%). The material reached 58.6 °C under dual-light exposure, significantly exceeding single-light performance. Photodynamic analysis confirmed a 78.7% singlet oxygen (¹O₂) conversion rate. This enhancement stems from PTT-induced membrane permeabilization accelerating ROS diffusion, while PDT-generated ROS sensitized bacteria to thermal damage. Conclusions: This integrated design enables spatiotemporal PDT/PTT synergy within a single Cu-BN system, establishing a new paradigm for rapid-acting, broad-spectrum non-antibiotic antimicrobials. The work provides critical insights for developing light-responsive biomaterials against drug-resistant infections. Full article

Foodborne illness caused by bacterial pathogens is a global health concern and results in millions of infections annually. Therefore, food products typically undergo several processing stages, including sanitation steps, before being distributed in an attempt to remove pathogens. However, many sanitation methods have compounding effects on the color, texture, flavor, and nutritional quality of the product or do not effectively reduce the pathogens that food can be exposed to. Some bacterial pathogens particularly possess traits and tactics that make them even more difficult to mitigate such as biofilm formation. Non-thermal plasma sanitation techniques, including plasma-treated water (PTW), have proven to be promising methods that significantly reduce pathogenic bacteria that food is exposed to. Published work reveals that PTW can effectively mitigate both gram-positive and gram-negative bacterial biofilms. This study presents a novel analysis of the differences in antimicrobial effects of PTW treatment between biofilm-forming gram-positive bacteria, commonly associated with foodborne illness, that are sporulating (Bacillus cereus) and non-sporulating (Listeria monocytogenes). After treatment with PTW, the results suggest the following hypotheses: (1) that the non-sporulating species experiences less membrane damage but a greater reduction in metabolic activity, leading to a possible viable but non-culturable (VBNC) state, and (2) that the sporulating species undergoes spore formation, which may subsequently convert into vegetative cells over time. PTW treatment on gram-positive bacterial biofilms that persist in food processing environments proves to be effective in reducing the proliferating abilities of the bacteria. However, the variance in PTW’s effects on metabolic activity and cell vitality between sporulating and non-sporulating species suggest that other survival tactics might be induced. This analysis further informs the application of PTW in food processing as an effective sanitation method. Full article

Salinization hinders the restoration of vegetation in salt-affected soils by negatively impacting plant growth and development. Halophytes play a key role in the restoration of saline and degraded lands due to unique features explaining their growth aptitude in such extreme ecosystems. Suaeda fruticosa is an euhalophyte well known for its medicinal properties and its potential for saline soil phytoremediation. However, excessive salt accumulation in soil limits the development of this species. Research findings increasingly advocate the use of extremophile rhizosphere bacteria as an effective approach to reclaim salinized soils, in conjunction with their salt-alleviating effect on plants. Here, a pot experiment was conducted to assess the role of a halotolerant plant growth-promoting actinobacterium, Glutamicibacter sp., on the growth, nutritional status, and shoot content of proline, total soluble carbohydrates, and phenolic compounds in the halophyte S. fruticosa grown for 60 d under high salinity (600 mM NaCl). Results showed that inoculation with Glutamicibacter sp. significantly promoted the growth of inoculated plants under stress conditions. More specifically, bacterial inoculation increased the shoot concentration of proline, total polyphenols, potassium (K⁺), nitrogen (N), and K⁺/Na⁺ ratio in shoots, while significantly decreasing Na⁺ concentrations. These mechanisms partly explain S. fruticosa tolerance to high saline concentrations. Our findings provide some mechanistic elements at the ecophysiological level, enabling a better understanding of the crucial role of plant growth-promoting rhizobacteria (PGPRs) in enhancing halophyte growth and highlight their potential for utilization in restoring vegetation in salt-affected soils. Full article

Background: The COVID-19 pandemic has profoundly altered the clinical and microbiological landscape of respiratory tract infections (RTIs), potentially reshaping pathogen distribution and antimicrobial resistance (AMR) profiles across care settings. Objectives: The objective of this study was to assess temporal trends in respiratory bacterial pathogens, antimicrobial resistance, and polymicrobial infections across three pandemic phases—pre-COVID (2018–2019), COVID (2020–2022), and post-COVID (2022–2024)—in hospitalized and ambulatory patients. Methods: We retrospectively analyzed 1827 respiratory bacterial isolates (hospitalized patients, n = 1032; ambulatory patients, n = 795) collected at a tertiary care center in Northern Italy. Data were stratified by care setting, anatomical site, and pandemic phase. Species identification and susceptibility testing followed EUCAST guidelines. Statistical analysis included chi-square and Fisher’s exact tests. Results: In hospitalized patients, a significant increase in Pseudomonas aeruginosa (from 45.5% pre-COVID to 58.6% post-COVID, p < 0.0001) and Acinetobacter baumannii (from 1.2% to 11.1% during COVID, p < 0.0001) was observed, with 100% extensively drug-resistant (XDR) rates for A. baumannii during the pandemic. Conversely, Staphylococcus aureus significantly declined from 23.6% pre-COVID to 13.7% post-COVID (p = 0.0012). In ambulatory patients, polymicrobial infections peaked at 41.2% during COVID, frequently involving co-isolation of Candida spp. Notably, resistance to benzylpenicillin in Streptococcus pneumoniae reached 80% (4/5 isolates) in hospitalized patients during COVID, and carbapenem-resistant P. aeruginosa (CRPA) significantly increased post-pandemic in ambulatory patients (0% pre-COVID vs. 23.5% post-COVID, p = 0.0014). Conclusions: The pandemic markedly shifted respiratory pathogen dynamics and resistance profiles, with distinct trends observed in hospital and community settings. Persistent resistance phenotypes and frequent polymicrobial infections, particularly involving Candida spp. in outpatients, underscore the need for targeted surveillance and antimicrobial stewardship strategies. Full article

The emergence and spread of antimicrobial resistance among pathogens are significantly reducing available therapeutic options, highlighting the urgent need for novel and complementary treatment strategies. Antimicrobial photodynamic therapy (aPDT) is a promising alternative approach that can overcome antimicrobial resistance through a multitarget mechanism of action, exerting direct bactericidal and fungicidal effects with minimal risk of resistance development. Although aPDT has shown efficacy against a variety of pathogens, data on its activity against large collections of clinical multidrug-resistant strains are still limited. In this study, we assessed the antimicrobial activity of the photosensitizer RLP068/Cl combined with a red light-emitting LED source at 630 nm (Molteni Farmaceutici, Italy) against a large panel of Gram-negative and Gram-positive bacterial strains harboring relevant resistance traits and Candida species. Our results demonstrated the significant microbicidal activity of RLP068/Cl against all of the tested strains regardless of their resistance phenotype, with particularly prominent activity against Gram-positive bacteria (range of bactericidal concentrations 0.05–0.1 µM), which required significantly lower exposure to photosensitizer compared to Candida and Gram-negative species (range 5–20 µM). Overall, these findings support the potential use of RLP068/Cl-mediated aPDT as an effective therapeutic strategy for the management of localized infections caused by MDR organisms, particularly when conventional therapeutic options are limited. Full article

Background/Objectives: Actinobacteria are one of the largest bacterial phyla. These microbes produce bioactive compounds, such as antifungals, antibiotics, immunological modulators, and anti-tumor agents. Studies on actinobacteria isolated from the Brazilian Savannah biome (Cerrado) are scarce and mostly address metagenomics or the search for hydrolytic enzyme-producing microbes. Solanum lycocarpum (lobeira) is a tree widely employed in regional gastronomy and pharmacopeia in Central Brazil. Methods: In this work, 60 actinobacteria isolates were purified from the rhizosphere of S. lycocarpum. Eight Streptomyces spp. isolates were selected for in vitro antifungal activity against Cryptococcus neoformans H99, the C. neoformans 89-610 fluconazole-tolerant strain, C. gattii NIH198, Candida albicans, C. glabrata, and C. parapsilosis. The ability of the aqueous extracts of the isolates to induce the in vitro secretion of tumor necrosis factor (TNF-α), nitric oxide (NO), interleukin-6 (IL-6), and IL-10 by murine macrophages was also evaluated. Results: All extracts showed antifungal activity against at least two yeast species. Streptomyces spp. LAP11, LDB2, and LDB17 inhibited C. neoformans growth by 40–93%. Most extracts (except LAP2) also inhibited C. gattii. None inhibited C. albicans, but all inhibited C. glabrata (40–90%). Streptomyces sp. LAP8 extract increased nitric oxide production by approximately 347-fold in murine macrophages, while LDB11 extract suppressed LPS-induced TNF-α production by 70% and simultaneously increased IL-10 secretion, suggesting immunosuppressive potential. Conclusions: The results revealed that Cerrado actinobacteria-derived aqueous extracts are potential sources of antifungal and immunomodulatory biocompounds. Full article

Autism Spectrum Disorder (ASD) is frequently accompanied by gastrointestinal disturbances, dietary selectivity, and altered stress responses, with growing evidence pointing to gut–brain axis involvement. While intestinal microbiota has been extensively studied, the role of the oral microbiota remains underexplored. This study investigates the associations between oral microbiota composition and behavioral, gastrointestinal, dietary, and neuroendocrine parameters in children with ASD. A total of 45 children aged 2–18 years comprised the study group. Data collection included oral swabs for 16S rRNA gene sequencing, salivary cortisol sampling, dietary records, and standardized behavioral assessments using the Vineland Adaptive Behavior Scale. A total of 363 microbial species across 11 phyla were identified. Significant correlations were observed between specific bacterial taxa and functional gastrointestinal disorders (FGIDs), dietary patterns, salivary cortisol rhythms, and functioning. Children with FGIDs, food selectivity, or macronutrient imbalances exhibited enriched pro-inflammatory taxa (e.g., Selenomonas, Megasphaera), whereas those with typical cortisol secretion or higher adaptive functioning showed greater microbial diversity and abundance of health-associated genera (e.g., Bifidobacterium dentium). These findings suggest that oral microbiota profiles may reflect systemic physiological and neurobehavioral traits in children with ASD. Further longitudinal studies are needed to clarify causal relationships and support the development of microbiota-targeted interventions. Full article

Polymicrobial biofilms involving fungal and bacterial species are increasingly recognized as contributors to persistent infections, particularly in the oral cavity. Candida albicans and Aggregatibacter actinomycetemcomitans are two commensals that can turn into opportunistic pathogens and are able to form robust biofilms. Objectives: This study aimed to assess the interaction dynamics between these two microorganisms and to evaluate their susceptibility to fluconazole and azithromycin in single- and mixed-species forms. Methods: Biofilm biomass was quantified using crystal violet assays, while biofilm cell viability was assessed through CFU enumeration (biofilm viability assay). To assess the resistance properties of single versus mixed-species coincubations, we applied the antimicrobial susceptibility test (AST) to each drug, and analysed spatial organization with confocal laser scanning microscopy, using PNA-FISH. Results: The results indicated that both species can coexist without significant mutual inhibition. However, a non-reciprocal synergism was also observed, whereby mixed-species biofilm conditions promoted the growth of A. actinomycetemcomitans, while C. albicans growth remained stable. As expected, antimicrobial tolerance was elevated in mixed cultures, likely due to enhanced extracellular matrix production and potential quorum-sensing interactions, contributing to increased resistance against azithromycin and fluconazole. Conclusions: This study provides novel insights into previously rarely explored interactions between C. albicans and A. actinomycetemcomitans. These findings underscore the importance of investigating interspecies interactions within polymicrobial biofilms, as understanding their mechanisms, such as quorum-sensing molecules and metabolic cooperation, can contribute to improved diagnostics and more effective targeted therapeutic strategies against polymicrobial infections. Full article

Silicon has a striking similarity to carbon and is found in plant cells. However, there is no specific role that has been assigned to silicon in the life cycle of plants. The amount of silicon in plant cells is species specific and can reach levels comparable to macronutrients. Silicon is used extensively in artificial intelligence, nanotechnology, and the digital revolution, and thus can serve as an informational molecule such as nucleic acids. The diverse potential of silicon to bond with different chemical species is analogous to carbon; thus, it can serve as a structural candidate similar to proteins. The discovery of large amounts of silicon on Mars and the moon, along with the recent development of enzyme that can incorporate silicon into organic molecules, has propelled the theory of creating silicon-based life. The bacterial cytochrome has been modified through directed evolution such that it could cleave silicon–carbon bonds in organo-silicon compounds. This consolidates the idea of utilizing silicon in biomolecules. In this article, the potential of silicon-based life forms has been hypothesized, along with the reasoning that autotrophic virus-like particles could be used to investigate such potential. Such investigations in the field of synthetic biology and astrobiology will have corollary benefits for Earth in the areas of medicine, sustainable agriculture, and environmental sustainability. Full article

Streptococcus iniae (S. iniae) is a globally significant aquatic pathogen responsible for severe economic losses in aquaculture. While the S. iniae infection often exhibits distinct seasonal patterns strongly correlated with water temperature, there is limited knowledge regarding the temperature-dependent immune evasion strategies of S. iniae. Our results demonstrated a striking temperature-dependent virulence phenotype, with significantly higher A. latus mortality rates observed at high temperature (HT, 33 °C) compared to low temperature (LT, 23 °C). Proteomic analysis revealed temperature-dependent upregulation of key virulence factors, including streptolysin S-related proteins (SagG, SagH), antioxidant-related proteins (SodA), and multiple capsular polysaccharide (cps) synthesis proteins (cpsD, cpsH, cpsL, cpsY). Flow cytometry analysis showed that HT infection significantly reduced the percentage of lymphocyte and myeloid cell populations in the head kidney leukocytes of A. latus, which was associated with elevated caspase-3/7 expression and increased apoptosis. In addition, HT infection significantly inhibited the release of reactive oxygen species (ROS) but not nitric oxide (NO) production. Using S. iniae cps-deficient mutant, Δcps, we demonstrated that the cps is essential for temperature-dependent phagocytosis resistance in S. iniae, as phagocytic activity against Δcps remained unchanged across temperatures, while NS-1 showed significantly reduced uptake at HT. These findings provide new insights into the immune evasion of S. iniae under thermal regulation, deepening our understanding of the thermal adaptation of aquatic bacterial pathogens. Full article

Microbiome analysis has revolutionized our understanding of various biological processes, spanning human health and epidemiology (including antimicrobial resistance and horizontal gene transfer), as well as environmental and agricultural studies. At the heart of microbiome analysis lies the characterization of microbial communities through the quantification of microbial taxa and their dynamics. In the study of bacterial abundances, it is becoming more relevant to consider their relationship, to embed these data in the framework of network theory, allowing characterization of features like node relevance, pathways, and community structure. In this study, we address the primary biases encountered in reconstructing networks through correlation measures, particularly in light of the compositional nature of the data, within-sample diversity, and the presence of a high number of unobserved species. These factors can lead to inaccurate correlation estimates. To tackle these challenges, we employ simulated data to demonstrate how many of these issues can be mitigated by applying typical transformations designed for compositional data. These transformations enable the use of straightforward measures like Pearson’s correlation to correctly identify positive and negative relationships among relative abundances, especially in high-dimensional data, without having any need for further corrections. However, some challenges persist, such as addressing data sparsity, as neglecting this aspect can result in an underestimation of negative correlations. Full article

The gross benefit of feeding multi-species probiotics has been reported, but the effect on the gut microbiota in pre-weaned dairy calves has not been elucidated. To address this gap, a randomized controlled trial was conducted in California, USA, to investigate the effect of feeding probiotics on the fecal microbiota of pre-weaned dairy calves. A total of 30 neonatal calves were randomly assigned to either the probiotic (PRO) or control (CON) treatment. Fecal samples were collected at four age timepoints: days 7, 14, 21, and 42. Fecal bacterial population was analyzed using 16S rRNA amplicon sequencing. Differential abundance analysis was conducted to investigate the difference between the PRO and CON treatments, and diarrheic and non-diarrheic calves in each PRO and CON group. The PRO group had decreased Clostridium perfringens and Fusobacterium varium compared to the CON at 7 days of age. At 7 days of age, diarrheic calves in CON had more abundant F. varium compared to non-diarrheic calves, but there was no difference between diarrheic and non-diarrheic calves in the PRO group. In conclusion, probiotics administration decreased the population of pathogenic bacteria in feces from pre-weaned dairy calves on Day 7 of age. However, the treatment did not have an impact on bacterial diversity. These results suggest that the administration of probiotics has the potential to control gastrointestinal pathogens. Full article

Enterococcus spp. are opportunistic and nosocomial pathogens. Intensive pig farms have been recently described as important hotspots for antibiotic resistance and reservoirs of potentially pathogenic enterococci, including other species than the most known E. faecalis and E. faecium. Here, we identified Linezolid-resistant non-E. faecalis and E. faecium (NFF) Enterococcus strains isolated from different production stages (suckling piglets, weaning pigs, and fatteners) across six intensive pig farms. The transferability of the linezolid-resistance determinants was assessed by bacterial conjugation and strains were also characterized for biofilm production, hemolytic and gelatinase activity. Among 64 identified NFF Enterococcus strains, 27 were resistant to at least three different antibiotic classes and 8/27 specifically to Linezolid. E. gallinarum and E. casseliflavus both transferred their Linezolid resistance determinants to the main pathogenic species E. faecium. Remarkably, this is the first report of the optrA gene transfer from E. casseliflavus to E. faecium by conjugation, which can greatly contribute to the spread of antibiotic resistance genes among pathogenic enterococcal species. The “weaning pigs” stage exhibited a significantly higher number of antibiotic-resistant enterococci than the “fatteners”. These findings highlight the importance of monitoring pig farms as hotspots for the spread of antibiotic-resistant enterococci, especially in the early stages of production. Furthermore, they underscore the significant role of NFF Enterococcus species as carriers of antibiotic resistance genes, even to last-resort antibiotics, which may be transferable to the major enterococcal species. Full article