Search Results (17)

Regarding the trout microbiota, most information is focused on lactic acid bacteria, which can show beneficial properties. However, in trout farming, mostly pathogenic Gram-positive species were reported, such as Staphylococcus aureus, Listeria monocytogenes, and/or Clostridium spp. In this study, free-living trout were analyzed for Gram-negative microbiota that can cause loss as disease-stimulating agents. Bacteriocin postbiotics should be one of the approaches used to eliminate these agents. In total, 21 strains of different species isolated from the intestinal tract of 50 trout in Slovakia (Salmo trutta and Salmo gairdnerii) were taxonomically allotted into 13 species and 9 genera. This method showed variability in microbiota identified using MALDI-TOF mass spectrometry with the following species: Acinetobacter calcoaceticus, Citrobacter gillenii, Citrobacter freundii, Escherichia coli, Hafnia alvei, Kluyvera cryocrescens, K. intermedia, Leclercia adecarboxylata, Raoultella ornithinolytica, Pseudomonas fragi, Ps. putida, Ps. lundensis, Ps. teatrolens, and Serratia fonticola. Most strains were susceptible to the antibiotics used, reaching inhibitory zones up to 29 mm. On the other hand, 3 out of 21 strains (14%) were susceptible to nine enterocins- postbiotics (Hafnia alvei Hal281, Pseudomonas putida Pp391, and Ps. fragi Pf 284), with inhibitory activity in the range of 100–6400 AU/mL. Full article

Background: Urinary tract infections represent a significant healthcare burden, particularly among vulnerable patients with chronic comorbidities. In this case report, we describe a UTI caused by Kluyvera ascorbata exhibiting an AmpC resistance pattern in an 85-year-old male with stage IV chronic kidney disease and a history of ESBL-positive infection. Methods: A comprehensive diagnostic workup was performed, including clinical evaluation, laboratory tests (urinalysis, complete blood count, renal function tests), and microbiological cultures with antibiogram analysis using the MicroScan WalkAway (Beckman Coulter, Brea, United States) and VITEK2 Compact systems (bioMérieux, Marcy L’Étoile or Craponne, France). Results: The initial urine culture revealed a Gram-negative bacillus and subsequent identification confirmed K. ascorbata, which demonstrated resistance to ampicillin and cefazolin while remaining susceptible to meropenem. The patient received intravenous meropenem therapy for 10 days, resulting in clinical improvement and a subsequent negative urine culture. Conclusions: This case reports a complicated urinary tract infection caused by K. ascorbata with an AmpC resistance pattern, highlighting the importance of considering this infrequently reported pathogen and its resistance profile in vulnerable patients. Its multidrug-resistant profile underscores the necessity for vigilant antimicrobial stewardship and further research to develop standardized treatment protocols for managing infections caused by this organism. Full article

Excessive application of phosphorus (P) fertilizers does not alleviate P deficiency in soils and may cause water eutrophication. The available P in acidic soils is bound to minerals, such as iron and aluminum, in forms that are difficult to utilize by plants. The low availability of P is detrimental to soil health and crop growth. To address the P imbalance in the soil, different bioremediation techniques, such as phosphate-solubilizing bacteria (PSB) application, have been employed. However, the systematic analysis of the effects of composite inoculation of PSB on crops remains elusive. In this study, the effects of composite-inoculated PSB on plant growth were systematically evaluated by two scales: plate experiment and soil test. This study employed six different strains of PSB including Lelliottia amnigena 1-1 (A), Kluyvera intermedia 1-2 (B), Pseudomonas tolaasii 1-6 (C), Burkholderia cepacia 2-5 (D), Pseudomonas frederiksbergensis 2-11 (E), and Pseudomonas rhodesiae 2-47 (F). Among the 57 different combinations of these strains, four combinations (AE, AF, ADF, and AEF) indicated higher phosphate-solubilizing abilities than the single strains. These combinations were used for subsequent experiments. The plate experiment revealed that composite strains were more effective than single strains in promoting the growth and development of seedlings and roots of oilseed rape. Furthermore, AE, AF, and AEF combinations indicated excellent growth-promoting effects. Moreover, the soil test revealed that the composite inoculation of AE and AEF significantly enhanced biomass accumulation and root development in oilseed rape. The increased growth-promoting effects of the composite strains were observed to be associated with to their phosphate-solubilizing capacities. Both scales confirmed that compared to single inoculation, composite inoculation of PSB is more beneficial for plant growth. This study provides composite inoculation materials and foundational data to support the bioremediation of P imbalance in soil. Full article

This study aimed to evaluate the microbiological quality of coconut water sold from street carts equipped with cooling coils or refrigerated at bakeries in the Grande Vitória Region, Brazil. Additionally, it assessed the phenotypic and genotypic antimicrobial resistance profiles of isolated enterobacteria. The results indicated that coconut water sold at street carts had lower microbiological quality compared to refrigerated samples, as evidenced by significantly higher counts of mesophilic microorganisms. Using MALDI-TOF, the following opportunistic pathogens were identified: Citrobacter freundii, Enterobacter bugandensis, E. kobei, E. roggenkampii, Klebsiella pneumoniae, and Kluyvera ascorbata. Three isolates—E. bugandensis, K. pneumoniae, and K. ascorbata—were classified as multidrug-resistant (MDR). Widespread resistance to β-lactams and cephalosporins was detected, and some isolates were resistant to quinolones, nitrofurans, and phosphonic acids. The gene bla_CTX-M-2 was detected in C. freundii, E. bugandensis, E. kobei, and K. ascorbata. However, genes bla_NDM, bla_KPC, bla_CMY-1, and bla_CMY-2 were not detected in any isolate. The findings underscore the need to enhance good manufacturing practices in this sector to control the spread of antimicrobial resistance (AMR). To our knowledge, this is the first study documenting the presence of potentially pathogenic enterobacteria in coconut water samples and their associated phenotypic and genotypic AMR profiles. Full article

Research into microbial interactions during coffee processing is essential for developing new methods that adapt to climate change and improve flavor, thus enhancing the resilience and quality of global coffee production. This study aimed to investigate how microbial communities interact and contribute to flavor development in coffee processing within humid subtropical climates. Employing Illumina sequencing for microbial dynamics analysis, and high-performance liquid chromatography (HPLC) integrated with gas chromatography–mass spectrometry (GC-MS) for metabolite assessment, the study revealed intricate microbial diversity and associated metabolic activities. Throughout the fermentation process, dominant microbial species included Enterobacter, Erwinia, Kluyvera, and Pantoea from the prokaryotic group, and Fusarium, Cladosporium, Kurtzmaniella, Leptosphaerulina, Neonectria, and Penicillium from the eukaryotic group. The key metabolites identified were ethanol, and lactic, acetic, and citric acids. Notably, the bacterial community plays a crucial role in flavor development by utilizing metabolic versatility to produce esters and alcohols, while plant-derived metabolites such as caffeine and linalool remain stable throughout the fermentation process. The undirected network analysis revealed 321 interactions among microbial species and key substances during the fermentation process, with Enterobacter, Kluyvera, and Serratia showing strong connections with sugar and various volatile compounds, such as hexanal, benzaldehyde, 3-methylbenzaldehyde, 2-butenal, and 4-heptenal. These interactions, including inhibitory effects by Fusarium and Cladosporium, suggest microbial adaptability to subtropical conditions, potentially influencing fermentation and coffee quality. The sensory analysis showed that the final beverage obtained a score of 80.83 ± 0.39, being classified as a specialty coffee by the Specialty Coffee Association (SCA) metrics. Nonetheless, further enhancements in acidity, body, and aftertaste could lead to a more balanced flavor profile. The findings of this research hold substantial implications for the coffee industry in humid subtropical regions, offering potential strategies to enhance flavor quality and consistency through controlled fermentation practices. Furthermore, this study contributes to the broader understanding of how microbial ecology interplays with environmental factors to influence food and beverage fermentation, a topic of growing interest in the context of climate change and sustainable agriculture. Full article

A rising incidence of clinical infections has been caused by Kluyvera, a significant opportunistic pathogen. Meanwhile, Kluyvera acts as an important reservoir of bla_CTX-Ms, which are the dominant genes of class A extended-spectrum β-lactamases (ESBLs). In this work, 60 strains of Kluyvera were subjected to phylogenetic relationship reconstruction, antimicrobial susceptibility testing, and antibiotic resistance genes prediction. All mature bla_CTX-Ms were gathered to perform subgroup reclassification. The findings demonstrate that Kluyvera has a large gene pool with significant genetic flexibility. Notably, 25% of strains showed simultaneous detection of ESBLs and carbapenem resistance genes. The genotypes of fourteen novel bla_CTX-Ms were identified. A new subgroup classification approach for bla_CTX-Ms was defined by using 20 amino acid site variants, which could split bla_CTX-Ms into 10 subgroups. The results of the subgroup division were consistent with the phylogenetic clustering. More significantly, we proposed a novel bla_CTX-M subgroup, KLUS, that is chromosomally encoded in K. sichuanensis and the new species put forward in this study, showing amino acid differences from the currently known sequences. Cloning and transformation tests demonstrated that the recipient bacteria had a robust phenotype of cefotaxime resistance. Closely related Kluyvera species had bla_CTX-Ms in the same subgroup. Our research lays the groundwork for a deeper comprehension of Kluyvera and emphasizes how important a bla_CTX-M reservoir it is. We provide an update on bla_CTX-M subgroups reclassification from the aspects of phylogenetic relationship, amino acid differences, and the new subgroup KLUS, which needs to be strengthen monitored due to its strong resistance phenotype to cefotaxime. Full article

Fungus-growing termites are eusocial insects that represent one of the most efficient and unique systems for lignocellulose bioconversion, evolved from a sophisticated symbiosis with lignocellulolytic fungi and gut bacterial communities. Despite a plethora of information generated during the last century, some essential information on gut bacterial profiles and their unique contributions to wood digestion in some fungus-growing termites is still inadequate. Hence, using the culture-dependent approach, the present study aims to assess and compare the diversity of lignocellulose-degrading bacterial symbionts within the gut systems of three fungus-growing termites: Ancistrotermes pakistanicus, Odontotermes longignathus, and Macrotermes sp. A total of 32 bacterial species, belonging to 18 genera and 10 different families, were successfully isolated and identified from three fungus-growing termites using Avicel or xylan as the sole source of carbon. Enterobacteriaceae was the most dominant family represented by 68.1% of the total bacteria, followed by Yersiniaceae (10.6%) and Moraxellaceae (9%). Interestingly, five bacterial genera such as Enterobacter, Citrobacter, Acinetobacter, Trabulsiella, and Kluyvera were common among the tested termites, while the other bacteria demonstrated a termite-specific distribution. Further, the lignocellulolytic potential of selected bacterial strains was tested on agricultural waste to evaluate their capability for lignocellulose bioconversion. The highest substrate degradation was achieved with E. chengduensis MA11 which degraded 45.52% of rice straw. All of the potential strains showed endoglucanase, exoglucanase, and xylanase activities depicting a symbiotic role towards the lignocellulose digestion within the termite gut. The above results indicated that fungus-growing termites harbor a diverse array of bacterial symbionts that differ from species to species, which may play an inevitable role to enhance the degradation efficacy in lignocellulose decomposition. The present study further elaborates our knowledge about the termite-bacteria symbiosis for lignocellulose bioconversion which could be helpful to design a future biorefinery. Full article

The commercial production of poinsettias begins with the propagation of apical cuttings from stock plants. The aim of the study was to use bacterial mixtures prepared with PGPRs in the cultivation of stock mother poinsettia plants and determine an effective IBA dose to increase root development and root yield of cuttings prepared from these stock mother plants. Rooted cuttings of Euphorbia pulcherrima Willd.ex Klotzsch were used for planting stocks of mother plants. Eight different bacterial isolates were mixed in triple combinations to form 4 different bacterial formulations: (BI) formulation 1 (Paenibacillus polymyxa TV-12E + Pseudomonas putida TV-42A + Pantoea agglomerans RK-79); (BII) formulation 2 (Bacillus megaterium TV-91C + Pantoea agglomerans RK-92 + Bacillus subtilis TV-17C); (BIII) formulation 3 (Bacillus megaterium TV-91C + Pantoea agglomerans RK-92 + Kluyvera cryocrescens TV-113C); and (BIV) formulation 4 (Bacillus megaterium TV-91C + Pantoea agglomerans RK-79 + Bacillus megaterium TV-6D). In the first year, rooted cuttings of stock mother plants were dipped in liquid microbial solution (bacterial formulations) for 15 min and then planted in plastic pots. In the second year, the same bacterial formulations were freshly prepared and applied to the 1-year-old stock mother plants as irrigation water for the second time. Amounts of 0 (control), 1000, 1500, and 2000 mg L⁻¹ IBA doses were used for rooting cuttings taken from the 2-year-old stock mother plants. In the experimental group treated with the BI bacterial formulation, the number of rooted cuttings (NR) increased by 14.26% and 19.00%, compared with the control, in response to IBA 1500 mg L⁻¹ and IBA 2000 mg L⁻¹ treatment, respectively. Compared to the mean root length of the cuttings in the control treatment, the mean root length of the cuttings in the BIV treatment increased by 18.83%. The mean root length values decreased with the increase in IBA doses. The highest value of the number of mean shoots (NAS) was in cuttings treated with BI + 1500 treatment, which was 1.93 times higher than the control. The highest nitrogen content (5.73%) was determined in the bract leaf samples of the BIV application, and an 81.33% nitrogen increase was detected in the related application when compared to the control. In terms of P, Ca, and Fe contents, higher values were obtained from the BIV application when compared to the control application. The highest values of K content were determined in BIII and BII applications. This study provides positive effects on the feedback of stock mother plants with PGPR to provide sprout production by cuttings technique. It has been revealed that lower IBA dose applications can be recommended for rooting cuttings taken from mother plants treated with the BIV bacterial formulation. Full article

Locusts, in particular Locusta migratoria manilensis (Meyen), have been associated with major damages in agriculture, forestry, and animal husbandry in China. At present, L. migratoria manilensis has been largely domesticated, being considered an edible insect in China. Feeding variety is one of the main characteristics of L. migratoria manilensis. It has been demonstrated that microorganisms inhabiting the insect gut impact nutrition, development, defense, and reproduction of the insect host. The aim of the present study was to search for the adaptation mechanism of L. migratoria manilensis feeding on four different food plants (goosegrass, maize leaves, soybean leaves, and pakchoi) and explore changes in the gut bacterial community structure of the insect at the fifth instar nymph stage. Proteobacteria and Firmicutes were the dominant phyla, whereas Kluyvera, Enterobacter, Pseudocitrobacter, Klebsiella, Cronobacter, Citrobacter, Lactococcus, and Weissella were the dominant genera in the gut of L. migratoria manilensis. Principal component analysis and permutational multivariate analysis of variance (PERMANOVA) revealed significant differences in the gut microbiota structure of L. migratoria manilensis fed on different food plants. Moreover, functional prediction analysis revealed that metabolic and cellular processes were the most enriched categories. Within the category of metabolic processes, the most enriched pathways were carbohydrate transport and metabolism; amino acid transport and metabolism; translation, ribosomal structure, and biogenesis; cell wall/membrane/envelope biogenesis; inorganic ion transport and metabolism; and energy production and conversion. Collectively, the present results revealed that the structure of gut bacterial communities in L. migratoria manilensis fed on different food plants is impacted by food plants, which may play an essential part in the adaptation of the host. Full article

We used Illumina sequencing of the 16S rDNA V3-V4 region to identify the bacterial community in laboratory-reared G. gratiosa feces across different developmental stages (1st–7th instar nymph day 0, and 0-, 7-, 14-, and 21-day adult) and sexes. In total, 14,480,559 high-quality reads were clustered into 2982 species-level operational taxonomic units (OTUs), with an average of 481.197 (±137.366) OTUs per sample. These OTUs were assigned into 25 phyla, 42 classes, 60 orders, 116 families, 241 genera, and some unclassified groups. Only 21 core OTUs were shared by all samples. The most representative phylum was Proteobacteria, followed by Firmicutes, Bacteroidetes, and Acidobacteria. At the genus level, Kluyvera (387 OTUs), Obesumbacterium (339 OTUs), Buttiauxella (296 OTUs), Lactobacillus (286 OTUs), and Hafnia (152 OTUs) were dominant bacteria. The early-instar nymphs harbored a similar bacterial community with other developmental stages, which contain higher species diversity. Both principal coordinate analysis (PCoA) and non-metric multidimensional scaling analysis (NMDS) failed to provide a clear clustering based on the developmental stages and sexes. Overall, we assume that G. gratiosa transmits bacteria vertically by eating contaminated eggshells, and both developmental stages and sexes had no significant effect on the fecal bacterial community. Full article

Gram negative organisms are frequently isolated from Caretta caretta turtles, which can act as reservoir species for resistant microorganisms in the aquatic environment. C. caretta, which have no history of treatment with antimicrobials, are useful sentinel species for resistant microbes. In this culture-based study, commensal bacteria isolated from oral and cloacal samples of 98 healthy C. caretta were compared to clinical isolates from the wounds of 102 injured animals, in order to investigate the presence of AMR bacteria in free-living loggerheads from the Adriatic Sea. A total of 410 isolates were cultured. Escherichia coli and genera such as Serratia, Moraxella, Kluyvera, Salmonella were isolated only in healthy animals, while Acinetobacter, Enterobacter, Klebsiella and Morganella were isolated only from the wounds of the injured animals. When tested for susceptibility to ampicillin, amoxicillin + clavulanic acid, ceftazidime, cefuroxime, gentamicin, doxycycline, ciprofloxacin and enrofloxacin, the clinical isolates showed highly significant differences in AMR rates vs. commensal isolates for all the drugs tested, except for doxycycline. The detection of high AMR rates in loggerheads is of clinical and microbiological significance since it impacts both the choice of a proper antibiotic therapy and the implementation of conservation programs. Full article

Fixed-film biofilm reactors are considered one of the most effective wastewater treatment processes, however, the cost of their plastic bio-carriers makes them less attractive for application in developing countries. This study evaluated loofah sponges, an eco-friendly renewable agricultural product, as bio-carriers in a pilot-scale integrated fixed-film activated sludge (IFAS) system for the treatment of municipal wastewater. Tests showed that pristine loofah sponges disintegrated within two weeks resulting in a decrease in the treatment efficiencies. Accordingly, loofah sponges were modified by coating them with CaCO₃ and polymer. IFAS pilot tests using the modified loofah sponges achieved 83% organic removal and 71% total nitrogen removal and met Vietnam’s wastewater effluent discharge standards. The system achieved considerably high levels of nitrification and it was not limited by the loading rate or dissolved oxygen levels. Cell concentrations in the carriers were twenty to forty times higher than those within the aeration tank. Through 16S-rRNA sequencing, the major micro-organism types identified were Kluyvera cryocrescens, Exiguobacterium indicum, Bacillus tropicus, Aeromonas hydrophila, Enterobacter cloacae, and Pseudomonas turukhanskensis. This study demonstrated that although modified loofah sponges are effective renewable bio-carriers for municipal wastewater treatment, longer-term testing is recommended. Full article

The emergence and spread of mobile colistin (COL) resistance (mcr) genes jeopardize the efficacy of COL, a last resort antibiotic for treating deadly infections. COL has been used in livestock for decades globally. Bacteria have mobilized mcr genes (mcr-1 to mcr-9). Mcr-gene-containing bacteria (MGCB) have disseminated by horizontal/lateral transfer into diverse ecosystems, including aquatic, soil, botanical, wildlife, animal environment, and public places. The mcr-1, mcr-2, mcr-3, mcr-5, mcr-7, and mcr-8 have been detected in isolates from and/or directly in environmental samples. These genes are harboured by Escherichia coli, Enterobacter, Klebsiella, Proteus, Salmonella, Citrobacter, Pseudomonas, Acinetobacter, Kluyvera, Aeromonas, Providencia, and Raulotella isolates. Different conjugative and non-conjugative plasmids form the backbones for mcr in these isolates, but mcr have also been integrated into the chromosome of some strains. Insertion sequences (IS) (especially ISApl1) located upstream or downstream of mcr, class 1–3 integrons, and transposons are other drivers of mcr in the environment. Genes encoding multi-/extensive-drug resistance and virulence are often co-located with mcr on plasmids in environmental isolates. Transmission of mcr to/among environmental strains is clonally unrestricted. Contact with the mcr-containing reservoirs, consumption of contaminated animal-/plant-based foods or water, international animal-/plant-based food trades and travel, are routes for transmission of MGCB. Full article

Carbapenem-resistant Enterobacteriaceae have been a global public health issue in recent years. Here, a carbapenem-resistant Kluyvera cryocrescens strain SCW13 was isolated from hospital sewage, and was then subjected to whole-genome sequencing (WGS). Based on WGS data, antimicrobial resistance genes were identified. Resistance plasmids were completely circularized and further bioinformatics analyses of plasmids were performed. A conjugation assay was performed to identify a self-transmissible plasmid mediating carbapenem resistance. A phylogenetic tree was constructed based on the core genome of publicly available Kluyvera strains. The isolate SCW13 exhibited resistance to cephalosporin and carbapenem. bla_NDM-1 was found to be located on a ~53-kb self-transmissible IncX3 plasmid, which exhibited high similarity to the previously reported pNDM-HN380, which is an epidemic bla_NDM-1-carrying IncX3 plasmid. Further, we found that SCW13 contained a chromosomal bla_KLUC-2 gene, which was the probable origin of the plasmid-born bla_KLUC-2 found in Enterobacter cloacae. Phylogenetic analysis showed that K. cryocrescens SCW13 exhibited a close relationship with K. cryocrescens NCTC10483. These findings highlight the further dissemination of bla_NDM through clonal IncX3 plasmids related to pNDM-HN380 among uncommon Enterobacteriaceae strains, including Kluyvera in this case. Full article

The main objective of this study was to evaluate the genetic diversity and agricultural significance of bacterial communities associated with the surfaces of selected agronomic plants (carrot, cabbage and turnip). The bacterial diversity of fresh agricultural produce was targeted to identify beneficial plant microflora or opportunistic human pathogens that may be associated with the surfaces of plants. Bacterial strains were screened in vitro for auxin production, biofilm formation and antibiotic resistance. 16S rRNA gene sequencing confirmed the presence of several bacterial genera including Citrobacter, Pseudomonas, Pantoea, Bacillus, Kluyvera, Lysinibacillus, Acinetobacter, Enterobacter, Serratia, Staphylococcus, Burkholderia, Exiguobacterium, Stenotrophomonas, Arthrobacter and Klebsiella. To address the biosafety issue, the antibiotic susceptibility pattern of strains was determined against different antibiotics. The majority of the strains were resistant to amoxicillin (25 µg) and nalidixic acid (30 µg). Strains were also screened for plant growth-promoting attributes to evaluate their positive interaction with colonized plants. Maximum auxin production was observed with Stenotrophomonas maltophilia MCt-1 (101 µg mL⁻¹) and Bacillus cereus PCt-1 (97 µg mL⁻¹). Arthrobacter nicotianae Lb-41 and Exiguobacterium mexicanum MCb-4 were strong biofilm producers. In conclusion, surfaces of raw vegetables were inhabited by different bacterial genera. Potential human pathogens such as Bacillus cereus, Bacillus anthracis, Enterobacter cloacae, Enterobacter amnigenus and Klebsiella pneumoniae were also isolated, which makes the biosafety of these vegetable a great concern for the local community. Nevertheless, these microbes also harbor beneficial plant growth-promoting traits that indicated their positive interaction with their host plants. In particular, bacterial auxin production may facilitate the growth of agronomic plants under natural conditions. Moreover, biofilm formation may help bacteria to colonize plant surfaces to show positive interactions with host plants. Full article