Brazilian Journal of Microbiology最新文献

The emergence and spread of Extended-spectrum β-lactamase (ESBL) producing avian pathogenic Escherichia coli (APEC) in poultry farms pose a significant challenge for the scientific community. The presence of APEC in poultry farms is linked to its ability to form biofilms, which is worsened by various virulence factors and drug resistance, enabling bacteria to survive in various environments. The present study investigated the prevalence of ESBL-producing APEC isolates from waste samples collected from poultry farms. A total of thirty samples were collected from ten poultry farms. One metallic sheen colony from Eosin methylene blue agar from each sample was used to isolate APEC. This study revealed that all twenty-eight E. coli isolates resisted at least one antibiotic, reflecting a high resistance rate. Isolates that resisted one or more antibiotics were further screened for APEC virulence genes via conventional polymerase chain reaction. The analysis revealed that 38% of the isolates were APEC strains, while the remaining 63% were non-APEC strains. Most APEC isolates harboured more than one beta-lactamase gene, with the prevalent ESBL genotype combination being blaSHV and blaTEM. Phenotypic confirmation using the Ceftazidime/Ceftadime + Clavulanic acid revealed that one isolate was found to produce the ESBL enzyme. To tackle this issue, it is important to implement preventative measures effectively, aiming to decrease the prevalence of ESBL-producing APEC and its transmission to humans via poultry products.

Immunomodulation by Lacticaseibacillus sp. is a subject of increasing interest; however, the time-period of administration for its immunomodulatory effect to occur is not well established. In the present study, we examined the effect of L. casei CB054 on cytokine transcription ex vivo in mouse splenocytes and the bacterial microbiota profile at 24, 48, and 72 h after oral administration of 1 × 10⁶ UFC/g viable L. casei. Cytokine mRNA transcription was evaluated for IL4, IL10, IL12, IFNɣ, and TNFα at different time points by qPCR. Microbiota was analyzed using fecal samples collected at zero, 24, 48, and 72 h after L. casei administration. A significant upregulation (p < 0.05) for IL10 at 72 h and IL12 at 48 and 72 h in supplemented groups was observed. IFNɣ and TNFα showed similar significant upregulation patterns (p < 0.05) at all time points evaluated, whereas IL4 showed significant transcriptional downregulation during the supplementation period. After DNA extraction, the V3-V4 region from the 16 S rRNA gene was sequenced, and reads were processed using the Divisive Amplicon Denoising Algorithm (DADA2). Bacteroides and Lactobacillus were the most abundant genera in the supplemented groups. At the phylum level, Actinobacteria and Bacteroidetes were reduced to 24 h and 48 h compared to 0 h, whereas the phylum Firmicutes significantly increased at 72 h compared to 0 h. In conclusion, evidence suggests that L. casei CB054 has a specific, time-dependent immunomodulatory effect on splenocyte cytokine transcription, modulating the bacterial communities of the mouse gut microbiome.

Chaetomorpha antennina is a green alga and is known for its medicinal properties. Endophytes are microbes capable of synthesizing bioactive compounds which kills the pathogens without harming the host. The current study was aimed to detect the presence of endophytic bacteria that could inhibit bacterial human pathogens. The isolate VITSSSTJ4 produced secondary metabolites that restrained the development of Bacillus cereus, Pseudomonas aeruginosa, and Escherichia coli with a zone diameter of 19 ± 0.67, 13 ± 0.67 and 12 ± 0.67 mm respectively, in n-hexane extract. Additionally, SPE and UPLC were used to purify the extract and a peak was detected in UPLC at a retention time of 7.741 min. Further, FT-IR technique was employed to detect the functional groups such as C-O, O-H, N=C=O, C=C, C-H, O-H, and N-H. Gass Chromatography-Mass Spectrometry (GC-MS) confirmed molecular mass of the lead molecule to be 369.1638 g/mol and was identified to be 1-(4-Acetamidoanilino)-3,7-dimethylbenzo [4,5]imidazo[1,2-a]pyridine-4-carbonitrile. The effective isolate VITSSSTJ4 was found to be the closest neighbour of Bacillus stercoris in 16S rRNA gene sequencing, and the rod-shaped cell structure of VITSSSTJ4 was detected by scanning electron micrographs. Molecular docking revealed that the lead molecule had a substantial binding interaction with the methyltransferase component with a binding affinity of -7.7 kcal/mol.

Plant-microbe interactions play a critical role in maintaining plant health, enhancing soil fertility, and sustaining ecosystem functionality. Agave americana (Asparagales, Asparagaceae, L.), a crassulacean acid metabolism (CAM) species known for its remarkable drought tolerance and diverse industrial uses, represents a valuable model for exploring the ecological and functional dynamics of these associations. This study explores the diversity and functional potential of bacterial communities associated with A. americana and their role in promoting plant growth. A combination of culture-dependent techniques and metagenomic sequencing was employed to isolate and characterize rhizospheric and endophytic bacteria. Prominent bacterial genera identified included Acinetobacter, Bacillus, Rhizobium/Mesorhizobium, and Microbacterium. Metagenomic analyses revealed a high abundance of Actinobacteria, Proteobacteria, and Chloroflexi, highlighting their roles in nutrient cycling and organic matter decomposition. Plant growth-promoting assays demonstrated that Rhizobium sp. 34 A produced significant levels of indole-3-acetic acid (IAA), enhancing nutrient availability and plant growth. Mesorhizobium sp. 28 A had the greatest overall impact, significantly increasing total fresh weight, chlorophyll content, and sugar profiles, surpassing the effects of chemical fertilizers. Furthermore, Bacillus sp. T12C12, in combination with other plant growth-promoting bacteria (PGPB), exhibited the highest nitrogenase activity, as measured through acetylene reduction assays (ARA). These findings suggest that bacterial inoculants can enhance the nutritional and agronomic value of Agave species, which are of significant agro-industrial and food importance, providing a sustainable alternative to chemical fertilizers. This study offers valuable insights into sustainable agricultural practices by leveraging microbial communities to enhance crop productivity and resilience.

Endophytes are unique organisms that may protect their host from abiotic and biotic stress and represent a hidden reservoir for biotechnological and diversity/taxonomic studies, mainly in a megadiverse country like Brazil. Andreadoxa flava, a remnant species of the Atlantic Forest with a single known tree, is considered extinct in the wild. Here, we assessed the culturable endophytic fungal community from leaves of this last remaining tree found in a cabruca agroforestry system. We obtained 296 isolates and a richness of 29 taxa based on morphology and DNA sequence analysis. Endophytes were classified in eight orders of Ascomycota Glomerellales (35.82%), Diaporthales (25.59%), Xylariales (21.95%), Botryosphaeriales (14.52%), Pleosporales (1.01%), Sordariales (0.67%), Hypocreales (0.33%), and Eurotiales (0.33%). The most dominant genera were Colletotrichum (105 isolates), Diaporthe (75 isolates), and Phyllosticta (41 isolates). The Shannon index (1st Collection: H = 2.434 and 2st Collection: H = 2.22) suggests a relatively high diversity. Additionally, we discuss the conservation implications of the fungal community in light of its host's imminent extinction. These results suggest that endophytic fungi associated with critically endangered plant species represent a promising frontier for mycodiversity, biotechnological exploration, and ecosystem conservation, offering a novel pathway to safeguard microbial diversity within threatened biomes.

Acidophilic sulfate-reducing bacteria (SRB) are anaerobic microorganisms capable of precipitating metals and raising pH levels in acidic drainage waters. Limited genera have been isolated from acidic sediments. This study aimed to characterize enrichment cultures of acidophilic SRB communities found in uranium mine sediments in Minas Gerais, Brazil. Enrichment tests evaluated lactate and acetate as electron donors across various pH levels. Results revealed SRB growth in both carbon sources at pH 3, 4, and 5, with sulfate removal rates of approximately 98% for lactate and 97% for acetate. Notably, Desulfosporosinus was abundant (27%) in both carbon source assays. In the acetate experiment, Acidocella, an acidophilic acetoclastic microorganism, dominated (39%), alongside Desulfosporosinus (27%). The latter, typically exhibiting incomplete metabolism, might use hydrogen or other forms of extracellular electron transfer (EET), potentially including direct interspecies electron transfer (DIET), in syntrophy with Acidocella spp. The predominance of Desulfosporosinus spp. and Clostridium spp. in the enrichment cultures also suggests a cooperative metabolic network in which fermentative bacteria play a critical role in initiating sulfate reduction under acidic conditions. These findings underscore the efficacy of the native acidophilic SRB enrichment strategy, both in recovering indigenous strains and in generating a functionally effective inoculum for sulfidogenic bioreactor systems, operating at low pH. This approach holds promise for treating Acid Mine Drainage (AMD) and merits further scalable research.

Aeromonas hydrophila is an emerging zoonotic foodborne bacterial pathogen that causes gastro-intestinal and extra-intestinal infections in humans. A total of 361 samples including water (n = 195) and foods of animal and aquatic origin (n = 166) collected from tribal dwelling areas of Northeastern India were screened for the microbiological presence of A. hydrophila. Upon presumptive identification and molecular confirmation, the overall occurrence was 8.31% (30/361) with the highest rate observed in edible snails (13/38, 38.24%), followed by fish (4/14, 28.57%), pork (5/18, 27.78%), chicken (5/100, 20.0%) and domestic tap water (3/195, 1.54%). Multidrug resistance was observed in 13.33% (4/30) of the isolates, with the highest phenotypic resistance observed against amoxicillin-clavulanic acid (15/30, 50.00%). Phenotypic virulence, ascertained using adhesion forming ability, identified five isolates with strong ability out of 76.67% (23/30) isolates which harboured the ability to form adhesions on abiotic surfaces. Serine protease (ser) gene featured as the predominant virulence gene (23/30, 76.67%) among the isolates followed by act (16/30, 53.33%) which codes for cytotoxic toxin. Heatmap analysis with hierarchical clustering as well as Enterobacterial Repetitive Intergenic Consensus (ERIC) and Random Amplified Polymorphic DNA (RAPD)-based fingerprinting indicated wide genetic diversity among the isolates. Overall, the study highlights the emergence and circulation of adhesion-forming, multidrug-resistant A. hydrophila strains that carry clinically important virulence genes. These findings raise a potential public health concern for the tribal population of Northeastern India, known for their distinct culinary practices and food habits.