Current Microbiology最新文献

To investigate the bacterial community structure and physicochemical characteristics of different types of Daqu in the Binzhou region, this study employed traditional pure culture methods, high-throughput sequencing technology, and conventional physicochemical assays for analysis. The research results indicate that Enterococcus faecium and Bacillus licheniformis emerged as the main LAB and Bacillus species in Daqu from Binzhou region, respectively. In addition, high-throughput sequencing revealed significant differences in bacterial community structure between the two types of Daqu (P < 0.01). Compostibacillus and Sebaldella were identified as the biomarkers and potential key strains of high- and medium-temperature Daqu, respectively, and high-temperature Daqu demonstrated higher microbial complexity and stability than medium-temperature Daqu. Physicochemical assays demonstrated that the a* value, Daqu skin hardness, Daqu core hardness, density, starch content, and aminophenol content being significantly higher in high-temperature Daqu (P < 0.05), meanwhile, the L* value, water activity, water content, protein content, liquefaction power, and saccharification power were found to be significantly lower in high-temperature Daqu (P < 0.05). And there was significant association between dominant genera and the physicochemical indexes of Daqu (P = 0.001). It can thus be seen that there were significant differences between the microbial communities and physicochemical indicators of different types of Daqu in the Binzhou region. The results of this study are of great significance for further analyzing the differences between different types of Daqu and improving their quality.

Infection caused by drug-resistant Staphylococcus aureus is a serious public health and veterinary concern. Lack of a comprehensive understanding of the mechanisms underlying the emergence of drug-resistant strains, it makes S. aureus one of the most intractable pathogenic bacteria. To identify mutations that confer resistance to anti-S. aureus drugs, we established a laboratory-based adaptive evolution system and performed 10 rounds of evolution experiments against 15 clinically used antibiotics. We discovered a panel of known and novel resistance-associated sites after performing whole-genome sequencing. Furthermore, we found that the resistance evolved at distinct rates. For example, streptomycin, rifampicin, fusidic acid and novobiocin all developed significant resistance quickly in the second round of evolution. Intriguingly, the cross-resistance experiment reveals that nearly all drug-resistant strains have varying degrees of increased sensitivity to fusidic acid, pointing to a novel approach to battle AMR. In addition, the in silico docking analysis shows that the evolved mutants affect the interaction of rifampcin-rpoB, as well as the novobiocin-gyrB. Moreover, for the genes we got in the laboratory evolution, mutant genes of clinical isolates of human had significant differences from the environmental isolates and animal isolates. We believe that the strategy and data set in this research will be helpful for battling AMR issue of S. aureus, and adaptable to other pathogenic microbes.

Comprehending the interplay between the microbial communities of bulk soil (BS) and rhizosphere soil (RS) holds crucial significance in maintaining soil health and fertility, as well as enhancing crop quality. Our research focused on examining these microbial communities in BS and RS of Acanthopanax senticosus, along with their correlation with soil nutrients, across three distinct habitats in Yichun, Heilongjiang Province. To achieve this, we employed high-throughput sequencing technology, specifically targeting the 16S and amplicon regions. The results showed that there were significant differences in soil nutrients, microbial diversity and composition between BS and RS in different habitats. Available phosphorus (AP), total nitrogen (TN), ammonium-nitrogen (NH₄⁺-N) and available potassium (AK) content in RS were higher than that in BS, but TP content was opposite. The Mantel experiment's findings revealed that the soil physicochemical attributes exerted a more significant impact on the microbial community present in RS compared to its influence in BS. Redundancy analysis (RDA) indicated that the bacterial community of BS was affected by SMC and TP. The fungal structure of BS was affected by soil moisture content (SMC), AP, AK (P < 0.01) and TN (P < 0.05). The fungal structure of RS was affected by soil organic carbon (SOC), AP and AK. A noteworthy inverse relationship was observed between Actinomycetes and SMC as well as AP. In conclusion, these results extend the understanding of soil microbial community of A. senticosus and provide a preliminary understanding of the effects of habitat changes caused by human activities on A. senticosus.

A novel Gram-negative, motile, rod-shaped bacterium, designated 4137-cl^T, was isolated from a thermal spring of North Ossetia (Russian Federation). Strain 4137-cl^T grew at 30-50 °C (optimum 42 °C) with 0-3.5% NaCl (optimum 0-0.3%) and within pH range 4.0-8.7 (optimum pH 6.8-7.3). It was a strictly anaerobic microorganism capable of fermentation and respiration on organic acids and proteinaceous substrates. Sulfur, sulfite, polysulfide, and arsenate were used as electron acceptors. In addition to heterotrophic growth it grew autotrophically with H₂/CO₂. The major fatty acids were C_16:1 ω8c and C_16:0. The size of the genome and genomic DNA G+C content of strain 4137-cl^T were 4.5 Mb and 59.2%, respectively. According to the 16S rRNA gene sequence and conserved protein sequences phylogenies, strain 4137-cl^T represented a distinct lineage of the family Acetonemataceae within the class Negativicutes. As inferred from the morphology, physiology, chemotaxonomical and phylogenomic analyses, strain 4137-cl^T ought to be recognized as a novel genus for which the name Anaeroselena agilis gen. nov., sp. nov., we propose. The type strain is 4137-cl^T(=KCTC 25383^T = VKM B-3575^T).

Translation initiation, which involves numerous protein factors and coordinated control steps, represents the most complicated process during eukaryotic translation. However, the roles of eukaryotic translation initiation factor (eIF) in filamentous fungi are not well clarified. In this study, we investigated the function of eIF2Bα in Aspergillus oryzae, an industrially important filamentous fungus. The ΔeIF2Bα mutants showed slow colony growth and decreased conidia production, suggesting the critical roles of eIF2Bα in the growth and development of A. oryzae. In addition, the loss of eIF2Bα significantly impaired the ability to produce amylase and kojic acid, indicating the involvement of eIF2Bα in the amylase synthesis and secondary metabolite production. Interestingly, the elimination of eIF2Bα improved the tolerance of A. oryzae to diverse adverse stresses, including endoplasmic reticulum stress, oxidative stress, cell wall-perturbing stress, and cell membrane-damaging stress. Overall, our results indicate that eIF2Bα is a crucial regulator of growth, development, stress response, amylase production, and kojic acid synthesis in A. oryzae.

A bacterial strain P1^T, capable of degrading diesel and converting thiosulfate to sulfate was isolated from an oil-contaminated soil sample. The cells were Gram-stain-negative, slightly curved rods and motile with a single polar flagellum. Growth of the strain was observed at 4-45 °C (optimum at 28 °C), at pH 4.0-12.0 (optimum at pH 10.0) and with 0-15.0% (w/v) NaCl (optimum at 2.0%). Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain P1^T was closely related to the members of the genus Limnobacter, with the highest sequence similarity to Limnobacter thiooxidans DSM 13612 ^T (99.8%), followed by Limnobacter alexandrii LZ-4 ^T (99.4%), Limnobacter parvus YS8-69 ^T (98.8%), Limnobacter litoralis KP1-19 ^T (97.6%), and Limnobacter humi UCM-39 ^T (97.5%). The draft genome sequence of strain P1^T was 3.40 Mb long, with a DNA G + C content of 52.4%. The average nucleotide identity and digital DNA-DNA hybridization values between strain P1^T and the closely related type strains were in the range of 71.8-85.1% and 18.1-28.7%, respectively. The predominant cellular fatty acids of strain P1^T included C_{16: 0}, summed feature 3 (C_{16: 1} ɷ7c and/or C_{16: 1} ɷ6c), summed feature 8 (C_{18: 1} ɷ7c and/or C_{18: 1} ɷ6c), and summed feature 7 (C_{19: 1} ɷ6c and/or C_{19: 1} ɷ7c and/or C_{19: 1} cyclo). In addition, the main polar lipid was composed of diphosphatidylglycerol, phosphatidylethanolamine, and phosphatidylglycerol. Q-8 was the sole respiratory quinone. Based on the polyphasic characterization, strain P1^T (= KCTC 72814 ^T = CCTCC AB 2019403 ^T) represents a novel species of the genus Limnobacter, for which the name Limnobacter olei sp. nov. is proposed.

Aquilaria malaccensis Lam., an Agarwood-producing tree native to Southeast Asia, secretes oleoresin, a resin with diverse applications, in response to injuries. To explore the role of endosphere microbial communities during Agarwood development, we utilized a metagenomics approach across three stages: non-symptomatic (NC), symptomatic early (IN), and symptomatic mature (IN1). The NC metagenome was dominated by Bacillus (19.15%), Klebsiella (13.25%), and Pantoea (12.46%) among bacteria and Saccharomyces (15.92%) among fungi. Notably, bacterial chemotaxis pathway genes were more prevalent in NC (2.14%) compared to IN (0.92%) and IN1 (1.16%), suggesting microbial chemotactic behavior. In the IN stage, Klebsiella (27.05%) and Saccharomyces (34.81%) were the dominant genera. The IN1 metagenome featured Pantoea (8.92%) and Neurospora (8.24%) as leading bacterial and fungal genera, respectively. Functional genes associated with defense mechanisms, lipid transport, and secondary metabolite biosynthesis were increasingly represented in IN1, indicating an enhanced microbial response as infection progresses. Ecological indices, including a high Shannon-Wiener index (H' = 4.467) and Simpson's dominance (1 - D = 0.9697), alongside Pielou's evenness index (J = 0.7034), highlighted a dynamic and diverse microbial community at the mature infection stage, reflecting the complex interactions within the Aquilaria endosphere during Agarwood formation.

Medicinal plants often harbour various endophytic actinomycetia, which are well known for their potent antimicrobial properties and plant growth-promoting traits. In this study, we isolated an endophytic actinomycetia, A13, from the leaves of tea clone P312 from the MEG Tea Estate, Meghalaya, India. The isolate A13 was identified as Streptomyces sp. A13 through whole genome sequencing (WGS) and 16S rRNA sequencing, showing 88% (ANI; Average Nucleotide Identity) and 99.78% sequence similarity with Streptomyces olivaceus. The strain A13 exhibited a prominent broad-spectrum antifungal activity against nine phytopathogens. It was observed that the ethyl acetate (EtAc) extract of A13 inhibits the spore germination rate of phytopathogen Nigrospora sphaerica (NSP) and also damages the fungal cell wall and cell structure. Additionally, the A13 strain exhibits several plant growth-promoting (PGP) traits, such as nitrogen fixation, ammonia production (4.7 µmol/ml), indole-acetic acid (IAA) production (8.91 µg/ml), siderophore production and 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity Gas chromatography mass spectrometry (GC-MS) analysis revealed that Phenol, 3,5-bis(1,1-dimethylethyl) was found to be the major chemical constituent in the EtAc extract of the A13 strain, accounting for 50.15% of the area percentage. Whole genome sequencing and subsequent genome analysis utilizing bioinformatics techniques such as Antibiotics & Secondary Metabolite Analysis SHell (antiSMASH) and Rapid Annotation using Subsystem Technology (RAST) revealed a wide array of biologically active secondary metabolite biosynthesis gene clusters (smBGCs) with different physiologically significant roles. These findings emphasize the potential of the A13 strain as a biocontrol agent with the capability to enhance plant growth and prevent diseases.

In the present study, the nematicidal and fungicidal activity of the biosurfactant (BS) produced by the strain Serratia ureilytica UTS was evaluated. The highest mortality of J2 juveniles of the nematode Nacobbus aberrans was 92.3% at a concentration of 30 mg/mL. Among the phytopathogenic fungi, the concentration of 1.0% of the crude extract of the biosurfactant was the one that obtained the highest percentage inhibition against the phytopathogens Fusarium oxysporum 72.2%, Fusarium sp., 80.2% and Alternaria solani 100% at 168 h of incubation. Analysis of the BS by GC-MS revealed the presence of the three amino acids alanine, homocystine and valine in its composition. As well as the presence of fatty acids: stearic acid, lauric acid and palmitic acid. With nuclear magnetic resonance (NMR) and mass spectrophotometry (MS) analysis, the crude extract was found to have the structure of a quaternary ammonium salt derived from stearic fatty acid, which is a component of the biosurfactant. Based on this evidence, it is suggested that the BS produced by S. ureilytica has a lipopeptide-like chemical structure and possesses nematicidal and fungicidal activity, and is therefore proposed for potential use and application as a biopesticide for the benefit of regenerative and sustainable agriculture.

Bovine mastitis is the most widespread disease that causes financial loss in the dairy industry. Staphylococcus aureus is a well-researched multidrug-resistant opportunistic bacterium that is frequently linked to subclinical mastitis and causes significant economic losses. A further problem in the management of S. aureus infections is its capacity to form biofilms; bacteria inside biofilms exhibit greater resistance to antimicrobials than planktonic cells. The most effective method for controlling mastitis is antibiotic therapy. Cloxacillin (CLX), ampicillin, and ceftiofur are currently the most often utilized drying treatments for dairy cattle. We have evaluated the therapy efficiency of cloxacillin-loaded chitosan nanoparticles (CLX-CS NPs) as well as the relationship between biofilm production, gene profile and the type of trial group (CLX and CLX-CS NPs) against S.aureus isolated from milk samples of cows diagnosed with subclinical mastitis. Investigation of phenotypic biofilm production showed that majority of the S. aureus isolates extracted from milk were producers of biofilm. Cloxacillin-loaded chitosan nanoparticles were able to significantly decrease the MIC (p < 0.05) and MBC values compared to cloxacillin. The relationship between the gene profile and the types of trial groups shows that coating cloxacillin with chitosan nanoparticles (CS-NPs) was able to reduce the MIC and MBC value in all nine gene profile groups. These findings indicate that administration of cloxacillin-loaded CS-NPs in the treatment of mastitis may improve cloxacillin therapeutic properties and could act as a potential alternative to the cloxacillin antibiotic for the treatment of bovine mastitis.