Journal of Microbiology最新文献

The global rise in obesity and its associated metabolic complications underscores the urgent need for safe and effective interventions. This study investigated the anti-obesity efficacy of a probiotic mixture containing Bifidobacterium breve BR3 and Lactiplantibacillus plantarum LP3 in C57BL/6 mice with high-fat diet (HFD)-induced obesity. After obesity was established by feeding a 60% kcal HFD, the probiotic mixture was administered orally for 4 weeks. Compared with the control group, mice receiving the L. plantarum LP3 and B. breve BR3 mixture exhibited significant reductions in body weight and total fat mass, as assessed by Dual-energy X-ray Absorptiometry (DXA) and Echo Magnetic Resonance Imaging (EchoMRI). The probiotic treatment also lowered serum Aspartate Aminotransferase (AST), Alanine Aminotransferase (ALT), and glucose levels, and attenuated lipid accumulation in both hepatic and epididymal adipose tissues. Transcriptomic profiling revealed upregulation of lipolytic genes (Sirt1, Pparα) and downregulation of lipogenic genes (Srebp1c, Fas), suggesting that the probiotic mixture promotes lipid catabolism while suppressing lipid synthesis. Additionally, serum adipokine levels were favorably modulated, indicating improved metabolic homeostasis. Gut microbiota analysis demonstrated an increased relative abundance of beneficial genera, including Akkermansia and Bacteroides, highlighting a microbiome-mediated contribution to the observed metabolic benefits. Overall, our findings indicate that the combined administration of Lactiplantibacillus plantarum LP3 and Bifidobacterium breve BR3 exerts multi-faceted anti-obesity effects by enhancing lipolysis, regulating lipid metabolism, and restoring a healthy gut microbial balance. This probiotic mixture represents a promising therapeutic approach for managing obesity and related metabolic disorders.

Sarcopenia is an age-related condition marked by a reduction in muscle mass and strength, and it is associated with impaired muscle regeneration and differentiation. While diseases like cardiovascular and chronic liver disease can induce sarcopenia, there is limited evidence regarding the specific diseases and mechanisms responsible for its development. In skeletal muscle, the loss of muscle mass is accompanied by a decrease in myofilament proteins and the inhibition of muscle differentiation in satellite cells. Bioactive compounds obtained from natural products have been traditionally used as therapeutics for diverse conditions. In this report, we investigated the effect of cinchonidine (CD) extracted from Cinchona tree on muscle differentiation of mouse satellite cells, and myoblast cell lines. CD significantly inhibited muscle differentiation by suppressing myotube formation and gene expression of myogenesis markers. In addition, CD reduced muscle differentiation by blocking phosphorylation of insulin receptor substrate 1 (IRS-1) during insulin-induced signal transduction. Therefore, the results show that CD, an antimalarial agent, inhibited muscle differentiation through the suppression of IRS-1 phosphorylation, suggesting that sarcopenia can be induced by CD.

Enterohemorrhagic Escherichia coli (EHEC) O157:H7 ATCC 43894 (also known as EDL932) has been widely used as a reference strain for studying the pathophysiology of EHEC. To elucidate the role of a large virulence plasmid pO157 and its relationship with acid resistance, for example, both EHEC ATCC 43894 and its pO157-cured derivative strain 277 were well studied. However, it is unclear whether or not these two strains are isogenic and share the same genetic background. To address this question, we analyzed the whole genome sequences of ATCC 43894 and 277. As expected, three and two closed contigs were identified from ATCC 43894 and 277, respectively; two contigs shared in both strains were a chromosome and a small un-identified plasmid, and one contig found only in ATCC 43894 was pO157. Surprisingly, our pan-genome analyses of the two sequences revealed several genetic variations including frameshift, substitution, and deletion mutations. In particular, the deletion mutation of hdeD and gadE in ATCC 43894 was identified, and further PCR analysis also confirmed their deletion of a 2.5-kb fragment harboring hdeD, gadE, and mdtE in ATCC 43894. Taken together, our findings demonstrate that EHEC ATCC 43894 harbors genetic mutations affecting glutamate-dependent acid resistance system and imply that the pO157-cured EHEC 277 may not be isogenic to ATCC 43894. This is the first report that such genetic differences between both reference strains of EHEC should be considered in future studies on pathogenic E. coli.

Pathogenic fungi pose major threats to both global food security and human health, yet the molecular basis of their virulence remains only partially understood. Beyond genetic and transcriptional control, emerging evidence highlights protein glycosylation as a key post-translational modification that governs fungal development, stress adaptation, and host interactions. Glycosylation regulates protein folding, stability, trafficking, and immune evasion, thereby shaping infection processes across diverse pathogens. While extensively studied in model organisms, our understanding of glycosylation in pathogenic fungi remains fragmented and lacks a coherent framework linking glycosylation dynamics to fungal development and pathogenicity. This review synthesizes recent advances from proteomic, transcriptomic, and glycomic studies in pathogenic fungi, focusing on interspecific variation in glycogenes and enzymes, hierarchical regulatory networks, and glycoprotein-mediated mechanisms of virulence. Finally, we outline current challenges and highlight glycosylation-targeted strategies as promising avenues for antifungal intervention.

Two aerobic, Gram-stain-negative, non-motile and rod-shaped bacterial strains designated GGG-R5T and M4-18T were isolated from flowers of golden wave (Coreopsis grandiflora) and rice paddy soil, respectively in the Republic of Korea. Both strains were pigmented and produced flexirubin-type pigments. Based on phylogenetic analysis using 16S rRNA gene sequence, both strains were placed within the genus Mucilaginibacter with M. agri R11T and M. jinjuensis YC7004T both being the closest relatives to GGG-R5T (97.7%) and in case of M4-18T, M. ginsenosidivorax KHI28T (98.5%) was the nearest neighbor. Characteristic to genus Mucilaginibacter, the major cellular fatty acids in both strains were iso-C15:0, iso-C17:0 3-OH, summed feature 3 (C16:1 ω7c and/or C16:1 ω6c); menaquinone-7 was the major menaquinone and phosphatidylethanolamine was the major polar lipid observed. Comparison of genome sequences with the other members of Mucilaginibacter indicated orthologous average nucleotide identity (orthoANI) at 73.3-73.5% for GGG-R5T and 78.9-88.5% for M4-18T. Digital DNA-DNA hybridization (dDDH) values ranged at 19.1-19.7% between GGG-R5T and its neighbor species. In case of M4-18T, the observed range was at 21.9-36.6%. Considering the 16S rRNA similarity, orthoANI and dDDH values as well as comparison of phenotypic and chemotaxonomic characteristics indicated that both strains belonged to genus Mucilaginibacter but were distinctly distinguishable from previously described species. The strains GGG-R5T and M4-18T, therefore represent distinct novel species for which names Mucilaginibacter florum GGG-R5T and Mucilaginibacter oryzagri M4-18T are proposed. The type strains are GGG-R5T (= KACC 22063T = JCM 36590T) and M4-18T (= KACC 22773T = JCM 35894T).

Collagenase and keratinase are two important proteolytic enzymes with recognized applications in biotechnology and medicine, particularly in the enzymatic removal of necrotic tissue and the control of infection. In the present work, a soil isolate of Bacillus subtilis strain AB2 (PX453297.1) was optimized for enzyme production under different nutritional and physicochemical conditions. The enzymes were recovered by ammonium sulphate precipitation and dialysis, examined by SDS-PAGE and zymography, and further assessed for pH and temperature optima, stability, the influence of metal ions, and kinetic parameters. Maximum collagenase activity (4.41 ± 0.22 U/ml) was observed at 37°C and pH 7.5 in a glucose-peptone medium, whereas keratinase production was enhanced between 37 and 40°C at pH 7.5 in lactose-peptone medium. Protein bands of approximately 55 and 33 kDa were detected, representing 6.2- and 5.5-fold purification. Collagenase showed an alkaline optimum (pH 10.0, 37-45°C) with Km 0.31% and Vmax 1.92 U/ml, while keratinase exhibited dual optima (pH 3.0 and ~7.0) with Km 0.27% and Vmax 0.84 U/ml. Biofilm assays revealed that collagenase reduced pre-formed biomass by 62-68% and viable counts by 1.1-1.7 log₁₀, clearly outperforming keratinase (41-57%, 0.7-1.2 log₁₀). When combined with conventional antibiotics, both enzymes potentiated activity, with notable synergy between collagenase and oxacillin against Staphylococcus aureus (FICI 0.31-0.37), ciprofloxacin against Pseudomonas aeruginosa (FICI 0.37-0.50), and meropenem against Klebsiella pneumoniae (FICI 0.28-0.44). These results indicate that B. subtilis AB2 produces collagenase and keratinase with distinct biochemical characteristics and strong antibiofilm properties, underscoring their promise as adjuncts in chronic wound care as well as in industrial applications.

Keratinase kerZJ is a multifunctional protease with potential as a feed additive and functional ingredient. Here we performed an integrated multi‑omics evaluation of its biosafety and impact on gut homeostasis in mice. Our findings confirm that kerZJ is well-tolerated, with no evidence of systemic toxicity or intestinal epithelial damage. Integrated transcriptomic and proteomic analyses revealed that kerZJ reinforces intestinal barrier integrity by upregulating extracellular matrix components, including collagen IV, and modulates mucosal immunity by enhancing B-cell activation and antimicrobial peptide defenses without inducing inflammation. Furthermore, kerZJ administration led to a significant upregulation of digestive enzymes and a dose-dependent increase in short-chain fatty acids production. Microbiome analysis showed that while high-dose kerZJ altered community composition, it enriched for beneficial taxa like Lactobacillaceae and did not induce dysbiosis. These results demonstrate that kerZJ safely enhances gut barrier function, promotes a favorable immune and metabolic environment, and fosters a resilient gut ecosystem, supporting its development as a safe feed additive and nutraceutical component.

The oral administration of synthetic drugs can effectively reduce blood lipid levels, but adverse reactions may occur. Because of this, the hypolipidemic ability of natural products has been increasingly investigated. We evaluate the safety and hypolipidemic characteristics of a water-soluble blue pigment extracted using HPD-400 resin from the fungus Quambalaria cyanescens. Hypolipidemic ability was examined by constructing a hyperlipidemia model with different doses of blue pigment (50, 100, and 200 mg/kg. mouse body weight) for 28 d. Blue pigment purity increased from 20.32% to 70.70% following treatment with HPD-400 resin. Acute toxicity tests revealed blue pigment sourced from Q. cyanescens to have no toxic effects on mouse body weight, mortality, or behavioral characteristics. Subacute toxicity tests revealed no significant differences in food intake, body weight, or organ weights between treatment groups and controls. Histopathological examination of the liver and kidney tissues of mice administered blue pigment were normal, and serum enzyme activities and blood constituents were also within normal ranges. Blue pigment can significantly reduce the weight of mice, reduce liver and kidney damage and fat accumulation. It can also reduce total cholesterol, triglyceride and low density lipoprotein cholesterol in serum and liver tissue, and increase the level of high density lipoprotein cholesterol. Reduce the levels of alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, creatinine, urea and uric acid in serum. Increase the activities of total superoxide dismutase, glutathione peroxidase and catalase in serum and liver tissue, reduce the content of malondialdehyde, and up-regulate liver lipase and lipoprotein lipase. Our work proves that blue pigment is nontoxic, has the function of reducing blood lipid, and can alleviate obesity-related symptoms by regulating lipid metabolism and oxidative stress.

Bladder cancer is the most common malignancy of the urinary tract and is a major health burden globally. Recent advances in microbiome research have revealed that the urinary tract harbors a resident microbial community, overturning the long-held belief in its sterility. Increasing evidence suggests that microbial dysbiosis and microbially derived metabolites contribute to bladder cancer carcinogenesis, progression, and therapeutic responses. Distinct microbial signatures have been observed in bladder cancer patients, with notable differences across disease stages and between primary and recurrent cases. Mechanistic studies have demonstrated that microbe-associated metabolites and toxins can drive DNA damage, chronic inflammation, extracellular matrix remodeling, and epithelial-mesenchymal transition. In addition, biofilm formation allows bacteria to evade immune responses and promotes persistent inflammation, creating a tumor-permissive niche. Beyond pathogenesis, microbial activity also influences therapeutic outcomes; for instance, some microbial pathways can inactivate frontline chemotherapy, while others generate metabolites with anti-tumor properties. Collectively, these patterns define a microbiota-metabolite-immunity axis, presenting opportunities for precision oncology. Targeting microbial pathways, profiling urinary microbiota, and harnessing beneficial metabolites offer promising advancements in biomarker discovery, prognostic refinement, and the development of novel therapeutic strategies for bladder cancer.

Two Gram-stain-positive, facultatively anaerobic, rod-shaped, and non-motile lactic acid bacterial strains, designated as strains CBA3605T and CBA3606T, were isolated from kimchi, a traditional Korean fermented food. Both strains were oxidase- and catalase-negative, non-spore-forming, non-hemolytic, and non-gas-producing. Optimal growth conditions for the two strains were observed at 30°C, pH 5.0, and 0% NaCl. The two genomes were composed of a circular chromosome and three plasmids and the DNA G + C content of 43.0%, respectively. Strains CBA3605T and CBA3606T were most closely related to Lactiplantibacillus (Lp.) pingfangensis 382-1T with 16S rRNA sequence similarity of 99.4% and 99.1%, respectively. However, the orthologous average nucleotide identities between CBA3605T and CBA3606T were 91.7%, and those with strain 382-1T were 76.9% and 76.5%, respectively. Digital DNA-DNA hybridization values between CBA3605T and CBA3606T were 45.0%, and those with strain 382-1T were 21.4% and 21.0%, respectively. The major fatty acids detected in both strains included C16:0, C18:1 ω9c, and summed features 7 (C19:1 ω7c, C19:1 ω6c, C19:0 cyclo ω10c, and/or C19:0 ω6c). The peptidoglycan of both strains CBA3605T and CBA3606T contained meso-diaminopimelic acid and was classified as A4α type (L-Lys-D-Asp). In polar lipid analyses, only strain CBA3605T contained aminophosphoglycolipid, which was absent in CBA3606T, although both strains harbored same major polar lipids (diphosphatidylglycerol, phosphatidylglycerol, and phosphatidylethanolamine). Based on phenotypic, phylogenetic, genomic, biochemical, and chemotaxonomic analyses, strains CBA3605T and CBA3606T represent two novel species of the genus Lactiplantibacillus, for which the names Lactiplantibacillus koreensis sp. nov. and Lactiplantibacillus kimchii sp. nov. are proposed, with CBA3605T (= KACC 81073BPT = JCM 37965T), and CBA3606T (= KACC 81074BPT = JCM 37966T) as the type strains.