Journal of microbiology and biotechnology最新文献

As a chronic lipid driven arterial disease, dyslipidemia is one of the most critical risk factors for atherosclerosis (AS). The gut microbiota plays an important role in regulating host lipid metabolism disorders. Studies have shown that the herb "Gualou-Xiebai" (GLXB) can effectively regulate the blood lipid levels of ApoE ^-/- mice and inhibit blood lipid accumulation. However, it is not yet clear whether GLXB herb pair can alleviate lipid abnormalities in AS diseases by inhibiting cholesterol absorption. Meanwhile, the regulatory effect of GLXB herb pair on gut microbiota metabolites needs further research. Therefore, ApoE^-/- mice were used to establish a dyslipidemia model with a HFD approach, and the contents of the cecum of the mice were collected for a gut microbiota study and to analyze how the GLXB herbal pair ameliorates dyslipidemia through the gut microbiota in ApoE^-/- mice. The results showed that the GLXB herb pair can significantly increase metabolites propionic acid and butyric acid levels in the gut microbiota. In addition, cellular experiments demonstrated that butyric acid significantly reduced cholesterol levels in Caco-2 cells, and western blot results showed that the GLXB herb pair inhibited the expression of NPC1L1, ACAT2, MTP, and ApoB48 proteins by increasing the level of butyric acid. In conclusion, the GLXB herb pair exerts a therapeutic effect on dyslipidemia in ApoE ^-/- mice by decreasing intestinal cholesterol absorption in ApoE^-/- mice by increasing the level of butyric acid, a metabolite of the gut microbiota.

Mycobacterium abscessus complex (MABC) infections are among the most intractable challenges in clinical mycobacteriology because of their extensive intrinsic and acquired antibiotic resistance. Recent studies on compassionate use and a systematic 20-patient cohort study demonstrated that bacteriophage therapy is safe and generally well-tolerated, and it has been proven capable of inducing clinically meaningful improvements. Nevertheless, patient outcomes remain heterogeneous, largely because of antibody-mediated neutralization during intravenous administration and morphotype-dependent susceptibility, with smooth variants exhibiting resistance to currently available phages. Notably, phage resistance has rarely been observed in treated isolates, suggesting that durable efficacy is achievable when guided by pretreatment susceptibility screening. Emerging strategies, including phage engineering, lytic enzyme application, and liposomal encapsulation, are being developed to overcome intracellular barriers and immune clearance, whereas phage-antibiotic combinations have displayed synergistic activity. POSTSTAMP, the first prospective clinical trial, is establishing a structured framework for standardized evaluation. Collectively, these findings suggest that current compassionate use cases and small-scale cohorts provide a foundation for integrating bacteriophage therapy as a complementary strategy alongside antibiotics in future MABC treatment regimens.

Carbapenem-resistant Enterobacteriaceae (CRE), particularly Klebsiella pneumoniae, are major causes of severe systemic infections due to their resistance to most antibiotics and the high associated mortality, representing a growing global health concern. In this study, we report the in vivo efficacy of a novel probiotic strain, Lactiplantibacillus plantarum PMC105, against systemic CRE infections. In a mouse model characterized by neutropenia and antibiotic-induced gut dysbiosis, infection with carbapenem-resistant K. pneumoniae (CRKP) resulted in 60% mortality within two weeks. However, oral administration of PMC105 significantly reduced intestinal CRKP colonization, minimized body weight loss, and resulted in 100% survival. This therapeutic effect is presumed to result from enhanced gut barrier function, driven by upregulation of the tight junction protein ZO-1 in the ileum, thereby preventing bacterial translocation and subsequent systemic dissemination. In a therapeutic model of systemic infection following translocation, intranasal administration of PMC105 reduced bacterial loads in the stool, liver, kidneys, and lungs, improved clinical symptoms, and maintained body weight, thereby increasing survival rates. Comprehensive safety evaluations, including antibiotic susceptibility testing, hemolysis, bile salt deconjugation, D-lactate production, and cytotoxicity assays, confirmed the strain's safety. These findings support the potential of PMC105 as a dual-route microbiome-based therapeutic candidate for the treatment of systemic CRE infections and warrant further clinical investigation.

This study aimed to investigate the effect of Lactobacillus gasseri SBT2055 (LG2055) on non-alcoholic fatty liver disease (NAFLD). Mice were fed with high-fat diet (HFD) to establish NAFLD animal model. HFD mice were administrated with LG2055 gavage to explore the role of LG2055 on NAFLD. This study revealed that LG2055 gavage decreased serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), total cholesterol (TC), and triglyceride (TG), reduced lipid accumulation in liver tissue, promoted the expression of intestinal mucosal proteins mucin 2 (MUC2), defensin alpha 1 (DEFA1), and defensin alpha 4 (DEFA4), inhibited the levels of pro-inflammatory factors tumor necrosis factor-alpha (TNF-α) and interleukin (IL)-6, and increased the levels of anti-inflammatory factors IL-10 and immunoglobulin (Ig)A, IgG, and IgM. LG2055 decreased the abundance of Verrucomicrobota, Akkermansiaceae and Akkermansia while increased the abundance of Bacteroidota, Actinobacterota and Muribaculaceae. These findings implied that LG2055 alleviate liver damage caused by NAFLD by reducing hepatic lipid accumulation and gut homeostasis and regulating gut microbiota to inhibit intestinal inflammation, and increase immune regulation.

L-tryptophan (L-trp) is a key aromatic amino acid with significant industrial value, and microbial fermentation provides a sustainable alternative to traditional chemical synthesis. However, low production yields due to inefficient microbial strains remain a major challenge. In this study, we enhanced L-trp production through redox engineering of Escherichia coli TX1. Metabolomics analysis at various fermentation stages revealed dynamic changes in the metabolites of the aromatic amino acid pathway. A key bottleneck was identified in the shikimate pathway, where significant accumulation of chorismate and shikimate led to inefficient L-trp production. By optimizing the shikimate pathway, L-trp production was increased by 19.8%. Additionally, the continuous accumulation of phosphoenolpyruvate suggested a limitation in the supply of erythrose-4-phosphate, which participates in the same reaction. Redirecting carbon flux from fructose-6-phosphate toward erythrose-4-phosphate increased the precursor pool of erythrose-4-phosphate. To overcome nutritional limitations, exogenous addition of amino acids, vitamins, and salt ions to the fermentation medium was implemented. Systematic metabolic engineering and fermentation optimization led to a significant improvement in tryptophan production, achieving an 86.6% increase compared to the original level. This study lays a solid foundation for the future development of more efficient tryptophan-producing strains.

The purpose of this study was to evaluate the safety and efficacy of fecal microbiota transplantation in patients with constipation due to parkinson's disease. Gut dysbiosis has long been associated with parkinson's and recent studies have shown that FMT can restore the normal flora of the gut. Therefore, this clinical trial aimed to test the therapeutic efficacy of FMT in 5 patients aged 55 to 71 diagnosed with PD who presented with constipation. The study was conducted as an open label, prospective trial and consisted of FMT performed every 3 days via nasojejunal tube placement followed by 8 weeks of patient follow-up to evaluate response to drug therapy and to assess neurological function using UPDRS-III OFF scores, and improvement in constipation assessed with Wexner scores. Samples taken before and after FMT were collected for shotgun metagenomic sequencing to analyze the composition of the microbial communities present in patients. Untargeted non-targeted metabolomic studies were performed to investigate the impact of FMT on metabolome changes due to FMT. The results indicate an improvement in constipation and neurological functioning following FMT, and significant alteration of the gut microbiota. Significant increases in Bifidobacteria bifidus, Alistipes shahi, Anaerotruncus coli, and uncharacterized Flavonifractor were found post-treatment compared to the baseline. Many of the other strains present prior to treatment, including Acinetobacter sp. and Proteobacteria sp., had significantly decreased after the FMT. The metabolomic studies found shifts in metabolic pathways involved with unsaturated fatty acid synthesis and amino acid metabolism due to FMT. FMT may be an effective treatment option for constipation and neurological symptoms associated with PD.

Several Lactobacillus strains isolated from fermented food are expected to possess digestion supporting function as potential probiotics. However, the safety of Lactobacillus as functional food and its stability until consumption are often overlooked. To prevent potential side effects and maximize probiotic efficacy, it is essential not only to demonstrate the beneficial properties of candidate strain but also verify their safety and stability through a stepwise method. In this study, Lactobacillus strains were isolated from various fermented food and sequentially evaluated for safety, stability, and probiotic properties with a focus on digestive activity. First, five safety tests were conducted in accordance with WHO/FAO guidelines-antibiotic minimum inhibitory concentrations (MICs), hemolytic activity, bile salt hydrolase (BSH) activity, D-/L-lactate production, and cytotoxicity based on lactate dehydrogenase (LDH) released from human epithelial cells. Next, four stability tests were performed, including tolerance to heat, oxygen, and gastric acid/bile salts. In addition, adhesion ability to intestinal epithelial cells was examined as an indicator of colonization potential. Finally, probiotic properties related to assistance of digestion-lipase activity, protease activity, lactose and xylan utilization ability—were evaluated. Through this three-step evaluation, Lacticaseibacillus paracasei JL32-5 was proven to be a safe and stable probiotic resource supporting digestion of lipid, protein, lactose, and non-digestible carbohydrate therefore enhancing human wellness.

Streptococcus iniae is a gram-positive, spherical- or ovoid-shaped, facultative anaerobic bacterium and is one of the major species causing streptococcosis, resulting in economic losses in aquaculture. Endolysins, peptidoglycan hydrolases produced by bacteriophages, are emerging as replacements for antibiotics due to their specific lytic activity against pathogens. This study aimed to develop a novel endolysin, SinLys1930, that specifically targets and kills S. iniae. The molecular and structural characteristics of SinLys1930 were predicted based on bioinformatic approaches. The lytic activity of SinLys1930 was evaluated against S. iniae KCTC 3657 under various conditions, including different dosages, pH levels, temperatures, NaCl concentrations, and metal ions, to identify the optimal conditions, and its effectiveness was further tested in sterilized seawater. The conserved domain analysis revealed that SinLys1930 possesses two enzymatically active domains (NlpC/P60 and glucosaminidase superfamilies) with two cell wall-binding domains (CW-7 superfamily) positioned between them. The lytic activity of SinLys1930 was highest at pH 6.0 to 6.5 and temperatures between 16 and 37°C, and it was maintained even under high NaCl concentration. SinLys1930 reduced the optical density of S. iniae in sterilized seawater by approximately 60% after incubation for 1 h. Therefore, SinLys1930 could potentially serve as an alternative to antibiotics for preventing streptococcosis caused by S. iniae in the aquaculture industry.

This study investigated the bone-protective effects of Maillard reaction products (MRPs) from isolated soy protein and their fermentation product (MRPF) using Lacticaseibacillus rhamnosus IM18. In lipopolysaccharide-induced RAW264.7 cells, MRP showed enhanced antioxidant and anti-inflammatory activities compared to isolated soy protein, which were further improved by MRPF. In ovariectomized mice and RANKL-stimulated RAW264.7 cells, MRPF demonstrated superior anti-osteoclastogenic and bone-protective effects by suppressing osteoclast differentiation and preventing bone resorption. These effects involved downregulation of pro-inflammatory cytokines (Tnfa, Il1b, Il6, and Tnfs11) and upregulation of osteoprotegerin (Tnfrsf11b), along with restoration of intestinal barrier genes (Ocln, Cldn1, and Tjp1). MRPF administration significantly modulated gut microbiota, reducing inflammation-associated taxa (Desulfovibrio) while enriching beneficial genera (Bifidobacterium, Ruminococcus, and Akkermansia). Peptide profiling identified 28 bioactive peptides contributing to observed effects. These findings indicate that MRPF alleviates inflammation and maintains gut homeostasis, supporting its potential as a functional food ingredient for postmenopausal osteoporosis.

This study investigated the protective effects of the ethanolic extract of Eisenia bicyclis (EB) against chronic pulmonary toxicity induced by particulate matter (PM_2.5) exposure in mice. EB contains phlorotannins, including dieckol and phlorofucofuroeckol A, sulfated polysaccharides, and lipid and amino acid derivatives. Male BALB/c mice were exposed to aerosolized PM_2.5 for 5 h daily over a repeated-dose period, and EB was administered orally. The administration of EB significantly ameliorated PM_2.5-induced lung damage by restoring antioxidant defense systems and decreasing serum levels of inflammatory cytokines. EB also suppressed mitochondrial dysfunction and apoptotic signaling. Furthermore, EB attenuated the expression of inflammatory markers, including TLR4, TNF-α, IL-1β, and COX-2, and attenuated the activation of fibrotic signaling pathways via the TGF-β/Smad axis. In vitro experiments using A549 cells further supported these findings, demonstrating that EB and its phlorotannin components (dieckol, 6,6'-bieckol, and 6,8'-bieckol) restored cell viability, reduced inflammatory cytokines, and modulated the Nrf2/HO-1 pathway together with fibrotic genes and proteins. These findings suggest that EB, which contains bioactive compounds, may be a promising functional material candidate for mitigating chronic lung injury caused by environmental toxicants such as PM_2.5.