Letters in Applied Microbiology最新文献

Probiotics and paraprobiotics have the potential to alleviate kidney inflammation by modulating colitis and influencing the autophagy pathway. This study aimed to evaluate their effects on the autophagy pathway in kidney inflammation following colitis. Colitis was induced in mice using dextran sodium sulfate (DSS) to simulate gut inflammation. Molecular analysis quantitative PCR (qPCR) measured the expression of autophagy-related genes such as beclin, atg5, atg7, atg12, and atg13 in kidney tissue. DSS treatment significantly worsened colitis symptoms, increasing disease activity index and pathological scores while reducing colon length and weight. Treatment with probiotics and paraprobiotics improved these parameters and restored colon health. Moreover, DSS reduced autophagy gene expression in kidneys, whereas probiotic treatments significantly upregulated these genes, indicating an autophagy-inducing effect that helps mitigate colitis-associated kidney inflammation.

The isolation and identification of native lactic acid bacteria (LAB) from plant matrix and flowers, which are potential sources of novel strains for fermented food development. Accordingly, this study aimed to determine the presence and bacterial diversity in Hibiscus sabdariffa L. calyces, and to characterize their technological properties for potential food application. Nine isolates were identified by 16S rRNA gene sequencing, belonging to the genera Leuconostoc (JC1 and JC2), Bacillus (JC3), Limosilactobacillus (JC4), Lentilactobacillus (JC5 and JC6), Enterococcus (JC7 and JC8), and Lactococcus (JC9). Cell growth kinetics, lactic acid production, and pH reduction were used to characterize the isolated bacteria. Additionally, the technological potential of the isolates was evaluated by assessing their survival under refrigeration (4°C), freezing (-20°C), and pasteurization (both fast and slow) conditions. Susceptibility/resistance to 12 antibiotics was also determined. Results showed that isolate JC3 (Bacillus velezensis) exhibited outstanding growth parameters, tolerance to pasteurization thermal conditions (63°C/30 min and 72°C/15 s) and susceptibility to the 12 tested antibiotics. These results highlight the potential of Hibiscus calyces as a valuable source of diverse native LAB and related strains with promising technological traits. Further studies on the functionality and safety of these bacteria are required to confirm their probiotic potential.

Yersinia enterocolitica is a food-borne pathogen that causes yersiniosis, and its primary sources are animal-originated foods. This work aimed to analyze the effect of fresh pork meat juice (MJ) on planktonic and biofilm growth of Y. enterocolitica strains and to investigate the activity of some generally recognized as safe (GRAS) food preservatives. Twenty-eight Y. enterocolitica strains were used to test growth and biofilm formation in MJ, trypticase soy broth supplemented with 0.25% of glucose (TSBG) alone and in combination with 50% MJ (TSBG:MJ). All strains grew in MJ but most of them to lesser extent than in TSBG. Although TSBG:MJ was the most favorable medium for biofilm formation, many strains were able to form biofilm in MJ. To determine GRAS compounds activity, one B1A and one B1B Y. enterocolitica strain were selected. In nutrient broth with MJ, acetic acid was the most effective compound with MIC of 0.78 mg ml-1, MBC of 3.14 mg ml-1, and BIC of 1.57 mg ml-1 for both strains; for B1A strain, BBC was 12.56 mg ml-1 and for B1B strain, it was 25.12 mg ml-1. Although not all strains exhibited the same ability to form biofilms in MJ, it reduces the susceptibility of Y. enterocolitica to GRAS compounds.

The global increase in fungal infections and antifungal resistance has drawn attention to environmental sources of potentially pathogenic yeasts. This study investigated the fungal load and antifungal susceptibility of yeasts isolated from fresh fruits (strawberries, bananas, guavas, and apples) grown under organic and conventional farming systems. Samples were analyzed for total yeast counts (CFU g-1) and for quantification of yeasts capable of growing on medium supplemented with fluconazole (FLU) (8 and 64 µg ml-1), followed by phenotypic identification and antifungal susceptibility testing via broth microdilution. The highest fungal loads were observed in strawberries across both cultivation systems. While no differences were found between organic and conventional fruits, variation in total and FLU-tolerant yeast counts was observed between fruit types. Among 29 presumptively FLU-resistant isolates, 23 were confirmed as resistant by minimum inhibitory concentration testing. All isolates were resistant to itraconazole, and most showed cross-resistance to voriconazole. Identified species included Meyerozyma guilliermondii, Pichia kudriavzevii, Trichomonascus ciferrii, Papiliotrema laurentii, and Rhodotorula mucilaginosa, many of which are associated with invasive fungal infections. These findings highlight the potential of fresh fruits to act as reservoirs for opportunistic and multidrug-resistant yeasts. Enhanced microbiological surveillance of plant-derived foods is recommended as part of integrated public health strategies, particularly within the One Health framework.

Phosphorus (P) is an essential macronutrient for plant growth and development. However, most of the P in the Earth's crust is insoluble, making it inaccessible to plants. This review examines the ability of phosphate-solubilizing microorganisms (PSMs) to convert these insoluble forms of P into plant-accessible forms, highlighting their potential use as biofertilizers. PSMs mainly consist of phosphate-solubilizing bacteria and fungi, which play crucial roles in the soil P cycle. The mechanisms of P solubilization encompass not only the key components of the soil P cycle but also relate to PSM species and the presence of phosphatase/phosphohydrolysis-related genes. Organic P are mineralized by enzymatic activity, while inorganic P, such as iron-phosphate, aluminium-phosphate, and calcium-phosphate are solubilized through organic acid production, proton extrusion, siderophore secretion, and exopolysaccharide production. Additionally, arbuscular mycorrhizal fungi are among the PSMs that effectively enhance P uptake in plants. Using PSM inoculants as biofertilizers has shown promise in improving soil P availability. However, further research is needed to determine the optimal application conditions, including timing, inoculum forms, and dosages, to maximize their effectiveness.

Petrochemical spills present a global environmental challenge, necessitating effective monitoring and remediation. This study was designed to develop a molecular tool using binary functional gene ratios to assess contamination levels and timelines in petrochemical-contaminated soils. Soils from petrochemical-contaminated sites were collected and hydrocarbon quantification was performed using gas chromatography-mass spectrometry and two-dimensional gas chromatography with flame ionization detection, against specific standards. Metagenomic DNA was extracted, and functional genes associated with hydrocarbon degradation [PAH Ring-hydroxylating dioxygenase (PAH-RHDα) and 6-oxocyclohex-1-ene-1-carbonyl-CoA hydrolase (bamA)] were analysed using quantitative PCR (qPCR). A diagnostic ratio of PAH degradation genes was applied to characterize pollution. In-silico gene mining was used to verify the functional gene ratios. MS revealed distinct contamination profiles correlating with pollution duration and pollutant levels. One set of samples had kerosene concentrations between 154 and 478.64 µg/g of soil, while the other contained <11 µg/g. Functional genes analysis linked higher kerosene concentrations to increased Gram-negative dioxygenase levels and lower kerosene concentrations to Gram-positive dioxygenases. PAH-RHDα-GN: bamA and PAH-RHDα-GP: bamA reflected contamination levels and apparent pollution age. In-silico gene mining validated qPCR findings, confirming the reliability of gene ratios for environmental monitoring. Our findings show that the functional gene ratios serve as a molecular biomarker for spill characterization, offering a novel approach for assessing and monitoring contamination in soils.

Antimicrobial resistance (AMR) constitutes a significant global health threat, exacerbated using antimicrobials in aquaculture, which accelerates the spread of resistant bacteria. In fish and aquaculture water, Escherichia coli acts as a key reservoir and vector for AMR, facilitating the dissemination of strains resistant to critically important antibiotics such as carbapenems and colistin, often through the production of enzymes such as extended-spectrum ß-lactamases. This review aimed to synthesize recent findings on AMR patterns and associated genes in E. coli from fish and aquaculture waters globally. Studies indicate a high prevalence of resistant E. coli, with multidrug resistance to β-lactams, tetracyclines, quinolones, and sulfonamides. Common resistance genes identified include blaTEM, blaCTX-M, tet(A), sul1, and qnrS. The presence of bacterial strains harboring these resistance genes poses a significant public health risk through transmission in the food chain and the environment. The study concludes that tackling this challenge effectively demands robust surveillance, optimized aquaculture management, responsible antimicrobial stewardship, and a cohesive One Health framework aimed at reducing AMR in aquaculture and preserving public health.

The production of cellulase enzymes is crucial for converting lignocellulosic biomass into fermentable sugars, a process essential for various industrial applications. This study investigates the impact of mutagenesis on microbial growth in Pseudomonas species, specifically P. azotoformans, P. fluorescens, and P. lactis, isolated from maize cobs. Mutagenic agents, including ultraviolet (UV) radiation, ethidium bromide (EtBr), and nitrous acid (NA) were used to induce mutations, and bacterial growth was assessed over 8 days using Congo Red carboxymethyl cellulose medium. While EtBr mutagenesis significantly enhanced bacterial growth, particularly in P. azotoformans and P. fluorescens, with growth increases of up to 73% at 192 h compared to wild-type strains, cellulase activity was not directly measured in this study. UV and NA treatments showed only moderate or negative effects on growth. Although EtBr, a known carcinogen, raises safety concerns, its potential for improving microbial growth suggests it could be useful in optimizing strains for industrial applications. Further studies are needed to directly measure cellulase activity and confirm the impact of these mutagenic treatments on enzyme production.

The gut microbiota, which plays a vital role in synthesizing short-chain fatty acids (SCFAs), is involved in the pathogenesis of inflammatory bowel disease (IBD). This study aimed to evaluate four phyla of gut microbiota and main SCFAs in IBD patients compared to the control group. Stool samples from 40 IBD patients [including ulcerative colitis (UC) and Crohn's disease (CD)] and 20 healthy controls were analyzed. Quantitative polymerase chain reaction was used to assess the abundance of four major gut microbiota phyla, and SCFA concentrations were measured using high-performance liquid chromatography. Results showed that Firmicutes levels were significantly lower in both UC and CD patients compared to controls. Bacteroidetes were significantly reduced in CD patients, while proteobacteria were significantly elevated in UC patients. No significant differences were observed in Actinobacteria levels. Regarding SCFAs, butyric acid was significantly lower in both UC and CD patients. Additionally, acetic acid and propionic acid were significantly decreased only in UC patients. These findings highlight the presence of gut dysbiosis and altered SCFA profiles in IBD patients. Given the protective roles of gut microbiota and their metabolites, strategies to restore microbial balance and SCFA production may support the management and treatment of IBD.

Plant-based fermented foods offer an underexplored reservoir of probiotic strains with therapeutic potential. In this study, we isolated and screened lactic acid bacteria (LAB) from spontaneously fermented vegetables through a comprehensive in-vitro approach involving stress tolerance assays, antioxidant capacity, adhesion evaluations, and immune modulation studies using RAW 264.7 macrophages. Two standout strains, Lactiplantibacillus plantarum CRT01 (PP724070) and Levilactobacillus brevis CAB20 (PP499280), demonstrated strong resilience to gastrointestinal conditions, robust adhesion to Caco-2 cells, and significant free radical scavenging activity. Notably, both strains reduced reactive oxygen species and modulated LPS-induced inflammatory responses by downregulating TNF-α, IL-1β, IL-6, and IL-12, while enhancing IL-10 expression. This dual antioxidant-immunomodulatory action, along with their ability to exclude pathogens, produce short-chain fatty acids, and exhibit low antibiotic resistance indices, highlights their suitability as non-dairy probiotics for gut-targeted interventions against oxidative stress and inflammation-associated disorders.