Current Microbiology最新文献

Fusarium head blight (FHB), primarily caused by Fusarium graminearum, leads to severe contamination of wheat grains with the mycotoxin deoxynivalenol (DON), posing a significant threat to grain safety and quality. While chemical control remains common, its efficacy is increasingly challenged by fungicide resistance and potential stimulation of DON production. Biological control represents a promising alternative, yet the identification of effective antagonistic agents and elucidation of their mechanisms are still needed. This study evaluated the biocontrol potential of the endophytic bacterium Bacillus velezensis strain 6W1 against FHB and DON contamination. The crude antagonistic extract exhibited a clear dose-dependent inhibitory effect on the mycelial growth of F. graminearum. The EC₅₀ value was determined to be 210.79 µg/mL, and complete growth inhibition (100%) was achieved when the extract concentration reached 800 µg/mL. Likewise, DON biosynthesis was significantly suppressed in a concentration-dependent manner, with DON levels reduced to 0 at 800 µg/mL of the crude extract.Furthermore, macrolactin A was identified as the core antagonistic compound responsible for the observed antifungal activity. A field trial confirmed that strain 6W1 application significantly reduced FHB severity and DON accumulation in wheat grains. These findings demonstrate the potential of B. velezensis 6W1 as an effective biocontrol agent against FHB and provide a theoretical basis for its application in managing DON contamination.

Endophytic fungi represent promising sources of bioactive compounds with therapeutic potential. The biological effects of ethyl acetate extracts from two endophytic fungi (Aspergillus fumigatus and Pleosporales) isolated from Terminalia phanerophlebia root and bark tissues were examined in this study. Antimicrobial efficacy was evaluated using disc diffusion, minimum inhibitory concentration (MIC), and bactericidal/fungicidal assays against human pathogens. Both extracts demonstrated significant activity against multidrug-resistant Staphylococcus aureus (MRSA), with A. fumigatus showing superior potency (MIC: 15.6 µg/mL) and Pleosporales, 62.5 µg/mL. Antioxidant properties were assessed via 2,2-diphenyl-1-picrylhydrazy (DPPH) and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical scavenging assays, revealing dose-dependent activity with IC₅₀ values of 167.39 and 132.33 µg/mL for A. fumigatus, and 209.69 and 174.20 µg/mL for Pleosporales, respectively. Preliminary cytotoxic effects were measured using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, a tetrazole) assay on breast cancer (MCF-7), hepatocellular carcinoma (HepG2), and normal kidney (HEK 293) cells. Both extracts exhibited selective cytotoxicity against cancer cells with minimal effects on normal cells. Apoptotic induction was confirmed through ethidium bromide/acridine orange staining. Chemical profiling via gas chromatography-mass spectroscopy (GC-MS) and Fourier transform infrared (FT-IR) spectroscopy identified bioactive compounds, including pyrrolo[1,2-a]pyrazine derivatives, phenolic compounds, and ascorbic acid esters. These findings highlight the therapeutic potential of endophytic fungi from T. phanerophlebia as a source of antimicrobial, antioxidant, and potential anticancer agents. However, further investigations are needed to establish these findings in clinical studies.

Fermented cowpea is an important traditional fermented vegetable in China, widely consumed, particularly in southern regions. However, few studies have investigated the bacterial communities and flavor compounds in fermented cowpea, especially regarding the influence of salt concentration on microbial structure and metabolite dynamics. Therefore, this study investigated the effects of four salt concentrations (0%, 3%, 6%, and 9%) on microbial composition and metabolites in fermented cowpea. The results showed that 1-octen-3-ol, linalool, phenylethyl alcohol, 3-methyl-1-butanol acetate, 2-octanone, propanoic acid, 3-methyl-butanoic acid, benzeneacetaldehyde, and indole significantly contributed to the flavor of fermented cowpea. Lactobacillus, Acinetobacter, Pseudomonas, Muribaculaceae, and Bacteroides were the dominant bacterial genera. Furthermore, two-way orthogonal partial least squares (O2PLS) analysis revealed potential correlations between eight bacterial genera (Lactobacillus, Clostridium_sensu_stricto_1, Prevotella_9, Caproiciproducens, Bacillus, Lysinibacillus, Burkholderia-Caballeronia-Paraburkholderia, Pseudomonas, Acinetobacter, and Terribacillus) and nine characteristic flavor compounds, suggesting their significant impact on flavor profiles. Salt concentration was shown to influence both microbial composition and flavor characteristics. Additionally, the chemical profiles and bacterial communities of cowpea fermented with 3% salt were similar to those fermented with 6% salt. Fermentation at 3% salt concentration not only reduces production costs but also lowers health risks associated with high salt intake, providing an improved option for large-scale production.

This study addresses a critical knowledge gap by evaluating endophytes from Crocus sativus for a range of plant growth-promoting (PGP) activities and assessing their functional diversity using community-weighted mean (CWM) and functional diversity (FD) indices-an area that remains largely unexplored in plant-microbe interactions. We examined 84 potential endophytes for auxin production, ammonia and urease activity, phosphate solubilization, siderophore and amylase production, and antifungal properties. Endophytes belonging to Dothideomycetes exhibited only auxin production and urease activity, while members of other groups were positive for all assessed traits. FD indices varied significantly across sites and plant organs, with roots generally showing the highest values. The CWM of functional traits also differed among organs, with roots and corms displaying the highest values for auxin, ammonia, phosphate solubilization, and antifungal activity. Bacillus species, particularly B. cereus, were notable for auxin, amylase, and antifungal activities, while Streptomyces and Trichoderma strains also showed strong antifungal effects. Significant effects of site and organ type were observed for several functional traits, highlighting ecological variability across environments and plant parts. Additionally, endophyte responses to drought, temperature, and pH stress were assessed, with B. cereus, Streptomyces lydicus, and Trichoderma harzianum demonstrating superior growth under stress conditions. These findings advance ecological understanding of plant-endophyte interactions and suggest innovative strategies to enhance saffron yield and disease resistance in response to the growing challenges faced in saffron cultivation.

Vibrio hyugaensis is an opportunistic pathogen widely distributed in marine environments. Phages are considered an important method for controlling pathogenic bacteria. However, phages infecting V. hyugaensis have not yet been reported. In this study, a novel phage infecting V. hyugaensis, named vB_VhyS_SJ1, was isolated from nearshore surface seawater of Qingdao, China. Transmission electron microscopy showed that it had a siphoviral morphology. vB_VhyS_SJ1 exhibits a latent period of 10 min and a burst size of 52 ± 2 PFU/infected bacterium. It is stable over a temperature range of 4 °C to 65 °C and remains stable within a pH range of 5 to 10. The inhibition ability of the vB_VhyS_SJ1 against the V. hyugaensis was tested in vitro using the vB_VhyS_SJ1 with four multiplicity of infection (MOI) values. All treated groups effectively inhibited the growth compared to the untreated culture of V. hyugaensis within 12 h. The genome of vB_VhyS_SJ1 is double-stranded DNA, with a genome size of 121,361 bp, containing 174 putative open reading frames (ORFs). Four auxiliary metabolic genes (AMGs) were predicted, and a total of 25 tRNA genes were identified. Phylogenetic and genomic network analysis demonstrated that vB_VhyS_SJ1 belongs to the Pogseptimavirus genus of the Demerecviridae family. Additionally, biogeographical distribution analysis found that vB_VhyS_SJ1 is primarily found in temperate, and tropical epipelagic zones with low abundance. Overall, this study provides a characterization of the first phage infecting the opportunistic pathogenic V. hyugaensis.

Antimicrobial resistance (AMR) in Pseudomonas aeruginosa (PA) represents an escalating public health emergency in India, where factors such as unregulated antibiotic usage, limited infection control, and dense hospital environments have precipitated a dramatic rise in multidrug-resistant (MDR) and extensively drug-resistant (XDR) PA isolates. Recent Indian surveillance data indicate that resistance rates among clinical PA isolates often exceed 70% for key antibiotics, with carbapenem resistance surpassing 60% in intensive care settings and up to 98% for agents such as ceftriaxone in some cohorts. The World Health Organization designates PA as a critical-priority pathogen owing to its intrinsic and acquired resistance to nearly all available antibiotics, dramatically compromising patient outcomes, especially in high-burden regions like India. This review synthesizes the epidemiology of PA resistance in India, elucidating both the clinical prevalence and principal societal drivers-including over-the-counter antibiotic distribution and the prevalence of irrational fixed-dose combinations. A comprehensive analysis is provided of the molecular mechanisms underlying AMR in Indian PA isolates: the high prevalence of metallo-β-lactamases (e.g., blaNDM-1, blaVIM), overexpression of efflux pump systems (such as MexAB-OprM in over 50% of MDR isolates), porin loss (notably OprD in carbapenem-resistant strains), target site mutations, and widespread biofilm formation which affects up to 80% of device-related infections. Understanding these pathways is imperative for optimizing therapeutic regimens, informing antimicrobial stewardship, and directing research toward urgently needed new interventions for PA in India's unique clinical landscape. Additionally this review also talks about the various novel strategies which are currently in the development stages that can prove to be potent against PA in the future.