Antonie Van Leeuwenhoek International Journal of General and Molecular Microbiology最新文献

Symbiotic bacteria are closely associated with insect adaptability and survival, particularly in species with nutritionally limited diets. In the tropical bed bug Cimex hemipterus, these microbial partners synthesize essential nutrients such as B vitamins and amino acids that are absent from blood meals. The global resurgence of bed bug infestations, fueled by increased international travel and insecticide resistance, has challenged conventional control methods. Microbial symbionts are increasingly suspected to contribute to resistance mechanisms, but their role remains poorly defined. This study investigated the impact of four insecticides—chlorfluazuron, tebufenozide, pyriproxyfen, and a combination of β-cyfluthrin and imidacloprid—on the culturable bacterial symbionts of C. hemipterus using surface contact bioassays at concentrations of 100, 500, 1000, and 10,000 parts per million (ppm). Results showed a statistically significant reduction in colony-forming units (CFUs) in treated groups (p = 0.01), with the greatest suppression observed at 10,000 ppm. A significant negative correlation was observed between CFU abundance and mortality in pyriproxyfen-treated groups (p = 0.005), suggesting a potential link between bacterial suppression and sublethal physiological effects. DNA sequencing identified Bacillus species—particularly B. cereus and B. thuringiensis—as predominant symbionts across all treatments, indicating core microbiota stability despite insecticidal stress. These findings highlight that while bacterial abundance can be reduced by insecticides, core symbionts persist, which may contribute to host resilience. This study provides foundational evidence for integrating symbiont-targeted strategies with existing chemical controls to improve bed bug management.

Stingless bee bread is a fermented bee pollen product containing beneficial lactic acid bacteria (LAB) with potential probiotic properties. This study aimed to characterise the probiotic potential and perform whole genome analysis of LAB isolated from the bee bread of two Indonesian stingless bee species, Tetragonula laeviceps and Heterotrigona itama. Four LAB isolates (BBAT2, BBST20, BBAH2, and BBAH7) were chosen for their ability to combat harmful bacteria, followed by molecular characterisation based on 16S rRNA gene sequence analysis, and identified as Lacticaseibacillus rhamnosus (BBAT2, BBAH2, and BBAH7) and Fructobacillus fructosus (BBST20). Probiotic properties of these isolates were further characterised by digestive tract simulations. Two selected LAB isolates with the highest viability under acidic conditions (80.96–102.10%), gastric juice (80.56–97.92) and bile salt (69.78–102.0%) were L. rhamnosus BBAH2 and BBAH7 followed whole genome sequence (WGS) analysis using PromethION Oxford Nano Technology (ONT). WGS revealed that Lacticaseibacillus rhamnosus BBAH2 (2,987,481 bp) and BBAH7 (2,987,282 bp) belong to the strain Lacticaseibacillus rhamnosus strain JCM 1136 (2,934,834 bp) with an average nucleotide identity (ANI) and ANI based on BLAST + (ANIb) values of 99.88–99 and 99.97% (> 95%), respectively. Genome mining analysis using antiSMASH version 8 beta 1 revealed two regions of biosynthesis gene clusters (T3PKS and RiPP-like), and BAGEL4 revealed one bacteriocin region (carnocin class). The results demonstrated that LAB isolates from stingless bee bread possess desirable probiotic properties and potential genomic characteristics. These strains provide a foundation for the further exploration of their applications in functional foods and nutraceuticals.

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This study aimed to isolate and identify lactic acid bacteria from traditionally fermented Makdous, with a focus on selecting strains suitable for safe and functional fermentation. A total of 33 isolates were identified by 16S rRNA gene sequencing as Levilactobacillus brevis (n = 29) and Lactiplantibacillus plantarum (n = 4). Technological characterisation, comprising acidification, exopolysaccharide production, and tolerance to salt, acid, and acetic acid, was followed by multivariate analysis, which identified five promising strains: Lev. brevis SB4 and Lp. plantarum SB6, SB12, SB14, and SB16. These strains, alongside the reference Lacticaseibacillus rhamnosus GG, were further evaluated for in vitro probiotic properties. Among them, Lev. brevis SB4 and Lp. plantarum SB14 stood out due to high autoaggregation, surface hydrophobicity, antioxidant activity, and antimicrobial effects. Notably, Lp. plantarum SB14 showed the highest radical scavenging activity, while SB4 demonstrated potent inhibition against Listeria monocytogenes ATCC 13932 and Staphylococcus aureus ATCC 43300. These findings suggest that SB4 and SB14 are strong candidates as multifunctional starters to enhance the safety, quality, and health-promoting potential of fermented vegetable products and other functional food applications.

Elucidating the relationship between biofilm formation and specific antibiotic resistance is important for understanding resistance mechanisms. In this study, the antibiotic resistance profiles of 64 coagulase-negative staphylococci (CoNS) strains isolated from intensive care patients were determined using the VITEK-2 compact system, and their biofilm production ability was assessed using the microtiter plate method to investigate the relationship between the two. Additionally, the minimum biofilm eradication concentrations (MBEC) of vancomycin, linezolid, trimethoprim/sulfamethoxazole, and ciprofloxacin were determined against isolates with varying biofilm production capacities. All the strains were susceptible to linezolid, teicoplanin, and vancomycin, while resistant to ampicillin, benzylpenicillin, and rifampicin. Resistance rates to other antibiotics ranged between 1.6% (quinupristin/dalfopristin) and 96.9% (oxacillin). Overall, 48.4% of the isolates produced biofilm. The biofilm production potential of Staphylococcus epidermidis strains (62.1%) was significantly higher than that of non-S. epidermidis CoNS strains (37.1%) (p < 0.05). No significant relationship was found between biofilm production and specific antibiotic resistance (p > 0.05). Contrary to the general literature, non-biofilm-producing strains were resistant to a greater number of antibiotics than biofilm-producing strains (p < 0.05). Crucially, MBEC values demonstrated a strong positive correlation with biofilm density, increasing up to > 1024 μg/mL in strong biofilm producers. The results indicate that biofilm production does not predict specific antibiotic resistance, and that non-biofilm-producing strains may have compensated for the lack of biofilm production by developing specific antibiotic resistance. However, biofilm formation confers significant phenotypic tolerance, necessitating much higher antibiotic concentrations for eradication than those indicated by conventional susceptibility testing. In addition to vancomycin, teicoplanin, and linezolid, daptomycin, tigecycline, trimethoprim/sulfamethoxazole, and quinupristin/dalfopristin were also found to be effective options for multidrug-resistant planktonic infections, though their efficacy against biofilm-embedded cells may be substantially limited.

Endophytic Bacillus species are known to improve legume symbiosis and plant performance through an array of mechanisms. This study evaluated the potential of endophytic Bacillus strains (B. firmus, B. subtilis, and B. tequilensis) to promote growth and productivity of chickpea (Cicer arietinum L) grown under rainfed conditions. Among the Bacillus strains evaluated for in vitro plant growth-promoting traits, B. firmus exhibited the highest potential for phosphate solubilization (pH drop to 5.0) and indole-3-acetic acid (IAA) production (28.9 PPM). Seed biopriming with Bacillus strains enhanced antioxidant accumulation in chickpea seedlings, with B. subtilis markedly boosting key antioxidant enzymes, while B. tequilensis and B. firmus exerted distinct tissue-specific effects, as revealed by principal component analysis (PCA). At the critical threshold of 20% polyethylene glycol (PEG 6000), which inhibit chickpea seed germination, B. firmus and B. tequilensis maintained viability and biopriming chickpea seeds with these strains restored germination (25% and 41.7%, respectively), whereas UnInoculated and B. subtilis bioprimed seeds failed to germinate. In a controlled pot study, B. firmus inoculation enhanced chickpea biomass, increasing root and shoot growth by 37.4% and 27.7%, respectively, over the UnInoculated control. Field study showed that co-inoculation of B. firmus with Mesorhizobium ciceri enhanced leghemoglobin content (79.6%), nodule biomass (69.0%), nutrient uptake (N: 13.8%, P: 20.3%), plant biomass (14%) and seed yield (8%) over the absolute control. Ordination analysis clearly indicated that co-inoculation of M. ciceri with B. firmus had the strongest effect on chickpea performance under field conditions. Our findings establish B. firmus as a promising bioinoculant for improving chickpea productivity under rainfed conditions.

Ganoderma is a diversified genus of wood decaying fungi known to cause diseases such as stem, butt, and root rot in economically significant trees and perennial crops. These fungi thrive on trees or logs and are identified by their glossy, reddish-brown appearance, accompanied by bitter taste. The Ganoderma genus encompasses a wide variety of bioactive constituents, such as polysaccharides, triterpenoids, and peptidoglycans, which underpin its potential health benefits. The distinctive features observed across different Ganoderma species render them valuable for numerous industrial and pharmaceutical applications. Despite much research over the years, taxonomy of the Ganodermataceae family is still complicated, with unresolved issues related to species identification, classification, and global distribution. Ganoderma is also a well-known phytopathogen responsible for diseases in crops such as coconut, oil palm, and areca nut, as well as in different forest trees. Although the genus is globally distributed, the majority of species are found in tropical and subtropical climates. Different Ganoderma species are acknowledged for their dual roles as both plant pathogens and sources of therapeutic and aesthetic benefits. This paper explores the life cycle, host range, infection mechanisms, and detection techniques, including laboratory-based methods (such as RAPD, RFLP, ELISA, FRET, DNA biosensors, TLS, and electronic nose technologies) and remote sensing. Furthermore, it outlines several potential strategies for disease management and control.

Advancing microbial bioprospecting is crucial for discovering novel sources of antimicrobial compounds (ACs). Members of the phylum Actinomycetota, particularly the genus Streptomyces, are renowned producers of a wide variety of bioactive metabolites, including several clinically relevant antibiotics. In the present study, 182 Brazilian actinomycete strains were screened for antimicrobial activity against major human pathogens, namely Staphylococcus aureus MRSA BMB9393, Pseudomonas aeruginosa ATCC 9027, Escherichia coli ATCC 11229, Aspergillus niger ATCC 16404, Candida albicans ATCC 10231, and Cryptococcus neoformans T1444. Among these, strain AM6-12 exhibited strong and broad-spectrum inhibitory activity. To optimize its metabolite production, AM6-12 was grown in various media (ISP-1, ISP-2, Mueller–Hinton, and glycerol-peptone broth) under submerged fermentation at 28 °C for 12 days. Supernatants were collected through centrifugation and filtration and tested via disk diffusion with 100, 150, and 200 μL volumes. Inhibition zones were measured after 36 h at 35 °C. Further experiments in ISP-2 medium under varying aeration conditions (180 vs. 210 rpm; different flask volumes) showed improved activity at 180 rpm, notably against MRSA (2.6 cm) and P. aeruginosa (1.25 cm), indicating oxygen availability influences metabolite synthesis. Genomic sequencing revealed a 7.88 Mb genome with a G + C content of 72.0 mol%. The 16S rRNA gene shared 100% identity with Streptomyces malaysiense MUSC 136, but multilocus sequence analysis (MLSA) of 16S rRNA, atpD, gyrB, rpoB, recA, and trpB showed divergence above the species threshold (MLSA distance > 0.007). Additionally, ANI (< 95%) and digital DNA–DNA hybridization (dDDH < 70%) supported its classification as a distinct species. These findings position AM6-12 as a promising novel Streptomyces species for antimicrobial production.

Antibiotic use in aquaculture prevents disease and promotes growth but can disrupt the gut microbiome and drive resistance. The study profiled the gut microbiome of antibiotic-treated Mystus cavasius using both culture-based and shotgun metagenomic approach. Culture-dependent analysis revealed a significant 2–threefold reduction in total viable bacterial count in treated fish. Phylogenetic analysis of 12 cultured isolates revealed treatment-driven enrichment of Bacillus, Enterobacter and Aeromonas. Antibiotic susceptibility testing further revealed increased resistance profiles among isolates from treated fish. Metagenomic profiling identified over 1400 bacterial species and revealed clear taxonomic shifts. Control groups were enriched with beneficial genera such as Lactiplantibacillus and Arthrospira, while treated fish were dominated by opportunistic or resistant taxa including Plesiomonas, Staphylococcus, and Acinetobacter. These shifts were further reflected at the phylum level, with a decline in Proteobacteria and Bacteroidetes, accompanied by an increase in Firmicutes and the enrichment of antibiotic-tolerant lineages. Treated samples exhibited more uniform alpha diversity indices, suggesting a restructuring of the microbial community hierarchy following oxytetracycline exposure, whereas beta diversity analysis showed a moderate separation between control and treated groups. These findings provide critical insights into the ecological and health risks of antibiotic use in aquaculture and underscore the importance of developing sustainable alternatives for disease management in fish farming.

Chronic alcohol consumption alters the composition of the gut microbiota, leading to dysbiosis, increased intestinal permeability, and systemic inflammation, which collectively contribute significantly to the pathogenesis of alcohol-related disorders, encompassing hepatic disease, metabolic abnormalities, immune dysfunction, and neuropsychiatric conditions. The complex interactions of alcohol with the gut ecosystem illuminate the fundamental mechanisms that result in the disruption of the gut-liver axis, the imbalance of microbial metabolites, and the emergence of leaky gut syndrome. The bidirectional gut-brain axis is similarly impaired, intensifying concerns related to addiction and cognitive deficits. Therapeutic strategies, encompassing probiotics, prebiotics, synbiotics, postbiotics, dietary alterations, and fecal microbiota transplantation, offer promising modalities for reinstating microbial balance and alleviating alcohol-induced damage. Cutting-edge treatments such as paraprobiotics and bacteriophage therapy further highlight the potential of microbiome modulation as a viable therapeutic strategy. This review underscores the urgent need for precision-targeted, microbiota-based interventions and calls for expanded clinical research to translate these insights into effective treatments for alcohol-associated disorders.

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