Frontiers in Microbiology最新文献

Introduction: Fusarium wilt, caused by Fusarium oxysporum f. sp. cubense (Foc), poses a significant global threat to banana cultivation. Conventional methods of disease management are increasingly challenged, thus making it necessary to explore alternative strategies. Bacterial endophytes, particularly from resistant genotypes, are gaining attention as potential biocontrol agents. Sphingobacterium thalpophilum, isolated from the resistant banana cultivar Pisang lilin (JALHSB010000001-JALHSB010000029), presents an intriguing prospect for combating Fusarium wilt. However, its underlying biocontrol mechanisms remain poorly understood. This study aimed to elucidate the antifungal efficacy of S. thalpophilum NMS02 S296 against Foc and explore its biocontrol mechanisms at the genomic level.

Methods: Whole genome sequencing of S. thalpophilum NMS02 S296 was conducted using next-generation sequencing technologies and bioinformatics analyses were performed to identify genes associated with antifungal properties. In vitro assays were used to assess the inhibitory effects of the bacterial isolate on the mycelial growth of Foc. To explore the biomolecules responsible for the observed antagonistic activity, metabolites diffused into the agar at the zone of inhibition between Foc S16 and S. thalpophilum NMS02 S296 were extracted and identified.

Results: Whole genome sequencing revealed an array of genes encoding antifungal enzymes and secondary metabolites in S. thalpophilum NMS02 S296. In vitro experiments demonstrated significant inhibition of Foc mycelial growth by the bacterial endophyte. Comparative genomic analysis highlighted unique genomic features in S. thalpophilum linked to its biocontrol potential, setting it apart from other bacterial species.

Discussion: The study underscores the remarkable antifungal efficacy of S. thalpophilum NMS02 S296 against Fusarium wilt. The genetic basis for its biocontrol potential was elucidated through whole genome sequencing, shedding light on the mechanisms behind its antifungal activity. This study advanced our understanding of bacterial endophytes as biocontrol agents and offers a promising avenue for plant growth promotion towards sustainable strategies to mitigate Fusarium wilt in banana cultivation.

Two physical treatments (heat via water bath and cold air) with various temperatures (20/70/75/80°C and - 80/-90°C) and exposure times (20, 30, 40 s) were carried out to identify a decontaminating effect on zoonotic pathogens on broiler carcasses. Subsequently, carcasses were analyzed for thermotolerant Campylobacter (C.), Salmonella, Escherichia (E.). coli and total colony count (TCC). Moreover, for the hot water treatment, qPCR with viable/dead differentiation (v-qPCR) was applied to detect viable but non-culturable cells (VBNC) of Campylobacter, referred to as intact but putatively infectious units (IPIU). Hot water immersion was tested on carcasses inoculated with C. jejuni and Salmonella, while cold air treatment was evaluated for naturally contaminated carcasses of broiler flocks colonized with Campylobacter. For hot water treatment, the statistically significant reducing effect was about 1 log₁₀ CFU/ml for both Salmonella and Campylobacter for 70-80°C and 20/30 s treatments. The effect of heat treatment for Campylobacter was smaller when samples were analyzed with v-qPCR with reductions of 0.5-0.8 log₁₀ IPIU/ml in mean. Cold air treatments at -90°C were effective in reducing the mean contamination level of Campylobacter by 0.4-0.5 log₁₀ CFU/ml at all exposure times (p < 0.05). Hot water treatments showed a decreasing trend on TCC by 0.6-0.9 log₁₀ CFU/ml (p < 0.05). TCC counts were not significantly affected by cold air treatment. For E. coli no statistically significant reductions were observed by hot water treatment. The cold air treatment at -90°C for 20 and 40 s led to a reduction of E. coli by 0.4 and 0.8 log₁₀ CFU/ml (p < 0.05), respectively. Treatment of carcasses with higher bacterial levels tended to show higher reduction. The research demonstrated that the efficacy of physical treatments for decontamination of broiler carcasses was more pronounced for hot water immersion than for cold air exposure. In conclusion, the results shed light on the potential application of these physical treatments in practice to reduce the quantitative load of contaminating pathogens to enhance food safety in the broiler meat production.

Although it is well known that the morphology of Gram-negative rods changes on exposure to antibiotics, the morphology of antibiotic-resistant bacteria in the absence of antibiotics has not been widely investigated. Here, we studied the morphologies of 10 antibiotic-resistant strains of Escherichia coli and used bioinformatics tools to classify the resistant cells under light microscopy in the absence of antibiotics. The antibiotic-resistant strains showed differences in morphology from the sensitive parental strain, and the differences were most prominent in the quinolone-and β-lactam-resistant bacteria. A cluster analysis revealed increased proportions of fatter or shorter cells in the antibiotic-resistant strains. A correlation analysis of morphological features and gene expression suggested that genes related to energy metabolism and antibiotic resistance were highly correlated with the morphological characteristics of the resistant strains. Our newly proposed deep learning method for single-cell classification achieved a high level of performance in classifying quinolone-and β-lactam-resistant strains.