Selenium Transformation Characteristics and Comparative Genomics Study of a Bacillus velezensis Producing SeNPs
In this study,a nano-selenium-producing Bacillus velezensis strain was isolated from animal feces,designated as N-8.This strain demonstrated remarkable selenium tolerance,reaching up to 32 mmol/L under liquid culture conditions.When exposed to 2 mmol/L selenium treatment,strain N-8 converted 73.63％of the sodium selenite in the medium into red nano-selenium within 12 hours,with a conversion efficiency reaching 90.54％after 72 hours.The produced nano-selenium had a particle size of 238.74 nm,rendering it a high-reduction-rate strain among Bacillus species.It was also found that N-8 showed obvious inhibitory effect on Salmonella,Staphylococcus aureus and Escherichia coli,three typical food-borne pathogens.Whole-genome sequencing and analysis revealed that the Bacillus velezensis N-8 genome is 3844241 bp in size,with a GC content of 45.61％,encoding a total of 3686 genes.The genome sequencing data have been submitted to NCBI and assigned the GenBank accession number JAZIAW000000000.Through antiSMASH prediction,14 gene clusters related to the biosynthesis of secondary metabolites were identified in the N-8 genome,of which 7 were identical or highly similar to those involved in the synthesis of macrolactin H,bacillaene,bacillibactin,bacilysin,difficidin,fengycin,surfactin.It indicating that the above secondary metabolites are the main reason for the antimicrobial effect of N-8.These findings provide a reference for the development and utilization of selenium-rich probiotic resources.
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