Selenium nanoparticle synthesis in Stenotrophomonas maltophilia: Mutagenesis and molecular mechanisms

Biosynthetic selenium nanoparticles (SeNPs) exhibit superior bioavailability and detoxification potential compared to inorganic selenium forms. In this study, the strain Stenotrophomonas maltophilia SE5, isolated from the feces of piglets (Duroc × Large White × Landrace), was utilized as the wild-type strain and subjected to atmospheric and room temperature plasma (ARTP) mutagenesis. A high-yielding mutant, Mu537, was successfully obtained, which exhibited an enhanced tolerance to sodium selenite, with its maximum tolerable concentration increasing from 1.0 g/L to 1.5 g/L. After 48 h of cultivation, Mu537 achieved an approximate 35% increase in SeNPs conversion rate and a 40% increase in SeNPs concentration relative to the parental strain. Integrated whole-genome sequencing and transcriptomic analysis revealed that pivotal genes associated with efficient SeNPs biosynthesis, including cysB, trxA, and sufE, were significantly up-regulated. These findings provide a systematic understanding of the potential molecular mechanisms driving enhanced SeNPs biosynthesis, offering both high-quality microbial resources and theoretical support for the industrial production of SeNPs.