Transcriptome of Stenotrophomonas bentonitica BII-R7 in response to 50 and 200 mM of selenate

Selenate (Se(VI)) is the most soluble and toxic species of Se. Stenotrophomonas bentonitica BII-R7 is able to resist high Se(VI) concentrations, coupling enzymatic reduction of Se(VI) to formation of less toxic trigonal (t)-Se. The results revealed a concentration-dependent response. Under 50 mM of Se(VI), many genes were highly induced, indicating that Se(VI)-resistance could be based on intracellular reduction to Se(IV), mainly through molybdenum-dependent enzymes, and antioxidant activity by enzymes like glutathione peroxidase. Although exposure to 200 mM provoked a sharp drop in gene expression, a time-dependent biotransformation process of reduction and formation of amorphous, monoclinic and t-Se(0) nanostructures was demonstrated, leading to long-term stable and insoluble t-Se(0) nanomaterials.