ABSTRACT
Microorganisms play an important role in Se transformations from soluble toxic forms to insoluble non-toxic Se(0), which is considered a promising technology for Se remediation. The biogenic SeNPs (BioSeNPs) are in stable colloidal spherical forms, quite different from their allotrope with crystalline structures. This chapter investigates the properties of the extracellular SeNPs produced by a model of Se(IV)-reducing bacterium Bacillus licheniformis in an effort to understand how these properties facilitate formation of BioSeNPs. Extracellular biomineralization of BioSeNPs is one of the significant detoxification mechanisms of toxic Se oxyanions. The presence of functional groups of carbohydrates and proteins on EPS produced SeNPs further verified extracellular Se(0) biomineralization mechanism, and thus further confirmed the layer on BioSeNPs might be from extracellular polymeric substances. The surface organic layers might make the spherical BioSeNPs stable in the colloidal suspension against crystallization.
