A Novel Selenite-Reducing Bacterium Bacillus pseudomycoides SA14 Isolated from Se-Enriched Soil and Its Potential Se Biofortification on Brassica chinensis L.

Microbial participation in biofortification can improve the availability of selenium(Se) in soil and contribute to the enrichment of Se in crops. In this study, a selenite(Se(IV)) reducing strain was isolated from Se-rich soil, and its Se transformation and bio-enhancement ability were studied. The strain was identified as Bacillus pseudomycoides and could reduce more than 93.48% of 1.0 m M Se(IV) in 54 h. The results of scanning electron microscope(SEM) and energy dispersive Xray spectrometry(EDS) showed that Se(IV) was reduced to Se(0), and Se nanoparticles(Se NPs) were eventually formed. In pot experiments, B. pseudomycoides SA14 could promote the bioavailable Se in soils and the concentration of Se in Brassica chinensis L.. The concentrations of watersoluble Se, ion exchange Se and carbonate-binding Se in soil were increased by 23.13%, 22.05% and 30.89%, respectively. The Se concentration of Brassica chinensis L. in pot experiments was increased by 145.05%. The relative abundance of Bacillus in soil increased from 0.97% to 2.08% in the pot experiments. As far as we know, this is the first report of Se reduction by B. pseudomycoides. This study might provide a prospective strategy for microbial fortification of Se in crops.