Three bacterial strains efficiently reduce selenite to selenium nanoparticles in cell membranes

• Published in: BMC Microbiology
• Main Authors: Ruixia Li, Wenqiang Chen, Siyuan Huang, Daihua Jiang, Zhengjie Zhu, Chong Li, Xuejiao Huang
• Format: Article
• Language: English
• Published: BMC 2025-08-01
• Subjects: Antioxidant; Bio-nano selenium; Cell membrane; Selenite reduction
• Online Access: https://doi.org/10.1186/s12866-025-04304-w

Abstract Microbial synthesis of selenium nanoparticles (SeNPs) as a fertilizer can promote the development of selenium-rich agricultural products. However, most known selenium-reduction strains exhibit a tolerance to selenite of ≤ 100 mmol/L and possess relatively low reduction efficiency. In this study, three strains capable of tolerating selenite concentrations of > 300 mmol/L were screened from selenium-rich soil in Bama, Guangxi, China. Based on 16 S rRNA gene sequence analysis, the three strains were identified as Citrobacter sp.BM-1, Providencia sp.BM-2, and Brucella sp.BM-3. Notably, Brucella sp.BM-3 represents a novel selenium-reducing bacteria. All three strains reduced SeO3 2− to SeNPs on the cell membrane and subsequently released these nanoparticles outside the cells, forming spherical SeNPs with a particle size of 210–221 nm. Furthermore, qPCR analysis revealed that the selenium-reduction mechanisms in these strains primarily involve the glutathione pathway, which is catalyzed by nitrate reductase and sulfate reductase. These findings suggest that Citrobacter sp.BM-1, Providencia sp.BM-2, and Brucella sp.BM-3 are promising candidates for the synthesis of SeNPs.