Biomineralization of Cd2+ and inhibition on rhizobacterial Cd mobilization function by Bacillus Cereus to improve safety of maize grains. (November 2021)

• Record Type: Journal Article
• Authors: Wang, Jun-Feng; Li, Wan-Li; Ahmad, Iftikhar; He, Bao-Yan; Wang, Li-Li; He, Tao; Wang, Fo-Peng; Xu, Zhi-Min; Li, Qu-Sheng
• Is Part Of: Chemosphere. Volume 283(2021)
• Publication Date: 2021-11
• Subjects: Cadmium pollution -- Cadmium resistant strain -- Agri-products safety -- Strain colonization -- Rhizosphere bacteria; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2021.131095
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: Reducing cadmium (Cd) bioavailability and rhizobacterial Cd mobilization functions in the rhizosphere via the inoculation of screened microbial inoculum is an environmental-friendly strategy to improve safety of crop grains. In this study, Bacillus Cereus, a model Cd resistant strain, was selected to explore its effects on Cd bioavailability and uptake, bacterial metabolic functions related to Cd mobilization. Results indicated that inoculation of Bacillus Cereus in maize roots of sand pot with water-soluble Cd (0.06–0.15 mg/kg) and soil pot with high Cd-contaminated soil (total Cd: 2.33 mg/kg; Cd extracted by NH4 NO3 : 38.6 μg/kg) could decrease water-soluble Cd ion concentration by 7.7–30.1% and Cd extracted with NH4 NO3 solution by 7.8–22.5%, inducing Cd concentrations in maize grains reduced by 10.6–39.9% and 17.4–38.6%, respectively. Even for a single inoculation in soil, Cd concentration in maize grains still satisfy food safety requirements (Cd content: 0.1 mg/kg dry weight) due to its successful colonization on root surface of maize. Bacillus Cereus could enrich more plant growth promotion bacteria (PGPB) and down-regulate the expression of genes related to bacterial motility, membrane transports, carbon and nitrogen metabolism in the rhizosphere soil, decreasing Cd bioavailability in soil. Approximately 80% Cd 2+ in media was transferred into intracellular, meanwhile Cd salts (sulfide and/or phosphate) were produced in Bacillus Cereus through biomineralization process. Overall, this study could provide a feasible method for improving safety of maize grains via the inoculation of Bacillus Cereus under Cd pollution. Graphical abstract: Image 1 Highlights: Bacillus Cereus decreases water soluble Cd concentration by 8–30% in sand pot. Single inoculation can ensure grains safety of maize in high Cd-contaminated soil. Bacillus Cereus inhibits expression of rhizobacterial genes related to Cd mobilization. Cadmium salts (Cd-S, Cd-P etc.) were formed with via biomineralization in medium.