Carbohydrate based biostimulation regulates the structure, function and remediation of Cr(VI) pollution by SRBs flora

Abstract

Sulfate reducing bacteria (SRBs) have promising applications as important microorganisms in the microbial approach to remediation of soil heavy metal pollution. However, fewer studies have been conducted on the differences in community structure, community function, heavy metal remediation capacity and effects with SRBs cultured from different carbohydrate. In this study, we investigated the structure and function of different SRBs flora, the reduction mechanism of Cr(VI) and remediation effect on Cr(VI) contaminated soil through high throughput sequencing, ICP-OES analysis and a series of soil remediation experiments. The results showed that there were significant differences in the community structure and function of SRBs flora cultured with different carbohydrate, and glycerine cultivated community with high SRBs abundance, diverse community structure, complete community function, which realizing the best SRBs flora performance. This SRBs flora under the optimal carbon/sulfur ratio, Fe(II), and sodium chloride conditions of 2, 50–500 mg/L, and 0–2.5 %, respectively and the highest sulfate and Cr(VI) reduction rates reached 84.2 % and 73.6 %, respectively, which the hydrogen sulfide pathway was the dominant pathway for Cr(VI) reduction. The SRBs flora cultured with glycerine, lactate, and butyrate obtained a good community structure sulfate and Cr(VI) reduction rates in contaminated soils, which the restored seed germination function and significantly blocked the migration of Cr(VI) into plants. The study provides new technical idea to regulate the structure and function of SRBs flora by means of selecting carbohydrate for the efficient remediation of soil Cr(VI) pollution.