Community-based ecological study on the reduction of soil Sb bioavailability by SRB+ remediation measures

The utilization of sulphate-reducing bacteria (SRB) in the production of sulphide (H2S) is widely recognized as a promising method for the stabilization of soil Sb(III) and Sb(V) through the generation of stable metal sulphide precipitates. However, despite its potential, the electron donor and acceptor effects and the ecological ramifications of the remediation process remain poorly understood. In this study, we employed the SRB strain Desulfovibrio desulfuricans to examine the mechanisms and ecological impacts of broad electron donors (humic acid, HA) and specific electron acceptors (sodium sulphate, Na2SO4) on antimony removal. The findings of this study indicate that the utilization of SRB, HA, and Na2SO4 all had a positive impact on the stabilisation of Sb. Notably, the SRB+HA treatment displayed the most effective stabilization of Sb, achieving a remarkable 58.40%. Additionally, it was observed that the presence of SRB had a significant impact on the bacterial community structure, with a pronounced homogeneous selection effect dominating the community assembly. The introduction of non-specific (HA) and specific (Na2SO4) enhancements stimulates the community in distinct directions. The former elicits a positive response from bacteria such as Acidovorax, Bacillus, and Flavobacterium, promoting systemic carbon sinks and electron supply, as well as enhancing heavy metal tolerance and carbohydrate degradation capacity. Conversely, the latter triggers a positive response from bacteria such as Acinetobacter and Comamonas, promoting the uptake of systemic sulfur sources and electron consumption, while enhancing heavy metal transformation and functions related to nitrogen and sulfur cycling. Overall, the results suggest that combining SRB and HA can be regarded as an effective strategy for remediating Sb-contaminated soils, thus providing a solid theoretical foundation for future soil habitat conservation efforts.