Effects of Antimony (Iii and V) on the Biomarker Responses, and Microbial Diversity of Earthworm Eisenia Fetida (Savingy)

Abstract

The contamination of soils with heavy metal antimony (Sb) is becoming increasingly severe and widespread, and the ecological risks caused by it cannot be ignored. To evaluate how different Sb forms affect earthworms E. fetida (Savingy) (E. fetida) in soil, the biomarker response index (BRI), effect addition index (EAI), and microbial diversity were characterized after the single and joint application of Sb(III) and Sb(V). The results showed that both forms accumulated in earthworms. The metallothionein (MT) content in earthworm increased under Sb stress, with the superoxide dismutase (SOD), catalase (CAT), and glutathione S-transferase (GST) activities also showing an increasing trend. BRI decreased significantly with the increasing rate of Sb application. Additionally, EAI values were 0.25 and -0.07 under low and high application rates, respectively, thereby indicating that Sb(III) and Sb(V) had synergistic and antagonistic effects at low and high concentrations, respectively. The 16S rRNA sequencing results showed that Sb contamination affected microbial diversity, whereas earthworm activity affected the population evenness. According to taxonomic composition, the relative abundance of some bacterial taxa in the gut content and burrow lining changed significantly under Sb contamination. The principal component analysis (PCA) indicated that the Sphingobacterium faecium abundance increased with increasing Sb concentration. These results provide not only an important basis for the ecological risk assessment of Sb in the soil environment, but also new insights into the altered drilosphere bacterial communities under Sb stress.

Keywords: Sb(III), Sb(V), drilosphere, multiple biomarker responses, Microbial diversity