Microbial adaptation in vertical soil profiles contaminated by antimony smelting plant
Abstract BackgroundSoil microbes play critical roles in the biogeochemical cycling of antimony (Sb) and arsenic (As), and the effects of Sb and As contamination on soil microbiota have been well documented in surface soils (< 0.2 m). However, their effects in deep soils remain poorly understood. This study determined the depth-resolved effects of Sb and As contamination on the microbial adaptation throughout soil profiles (0–2 m) and compared contaminated soil samples to uncontaminated samples.Methods16S rRNA amplicon sequencing and shotgun metagenomic sequencing were employed to investigate the microbial community and their metabolism traits in soil profiles. Co-occurrence network analysis was used to present the pairwise interactions of microbes.ResultsAs soil depth increased, Acidobacteria (18.8%–44.7% from top to bottom, hereafter), Chloroflexi (8.7%–42.4%), Proteobacteria (11.4%–27.1%), and Thaumarchaeota (0.49%–20.17%) were the most variable phyla from surface to deep soil. A set of co-occurrence networks revealed an obvious changing pattern of microbial interactions as soil depth increased. The networks were loosely connected in the heavily contaminated surface soil but gradually recovered and were well connected in the less contaminated deep soil. Results suggested that individual species became more connected with other patterns to perform syntrophic functions in the less contaminated soil depth. Shotgun metagenomic sequencing results indicated that microbial metabolic potential also changed with soil depth. Genes encoding C metabolism pathways were negatively correlated with Sb and As concentrations. A set of arsenic-related genes was enriched by the high Sb and As contamination but reduced with soil depth. ConclusionsSoil depth-resolved characteristics are often many meters deep and their microbial diversity and community structures obviously change along their vertical soil profiles due to different nutrient contents and biomasses. The significance of this study is that it further reveals how the microbial communities and microbial physiological traits respond to different soil profiles contaminated by high concentrations of Sb and As.