Influences of lithium on soil microbial biomass, bacterial community structure, diversity, and function potential

Lithium is an emerging contaminant, but there is little knowledge about its influences on soil microbial ecosystem. In this work, soils were treated with 10 to 1280 mg/kg lithium (Li10 to Li1280), and then microbial biomass assay and bacterial 16S rRNA high-throughput sequencing analysis were conducted to investigate the influences of lithium on soil microbial biomass, bacterial community structure and diversity, and predicted function potential. The results showed that lithium generally decreased microbial biomass carbon and the count of culturable microbe colony, reflecting the reduction in microbial biomass. However, microbial biomass nitrogen increased. Meanwhile, lithium altered bacterial community composition, structure, and dominance. The abundance of phylum such as Proteobacteria and Acidobacteria respectively increased and reduced under lithium stress, while genus such as Adhaeribacter dominated in control group to Li320, and genus such as Lysobacter dominated in Li640, Li960, and Li1280. Then, higher lithium treatments consistently inhibited the bacterial richness, evenness, and diversity, and caused community dissimilarity between groups and significant down-regulation of predicted pathways. Finally, the LEfSe cladogram distinguished several indicator bacteria for different lithium levels. Overall, the influences of lithium on soil microbial community depended on its content, and microbial biomass and richness were sensitive to lower lithium, while higher lithium varied bacterial community and predicted function potential more significantly. This study will provide microbial insights into understanding lithium contamination.