Perfluoroalkyl substances (PFASs) influence the structure and function of soil bacterial community: Greenhouse experiment

Environmental threats posed by perfluoroalkyl substances (PFASs) have received a great deal of attention in recent years. However, little is known about the influences of PFASs on microorganisms in the environment. In this study, several typical PFASs were selected, and their effects on bacterial communities were measured by Illumina MiSeq sequencing. The richness (Chao1 estimator), diversity (Shannon index) and community structure of the bacterial community changed after the exposure to PFASs (1 μg PFOS/g soil). The amendment of PFASs increased bacterial richness but decreased bacterial diversity, because PFASs stimulated the growth of some bacteria (e.g., Firmicutes, Acidobacteria and Actinobacteria) but inhibited other bacteria such as Latescibacteria and Chloroflexi. When low concentrations (0.01 μg/g and 0.1 μg/g) of perfluorooctane sulphonate (PFOS) were added, the promotion action was stronger than the toxic effect on soil bacteria. Conversely, the toxicity was stronger than the promotion action under high concentrations of PFOS (10 μg PFOS/g soil). PFASs pollution obviously disrupted the normal function of soil microorganisms. PFBS and PFHxS could activate sucrase and urease, while PFOS and 6:2FTS could inhibit these enzymes' activities. The reduction of soil functional genes also confirmed that PFOS, 6:2FTS and 6:2F53B inhibited soil enzyme activity and further destroyed the cellular structure, immune system and gene expression of soil bacteria. The effects of PFASs with long carbon chains on soil bacterial community and function was more obvious than that of short-chain PFASs.