Perfluorohexanesulfonic acid (PFHxS) affected microbial interactions and functions by altering the rare microbial...

Perfluorohexanesulfonic acid (PFHxS), a persistent environmental pollutant, has been increasingly detected in soil environment. However, the mechanism underlying PFHxS-induced the nitrogen cycle and microbial defense and repair changes remains poorly understood. This study detected the effects of PFHxS (10 and 100 μg/kg) on microbial interactions, nitrogen cycle, as well as microbial defense and repair in soil using a microcosm experiment. PFHxS significantly changed the rare bacterial and fungal communities, directly altered the protistan community. PFHxS enhanced nitrogen cycle, selectively enriched nirK-type denitrifiers, and the rare microorganisms played a crucial role in mediating the interactions among these denitrifiers. Additionally, PFHxS activated antioxidant defense mechanisms to resist oxidative damages, with the responses being more pronounced at a concentration of 100 μg/kg. More important, PLS-PM analysis proved that the alterations in microbial interactions caused by PFHxS exposure directly and significantly affected the nitrogen cycle and antioxidant system, and their importance exceeded that of enzyme activity, gene abundance and the single microbial community. This study will prove useful for understanding the effects of PFHxS on microbial interactions and functions, highlighting the crucial role of rare microorganisms in driving microbial functions.