Coordination of bacterial biomarkers with the dominant microbes enhances triclosan biodegradation in soil amended with food waste compost and cow dung compost

Abstract

Increasing concerns regarding the micropollutant triclosan (TCS) derive from its potential threats to human health and ecological security. Compost addition have been verified to be effective in soil remediation, however, the biodegradation of TCS under compost amendment in soil remain unclear. This study investigated the removal of TCS in soils amended with food waste compost (FS), cow dung compost (CS) and sludge compost (SS), respectively, explored the key TCS-degraders and biological mechanisms of TCS removal. Compost addition significantly enhanced the removal of TCS (p < 0.05) in the order of FS > CS > SS. The dosage of 20% (w/w) was the most efficient one and the ultimate concentrations of TCS were decreased by 76.67%, 67.90% and 56.79% compared with CK, respectively. The abundance of key dominant bacterial genus (7 in FS and 4 in CS) and fungal genus (3 in FS and CS) was stimulated due to the increase of soil nutrient factors (including dissolved organic carbon, DOC; soil organic matter, SOM; ammonium nitrogen, NH4+; nitrate nitrogen, NO3−) and the decrease of pH. A negative correlation between these dominant microbes and TCS concentration indicated their potential effect on TCS degradation. A total of four bacterial biomarkers, namely Saccharomonospora, Aequorivita, Bacillaceae and Fodinicurvataceae (both at family level) were the key TCS-degraders. Structural equation model (SEM) indicated that the improvement of soil nutrient factors in FS and CS promoted TCS biodegradation by improving the activity of bacterial biomarkers, as while, the key dominant microbes showed good tolerance to TCS stress. However, there were no significant biological effects on TCS in SS group. Network analysis further confirmed that it was the coordination of bacterial biomarkers with the dominant microbes that enhanced TCS biodegradation in soil amended with food waste compost and cow dung compost.