Nitrate shifted microenvironment: Driven aromatic-ring cleavage microbes and aromatic compounds precursor biodegradation during sludge composting

Abstract

The aim of this study was to clarify the aromatic cleavage pathways and microbes involved in the adverse effect of nitrate on aromatic compounds humic substances during sludge composting. Results showed that the functional microbes involved in aromatic compounds humic substances precursors (catechol, tyrosine, tryptophan and phenylalanine) cleavage pathways significantly enriched after nitrate addition. Linear regression analysis showed that aromatic-ring cleavage functional microbes exhibited significant negative correlation with aromatic humic substances (p < 0.05). Furthermore, network analysis indicated that most of microbial communities prefer cooperative with aromatic-ring cleavage functional microbes. Structural equation model further revealed that composting microenvironment drove aromatic-ring cleavage functional microbes activities, resulting in the biodegradation of complex aromatic compounds. This study parsed the effect of a negative factor on aromatic compounds humic substances from an opposing perspective. Properly controlling nitrate concentration and aromatic-ring cleavage functional microbes involved in precursors cleavage was suggested to the practice of composting.