Humification process and mechanisms investigated by Fenton-like reaction and laccase functional expression during composting

Abstract

This study aims to explore the impacts of the Fenton-like reaction on hydrogen peroxide, hydroxyl radicals, humic substance (HS) formation, laccase activity and microbial communities during composting to optimize composting performances. The results indicated that the activity of laccase in the presence of the Fenton-like reaction (HC) (35.92 U/g) was significantly higher than that in the control (CP) (29.56 U/g). The content of HS in HC (151.91 g/kg) was higher than that in CP (131.73 g/kg), and amides, quinones, aliphatic compounds and aromatic compounds were promoted to form HS in HC by 2D-FTIR-COS analysis. Proteobacteria contributed most greatly to AA1 at phylum level, Pseudomonas and Sphingomonas abundances increased in HC. Redundancy analysis indicated that there was a strong positive correlation among the Fenton-like reaction, laccase and HS. Conclusively, the Fenton-like reaction improved the activity of laccase, promoted the formation of HS and enhanced the quality of compost.

Keywords: Composting; Fenton-like reaction; Humification mechanisms; Laccase; Microbial community succession.