Bioconversion of lignite humic acid by white-rot fungi and characterization of products

Abstract

Lignite humic acids (LHAs) were sequentially separated from lignite with aqueous NaOH and HCl and biotreated by an isolated fungus WF8. The liquid product (LP), residues (RS) and LHAs were analyzed using a Fourier transform infrared spectrometer (FTIR) and a proton nuclear magnetic resonance (1H NMR). Three main enzymes in WF8 (i.e., lignin peroxidase, manganese peroxidase and laccase) were also measured and analyzed with and without LHAs. The results show that LHAs can induce the ligninolytic enzymes. The oxidation and hydrogenation reactions proceeded to some extent, aromaticity in LHAs and carboxyl in LP decreased, and LHAs were converted into simpler LP via biochemical reactions by WF8.