26 / 2023-04-29 10:45:45

Heterologous expression and enzymatic properties of laccase from Lignin-degrading strain Erwinia billingiae QL-Z3

lignin degradation, laccase,heterologous expression, enzymatic characteristics

Lignin is an important biomass energy and contains abundant aromatic base resources. Due to its complex structure, lignin is hard to degrade naturally and degradation of lignin has been widely studied. Laccase is an important lignin-degrading enzyme, belonging to superfamily of multicopper oxidases, which can degrade lignin with the assistance of copper ions. The enzymatic reaction of laccase is the initial step of lignin biodegradation. In our previous research, a lignin-degrading strain Erwinia billingiae QL-Z3 was screened. Whole genome sequencing revealed 4556 genes in the genome of QL-Z3 and 74 genes encoding extracellular enzymes are potentially involved in lignin degradation. In which the laccase gene ELac_205 from this strain was selected to elucidate its laccase activity. Therefore the mutant strain and complement strain of gene ELac_205 was constructed and the lignin degradation rate was measured. Then laccase was isolated and purified by heterologous expression and the optimum reaction condition of laccase was investigated . After gene knockout, the lignin degradation ability of QL-Z3 decreased 63.15%, while the complement strain showed almost the same lignin degradation ability as the wild type strain. In addition the activity of laccase is 219.00 U/L when ABTS was used as substrate and the optimum reaction condition of laccase is 50℃, pH=1. Overall, our results suggest that the enzyme has a good prospect in lignin-degrading. In conclusion, our study shows that Erwinia billingiae QL-Z3 and its laccase have potential applications in promoting the conversion of lignin into industrial chemicals, preparing high efficiency degradation agents or reducing lignin-related environmental pollution.