New approach of bioprocessing towards lignin biodegradation

Bio-utilization of lignocellulosic biomass is of huge significance as it can directly replace petroleum resources by producing liquid fuels and organic chemical products in a more sustainable way. However, studies on developing lignin-degrading microbial resources are still very few, which affects on establishing a consolidated bioprocessing of lignocellulosic resource. The main aim of this work is to discover thermostable laccases for lignin thermo-biodegradation by metagenome-mining and biochemical characterization. Results indicate that 124 putative thermostable laccase genes were identified from generated metagenomes. Significantly, 3 rationally selected proteins showed actual activity and structural stability at temperatures up to 60 °C and pH values as low as 4.87. These active recombinant enzymes verify a practical advance in the functional prediction of target proteins, and simultaneous sequence-to-function relationships in this metagenome. In short, the identified thermostable laccase genes in this work could expand range of lignin biocatalysts and contribute to build an efficient lignin biorefinery.