Study and Application of Microbial Community in Biodegradation of Kitchen Waste Using High-Throughput Sequencing and Strain Isolation Techniques

Kitchen waste contains abundant starch, cellulose, lignin, and other organic compounds. This study investigated the microbial diversity of composite microbial communities capable of efficiently degrading kitchen waste, with a focus on the isolation of lignin-degrading strains. High-throughput sequencing on the Illumina MiSeq platform was utilized to analyze the diversity and community structure of bacteria and fungi in kitchen waste, enabling the identification of core microbiota. Approximately 60 strains, representing over 20 genera, were successfully isolated and identified using pure culture techniques. Comparative analysis of microbial diversity, based on high-throughput sequencing and traditional strain isolation methods, revealed that bacteria predominantly belonged to the phylum Firmicutes, while fungi were mainly classified into Ascomycota and Basidiomycota. These methods provided complementary insights into the composition and diversity of microbial communities. Among the culturable strains, three high-yield laccase-producing fungi—Schizophyllum commune, Alternaria alternata, and Coriolopsis trogii—were selected. The laccase genes Sc-lac and Aa-lac were synthesized and heterologously expressed in Pichia pastoris, resulting in laccase activities of 180 and 43 U L⁻¹ in the supernatant, respectively. The laccases, Sc-lac and Aa-lac, were applied to degrade lignin, achieving degradation rates of 26.92% and 11.54%, respectively. The optimal temperature and pH for both laccases were 60°C and pH 3–3.5. These findings provide valuable insights into community structure analysis via high-throughput sequencing and the laboratory selection of cultivable strains. Furthermore, the screening and application of these enzymes and microorganisms contribute to reducing environmental pollution and promoting a sustainable, eco-friendly environment.