Screening and Isolation of Microbes for Promoting Humification of Agricultural Organic Wastes

Agroecosystems play a crucial role in carbon sequestration and reducing atmospheric CO2 emissions by storing organic carbon in soil. Soil fertility and productivity are essential for global crop demands and depend on soil organic matter, particularly humic substances (HS). HS is crucial for soil health and carbon sequestration as it involves the carbon cycle, supplies nutrients for plants, and reduces the emission of pollutants through microbial processes for the enhancement of CO2 sequestration. Humification is a natural process of organic matter stabilization, playing a crucial role in maintaining soil organic content and carbon storage. Laccase is used to polymerize monomeric compounds such as phenols and their derivatives into highly polymerized HS. We screened five cellulose-degrading isolates, among which three strains demonstrate lignin-degrading capabilities. WSC-7 exhibited the highest laccase activity and showed a high similarity [99.51%] to Arthrobacter defluvii based on 16S rDNA analysis. Strain LiPK-078-5 in nutrient broth medium and WSC-7 in Difco Sporulation Medium exhibited optimal catalytic activity for catechol, indicating their efficiency for aromatic polymerization of soluble organic carbon. The addition of rice husk biochar with strains LiPK-078-5, WSC-6, and WSC-7 increased organic carbon content effectively. The synthesis of humic substances in soil through microbial processes increases soil carbon sequestration and reduces greenhouse gas emissions in the environment.