Cellulolytic Microorganisms Selection from Organic Agricultural Soil and Their Ability to Degrade Rice Straw

Abstract

Rice straw management is a critical issue in agricultural systems due to the loss of soil organic matter, environmental impacts and air pollution, especially Phra Nakhon Si Ayutthaya Province, Thailand, where open-field rice straw burning remains one of the most significant agricultural pollution problems in the country. The use of cellulolytic microorganisms represents a promising approach to accelerate rice straw decomposition and enhance nutrient in soil. This study aimed to investigate the potential of cellulolytic microorganisms isolated from organic agricultural soil and their ability to degrade rice straw. Soil samples were collected from organic fields in Phra Nakhon Si Ayutthaya Province and analyzed for physicochemical properties and total microbial population. Cellulolytic microorganisms were isolated using Congo red assay on CMC agar, and high-efficiency isolates were characterized based on morphological and molecular identification. The selected isolates were evaluated for rice straw degradation under wet laboratory conditions. The results indicated that organic agricultural soil contained diverse microbial populations and more than 42 cellulolytic isolates were obtained. Moreover, isolate SeSt08 (Bacillus paralicheniformis) showed the highest cellulolytic activity with a clear zone diameter of 16.24 mm and showed effective rice straw degradation under laboratory conditions (68.04 – 73.80% weight loss). The potential of cellulolytic microorganisms from organic agricultural soil for development as biological agents for rice straw and agricultural residue management. The results of this study can be applied to reduce open-field burning, increase soil organic matter and support environmentally sustainable agricultural systems in the future.