Straw microorganisms with combined cellulolytic and chitinolytic activities drive decomposition of rice straw and antagonism against Rhizoctonia solani causing rice sheath blight

Decomposition of cellulose and chitin substrates plays an important role in ecosystem functions. The relationships between the microbial diversity and the ecosystem functions of decomposition and antagonistic processes were examined using rice straw. A microcosm was designed for investigating complexity in microbial interactions of 16 different microorganisms belonging to 6 different functional groups and were designated as generalists or specialists depending on the number of hydrolases produced. Multiple regression analysis showed that increasing number of isolates, the presence of three fungal and one bacterial isolate and two fungal isolates degraded significantly to the decomposition process of rice straw. Straw was decomposed by one fungus and one bacterium, three fungal and two bacterial isolates and the 16-isolates mixture were significantly inhibited growth of the phytopathogenic Rhizoctonia solani causing rice sheath blight on the decomposed straw.The growth of R. solani was reduced significantly by 62% - 93% compared to the non-inoculated controls. There was a negative correlation between rice straw weight loss and the growth of R. solani. It is suggested that the specific isolates may play an important role in ecosystem functions of decomposition and antagonistic processes.