식물병원균에 대한 항진균 활성을 갖는 유용미생물의 분리 및 배양학적 특성

초록

For the efficient production of sawdust-based compost, microorganisms with high enzymatic activity and antifungal potential were isolated from natural sources. Among them, strain SM1-8 exhibited rapid growth and distinct clear zones on agar plates containing skim milk, soluble starch, and carboxymethyl cellulose. Enzyme assays in liquid culture revealed protease, amylase, and cellulase activities of 36.6±1.3, 7.5±1.5, and 23.5±2.7 units/ml, respectively. The SM1-8 strain also demonstrated strong antifungal activity against major plant pathogens, including Colletotrichum gloeosporioides, Botrytis cinerea, Fusarium oxysporum, Phytophthora cactorum, and Sclerotinia sclerotiorum, and was therefore selected as a promising candidate strain. Morphological and biochemical characterization indicated that SM1-8 is a Gram-positive, spore-forming bacillus measuring approximately 0.8‒1.3× 2.1‒3.4 μm, with positive oxidase, catalase, and urease activities but negative for indole production. Based on Bergey’s Manual of Systematic and Determinative Bacteriology, the isolate was identified as belonging to the genus Bacillus. Optimization of the culture medium revealed that 2% soluble starch as the carbon source and 0.5% yeast extract as the nitrogen source were most effective, while the addition of KCl and K2HPO4 slightly enhanced growth. Growth was vigorous at 35‒45℃ and pH 6‒8, with optimal cultivation near pH 6.7 without further adjustment. These results suggest that the strain Bacillus sp. SM1‒8 has potential as an effective microbial resource for composting and plant disease control.

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