The button mushroom, Agaricus bisporus, is one of the major economical crops cultivated in Korea. This mushroom showed the 5th production to 11,493 M/T in 2014. This study examined changes in decomposition-related enzyme activity secreted by the microorganisms isolated from button mushroom composts. Among the isolated microorganisms, bacterial strains CY-36 were the most dominant and had the highest enzyme activities. 16S rDNA sequencing analysis showed 99% similarity of CY-36 to Bacillus amyloliquefaciens. To define the optimum conditions for the mass production of CY-36, we have investigated optimum culture conditions and effects of various nutrient source on the bacterial growth. The optimum initial pH and temperature were determined as pH 5.0~8.0 and 30°C, respectively. The optimal culture medium for the growth was determined as follows: 2.0% dextrin, 1.0% yest extract, 0.5% NaNO3, 3 mM MgSO4, and 0.6% valine. Enzymatic activities of CMCase and PGase secreted by CY-36 were the most prominent and CMCase activity were optimal at 40°C and pH 7.0, and PGase activity were 50°C and pH 6.0. The activity of CMCase was rapidly decreased at more than 4°C and pH 5.0, and the activity of PGase was rapidly decreased at more than 30°C but didn’t affect as pH change. Accordingly, Bacillus amyloliquefaciens CY-36 was potentially useful on the fermentation stimulation and softening of rice straw in the process of fermentation for mushroom cultivation.

This study examined changes in decomposition-related enzyme activity secreted by the microorganisms isolated from button mushroom composts. Among the isolated microorganisms, bacterial strains CY-24 were the most dominant and had the highest enzyme activities. 16S rDNA sequencing analysis showed 97% similarity of CY-24 to Bacillus licheniformis. To define the optimum conditions for the mass production of CY-24, we have investigated optimum culture conditions and effects of various nutrient source on the bacterial growth. The optimum initial pH and temperature were determined as pH 6.0 and 30°C, respectively. The optimal culture medium for the growth was determined as follows: 0.3% mannose, 1.5% yest extract, 0.8% (NH4)2HPO4, 2 mM MnSO4, and 0.5% asparatic acid. Enzymatic activities of CMCase and PGase secreted by CY-24 were the most prominent and CMCase activity were optimal at 50~60°C and pH 6.0, and PGase activity were 60°C and pH 6.0. The activity of CMCase was inhibited by metal ions including Ca+ and Cu+, while the activity of PGase didn’t affect. The activity of CMCase was rapidly decreased at more than 30°C and pH 7.0, and the activity of PGase didn’t affect as temperature change but was rapidly decreased at more than pH 5.0. Accordingly, This strain was potentially useful on the fermentation stimulation and softening of rice straw in the process of fermentation for mushroom cultivation.

This study analyzed population density changes and taxonomic characteristics of various microorganisms, which play important roles in culture medium fermentation of Agaricus bisporus and examined changes in decompositionrelated enzyme activity secreted by these microorganisms. Various microorganisms such as thermophilic bacteria, actinomycetes, fluorescent pseudomonas spp. and filamentous bacteria are closely related to culture medium fermentation of Agaricus bisporus. The population density of these microorganisms changes and harmful bacteria disappear during thermophilic fermentation. During outdoor fermentation, Psychrobacter sp., Pseudomonas sp., Bacillus sp. and Pseudoxanthomonas sp. showed the highest percentage distribution in the different culture medium while Bacillus sp. and Psychrobacillus sp. were the most dominant after pasteurization. When analyzing the enzyme activity of microorganism during rice straw fermentation, cellulose enzymes become important at the early stage of fermentation. Increase in hemicellulose enzyme follows after decomposing carbon sources. The microorganisms that secretes these enzymes were distributed at the second and third turning stage of fermentation.