This study was conducted to selection and investigate appropriate conditions for mass production of antagonistic microbes to control cobweb disease caused by Cladobotryum mycophilum. A grampositive bacterium was isolated from spent substrate of Agaricus bisporus and showed significant antagonistic activity against Cladobotryum mycophilum. The bacterium was identified as Bacillus altitudinis. based on the cultural, biochemical and physiological characteristics, and 16S rRNA sequence. The isolate is saprophytic, but not parasitic nor pathogenic to cultivated mushroom whereas it showed strong inhibitory effects against C. mycophilum cells in vitro. The control efficacy of B. altitudinis HC7 against cobweb disease of C. mycophilum was up to 78.2% on Agaricus bisporus. The suppressive bacterium may be useful for the development of biocontrol system. To define the appropriate conditions for the mass production of the Bacillus altitudinis HC7, we have investigated appropriate culture conditions and effects of various nutrient source on the bacterial growth. The appropriate initial pH and temperature were determined as pH 6.0 and 30oC, respectively. The appropriate concentration of medium elements for the growth of pathogen inhibitor bacterium(Bacillus altitudinis HC7) was determined as follows: 3.0% soluble startch, 10% soytone, 1.0% (NH4)2HPO4, 1.0 mmol KCl, and 0.5% L-asparagine.

Cladobotryum mycophilum is the causal agent of cobweb disease of commercial mushrooms. Symptoms were noticed as round, fleshy, yellowish brown lesions on mushroom caps and progressed when the parasitic fungus formed white cobweb circular colonies on dead or damaged pinheads, spread on the surface of the casing. Two gram-positive bacterium were isolated from mushroom media that markedly showed the antagonistic activity against C. mycophilum.. These isolates were identified as Bacillus altitudinis and Bacillus subtilis by analysis of the cultural, morphological and physiological characteristics, and analysis of the 16S rDNA. The isolated bacteria is saprophytic but not parasitic nor pathogenic to cultivation mushroom. The isolated bacteria cell was sufficient for inhibition in vitro for C. mycophilum. Control efficacy of browning disease of Bacillus altitudinis treatment was 78% on Agaricus bisporus. The optimal culture medium was determined as follows: 3% Soluble startch, 10% Soytone, 1% (NH4)2HPO4, 1 mmol KCl, and 0.5% L-asparagin at pH 6.0 at 30°C. Control efficacy of browning disease of Bacillus subtilis treatment was 71% on Agaricus bisporus. The optimal culture medium was determined as follows: 1.5% Xylose, 2% Soytone, 1% NH4H2PO4, 7 mmol CaCl2, and 0.5% Histidine at pH 6.0 at 25°C. Accordingly, the suppressive bacterium may be useful in future for the development of biocontrol system and the construction of genetically modified edible fungi resistant to the disease caused by C. mycophilum.

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. Several fungus are known as the causal agents of diseases of the cultivated button mushroom (Agaricus bisporus) and oyster mushroom (Pleurotus ostreatus). Cladobotryum mycophilum is the causal agent of cobweb disease of commercial mushrooms. Early symptoms were noticed as round, fleshy, yellowish brown lesions on mushroom caps. Late symptoms progressed when the parasitic fungus formed white cobweb circular colonies on dead or damaged pinheads, spread on the surface of the casing, and covered entirely fruiting bodies. A Gram-positive bacterium was isolated from mushroom media that markedly showed the antagonistic activity against Cladobotryum mycophilum, the most destructive pathogen of cultivated mushrooms. The HC57 strain was selected as antagonistic bacterium by inhibition zone method and it was identified as Bacillus subtilis by the cultural, morphological and physiological characteristics, and analysis of the 16S rDNA. The isolated bacterium is saprophytic but not parasitic nor pathogenic to cultivation mushroom. The isolated bacterium for Cladobotryum mycophilum cell, was sufficient for inhibition in vitro. Inoculation of the isolated bacterium prevents the development of bacterial disease in Cladobotryum mycophilum. Control efficacy of browning disease of strain HC57 treatment was 71% on Agaricus bisporus. The optimal culture medium for the antagonistic bacteria growth was determined as follows: 1.5% Xylose, 2% Soytone, 1% NH4H2PO4, 7 mmol CaCl2, and 0.5% Histidine at pH 6.0 at 25℃. The suppressive bacterium may be useful in future for the development of biocontrol system and the construction of genetically modified edible fungi resistant to the disease caused by Cladobotryum mycophilum.

The button mushroom, Agaricus bisporus, is one of the major economical crops cultivated in Korea. This mushroom showed the 5th production to 10,996 M/T in 2012. Several fungus are known as the causal agents of diseases of the cultivated button mushroom (Agaricus bisporus) and oyster mushroom (Pleurotus ostreatus). Cladobotryum mycophilum is the causal agent of cobweb disease of commercial mushrooms. Early symptoms were noticed as round, fleshy, yellowish brown lesions on mushroom caps. Late symptoms progressed when the parasitic fungus formed white cobweb circular colonies on dead or damaged pinheads, spread on the surface of the casing, and covered entirely fruiting bodies. A Gram-positive bacterium was isolated from mushroom media that markedly showed the antagonistic activity against Cladobotryum mycophilum, the most destructive pathogen of cultivated mushrooms. The HC7 strain was selected as antagonistic bacterium by inhibition zone method and it was identified as Bacillus altitudinis. by the cultural, morphological and physiological characteristics, and analysis of the 16S rDNA. The isolated bacterium is saprophytic but not parasitic nor pathogenic to cultivation mushroom. The isolated bacterium for Cladobotryum mycophilum cell, was sufficient for inhibition in vitro. Inoculation of the isolated bacterium prevents the development of bacterial disease in Cladobotryum mycophilum. Control efficacy of browning disease of strain HC7 treatment was 78% on Agaricus bisporus. The optimal culture medium for the antagonistic bacteria growth was determined as follows: 3% Soluble startch, 10% Soytone, 1% (NH4)2HPO4, 1 mmol KCl, and 0.5% L-asparagin at pH 6.0 at 30°C. The suppressive bacterium may be useful in future for the development of biocontrol system and the construction of genetically modified edible fungi resistant to the disease caused by Cladobotryum mycophilum.

Cobweb disease symptoms were observed in a mushroom farm in Buye, Korea during a disease survey in 2008-2011. Five isolates of Cladobotryum sp. were obtained from the infected caps and stipes. These isolates of Cladobotryum sp. were identified as C. mycophilum based on their morphological, cultural characteristics and analysis of the ITS sequences. Early symptoms were noticed as round, fleshy, yellowish brown lesions on mushroom caps. Late symptoms progressed when the parasitic fungus formed white cobweb circular colonies on dead or damaged pinheads, spread on the surface of the casing, and covered entirely fruiting bodies. Optimal temperature and pH for mycelial growth on MEA is 23℃ and 6.0. Microscopically the spores of the fungus are large and most 2~3 celled produced on vertically branched conidiophores. Mushroom caps turned dark brown and shrunk due to soft rot. Testing of sensitivity to selected fungicides showed that isolate was highly resistance to Mancozeb and Thiophanate-methyl, moderately sensitivity to Iprodione, and highly sensitivity to Benomyl, Prochloraz-Mn and Carbendazim.