Studies On Identification And Biological Control Of The Major Pathogenic Organism Isolated From Oyster Mushroom In Nanning

Oyster mushroom is the most widely cultivated edible fungi in China. Oyster mushroom diseases occurred seriously in recent years, which caused serious economic losses, and hindered the development of the oyster mushroom industry in Guangxi. Pathogens, isolated from substrates, were identified on the base of morphological characteristic and a partial sequencing of 16S rDNA. At the same time, aggressiveness against the oyster mushroom and biological characteristic of pathogens were studied. On this basis, antagonistic microorganisms and plant extract were tested in order to study biological control mushroom diseases.The main results of this study are as follows:1. Fifty two pathogens were isolated from forty five substrates of oyster mushrooms. Based on morphological and molecular identification, thirty one pathogens were identified as Trichoderma harzianum, T.pleurotum, T.pleuroticola, T.longibrachiatum, and T.virens respectively. Six pathogens were identified as Neurospora; and other three kinds of pathogens have altogether fifteen strains. Four major cultivated oyster mushroom in Nanning were selected to test aggressiveness of the five kinds of Trichoderma. The result indicated that T.harzianum, T.pleurotum and T.virens showed strong aggressiveness against the four oyster mushroom.2. Effects of temperature and pH on growth of strain L3, L6, M11, M23, M15, M27 and M21 were tested. The results indicated that the optimum temperature and pH for mycelium growth of strain L3 and L6 were 35℃ and 5.0. The optimum temperature for mycelium growth of strain M11, M23, M15 and M21 was 30℃, while the strain M27 was 35℃. The optimum range of pH of 5 strains Trichoderma was 5.0-6.0.3.114 strains bacteria were isolated from substrates of oyster mushrooms, three of them showed strong inhibitory activities against pathogens (strain L3, L6, T.harzianum M11, T.pleurotum M23, T.pleuroticola M15) and weak inhibition effects against the four oyster mushroom. Antagonistic capabilities of the three antagonistic bacteria fermentation filtrates were tested. The results showed that three antagonistic bacteria fermentation filtrates had strong inhibition effects on the mycelia growth, sporulation and spore germination. When the bacterial fermentation filtrates concentration reached 40% in medium, antagonistic bacteria strains B44 and B106 have the best inhibitory activities while the bacterial fermentation filtrates concentration reached 50% in medium, antagonistic bacteria strains B72 has the best inhibitory activities. Antagonistic bacteria B44, B72 and B106 were identified as Bacillus subtilis based on morphology, physio-biochemical properties and a partial sequencing of 16S rDNA.4. Antimicrobial activity of sixteen Chinese Herbal Medicines were investigated. The results showed that Phytolacca acinosa has the strongest inhibition effects on mycelia growth of strain L3, L6, M11, M23, M15 and strong toxic against mushroom too. Mahonia bealei has strong inhibition effects on the mycelia growth of strain M11, M23 and M15, but the weak toxic activities against oyster mushroom. When the concentration of aqueous extract of Mahonia bealei in medium were 100mg/mL, inhibition rates were 73.72%、94.66%、96.23% against strain M11, M23 and M15 respectively while inhabitation rates were 28.97% and 20.83% against oyster mushroom Ping 558 and Xiuzhen 0811 respectively, which showed statistical difference.