Isolation Of Rare Actinomycetes And The Agricultural Bioactivity Of Fermentation Products

In this thesis, with the selective isolation methods of rare actinomycetes, 409 strains , of which thirty-three strains were rare actinomycetes, had been isolated from soil, water, desert, sand and coal of seven provinces, such as Shannxi, Henan, Qinghai, Shandong, Anhui, and so on. The studies on agricultural activity of the fermentation products of actinomycetes had been carried out. The main results are as follows:The results of insecticidal and herbicidal activities of fermentaion products of 409 strains showed that they had no obvious activity against Mythimna separata(3th instar larvae) or Amaranthus retroflexus.The fungicidal activities of fermentation broth of 409 strains against several agricultural pathogenic fungi were studied indoors. By means of mycelium growth rate, two strains, named as A1,G1, exhibited various inhibition against fungi. The fermentation broth of strain A1 had an inhibition rate of 95.7% and 96.4% against Alternaria solani and Gibberella zeae respectively. On the other hand, the fermentation broth of strain G1 showed inhibition rate of 94.4% and 95.7% against Bipolaris sorokiniana and Monilia fructigena. The results of spore germination tests indicated that the fermentaion products of G1 had higher inhibition activity than strain A1, the EC50 against Exserohilum turcicum, Curvularia lunata, Alternaria alternata and Fusarium coeruleum were 15.81 mg/L, 48.45 mg/L, 17.73 mg/L, 10.17mg/L respectively. The results of pot tests showed that the fermentation broth of strain A1 exhibited higher efficacy than strain G1 against Erusiphe graminis, the protective and therapeutic efficacy were 87.85% and 81.19%.The antibacterial activity of fermentation broth of 409 actinomycetes against several pathogenic bacteria of Gram positive and Gram negative had been finished. Six rare actinomycetes just showed antibacterial activity against Bacillus. Subtilis, while strain A1 and G1 exhibited a certain degree antibacterial action to all. Fermentation broth of strain A1 had 24mm inhibition circle against B. Subtilis, and 17mm against Staphylococcus aureus. Also, the fermentation broth of strain G1 had 21mm and 20mm activity against Bacillus.cereus and Erwinia. carotovora respectively.Based on the phenotypic information, including the morphology, cultural characteristics, physiological and biochemical properties, classification of strain A1 and G1 was studied. They were primarily proposed as Streptomyces sp..