Basic Studies in Earlier Stage on Development of Streptomyces Qinlingensis Sp. NOV.
|School||Northwest University of Science and Technology|
|Keywords||agricultural antibiotics Streptomyces qinlingensis sp.nov. stability breeding fermentative condition optimization|
Streptomyces qinlingensis sp.nov. was isolated by pesticide institute of Northwest A&F University from the soil of qinling mountainous areas in shaanxi province, China. The fermentation products of Streptomyces qinlingensis sp.nov. exhibited strong fungicidal activity against pathogenic fungi and bacteria. This dissertation focused particularly on studies on the strain identification, the stability, bioactivity of fermentation broths, mutation breeding, protoplast fusion, fermentation condition optimization, the main results are as follows:The 16SrDNA sequence showed that the homology between strain No.24 and Streptomycesmaritimus was 99%. However,the morphological ,cultural,physiological and biochemical characteristics,the chemical components of the cell walls of the strain were different from those of the model strain. Strain No.24 produced simple yellow soluble pigment in Yeast extract agar, had LL-DAP and lactose in cell wall,could grow in the medium contained 5% NaCl. But Streptomyces maritimus produced no pigment in medium, had L-DAP in cell wall, and could not grow in 5% NaCl medium. So, strain No.24 was identified as representing a novel species of Streptomyces, which the name Streptomyces qinlingensis sp.nov. is proposed.The fungicidal activity of fermentation products of Streptomyces qinlingensis sp.nov.against pathogenic fungi and bacteria had been studied. The results of the inhibition rate of mycelium growth showed that the fermentation products had high inhibition rate against Exserohilum turcicum,Macrophoma kuwatsukai and Bipolaris sorokinana. and the EC50 values was 238.95 mg/l, 146.87 mg/l and 164.09 mg/l, respectively. The results of the inhibition of spore germination indicated that the fermentation products exhibited obvious inhibition rate against Exserohilum turcicum and Fusarium coeruleum, the EC50 values was 129.33mg/ml and 184.99mg/ml. In the bioassay of the fermentation product against Bacillus