Screening And Fermentation Medium Optimization Of Biocontrol Microbe To Phytophthra Melonis

This paper adopts the plate dilution method was isolated from soil to100strains of actinomycetes, through plate standoff and mycelial growth rate combination, screened from7strains of Actinomyces on cucumber Phytophthora antagonism, of which NO39strong antibacterial activity, the fermentation liquid diluted5times on cucumber Phytophthora mycelium growth inhibition rate reached80.4%. The strain could inhibit the growth of Phytophthora capsici, Colletotrichum gloeosprioides, Phytophthora nicotianae, Sclerotinia sclewtiorum and Magnaporthe oryzae with antibacterial rate55%-75%.Use of prokaryotic16S rDNA universal primer on NO39gene DNA was amplified by PCR, and sequencing. In the NCBI BLAST alignment, the results showed that NO39and Streptomyces species by sequence homology to reach as high as99%, according to morphology, culture characteristics and physiological and biochemical characteristics, preliminary judge its gorgeous yellow streptomycete (Streptomyces flaveus).Through single factor and orthogonal experiment design method of variable of the strain NO39fermentation conditions were studied, the results showed that:the best carbon source is the best nitrogen source is glucose, peptone, the optimal fermentation medium was20g glucose, peptone,11g2G CaCO3,2G NaCl, water1000m L,28℃, pH7. After optimization, the hyphal growth inhibition rate reached a maximum of86.5%, increase5.1%than that before optimization. The results for the use of NO39strains on cucumber disease biological control provides scientific basis.