Screening Of Biocontrol Bacteria And Their Performce Against Rice Blast

Rice blast, caused by Magnaporthe oryzae, is a disaster fungus disease. In order to screen the antimicrobial microorganism resources against the disease effectively, the main biological characteristics of the antagonistic bacteria strains isolated from rice healthy plants inside diseased hills of the susceptible cultivar, Xiangzaoxian 24, as single cropping rice, in mountainous area of Taojiang, Hunan, in 2014. And the biological properties, the antagonistic activities against the M. oryzae and controlling the disease effciencies in the greenhouse were studed.1. Screening and Identification of the antagonistic bacteria817 strains were isolated from rice healthy plants among diseased plants of the susceptible cultivar Xiangzaoxian 24, as single cropping rice, in mountainous area of Taojiang, Hunan, in 2014. The antagonistic effects of JN005?YN008 and JW006 were relative significant which their radiis of inhibition zone against M oryzae were 15.32 mm, 11.70mm and 8.06mm, respectively. Based on the morphological, physiological, biochemical characteristics and the 16S rDNA phylogeny, the three strains, JN005? YN008 and JW006, were identified as Bacillus subtilis, Chryseobacterium indologenes and Salmonella, respectively.2. The antimicrobial spectrum of the above three srtainsThe antimicrobial spectrum of JN005, YN008 and JW006 against 5 kinds of plant pathogenic fungi,4 kinds of plant pathogenic bacteria, Escherichia coli and Staphylococcus aureus, were tested. And JN005 presented highly inhibitory activity to Fusarium graminearum and Ustilaginoidea virens, which inhibition ratio for the two fungi were 70.1% and 73.6%, respectively. However, YN008 and JW006 strains is relatively narrow antimicrobial spectrum.3. Optimization of fermentation conditions and efficacy of JN005 on rice blastThe medium component and conditions of fermentation were optimized by the orthogonal experiments, which its best culture conditions were glucose (15 g/L), soybean powder (15 g/L), and MgSO4 (2g/L) under the condition of 32?,180 rpm for 3 days. The efficiencies of the fermentation product and only living bacteria of strain JN005 on rice blast were tested by artificially inoculation in greenhouse, and the fermentation product showed both protective and curative activities, and while the spraying concentration was up to 20%, the efficiency of the fermentation product on rice blast was more than 85%; while the concentration of the living bacteria was more than 5.5×107 cfu/mL, the its efficiency was superior to isoprothiolane 40% EC.The study provided kinds of practical basis for riching the biological control resource against rice blast, and also provided technical basis for the industrial production of bio-control agents.