关键词: 大白菜, 多粘类芽胞杆菌, 立枯丝核菌, 抑菌谱, 发酵, 防效

Abstract: In this study，a biocontrol bacterium ZF197 isolated from the Chinese cabbage rhizosphere soil samples had significant inhibitory effect on Rhizoctonia solani. The strain was identified based on biological characteristics，physiological and biochemical characteristics，and multilocus sequence analysis. To investigate the control potential of strain ZF197 on R. solani，the control effect of strain ZF197 on R. solani was studied via leaves in vitro and potted plants in greenhouse inoculation experiment，and colonization abilities of strain ZF197 on the root of Chinese cabbage was via root colonization experiment. The biological characters of strain ZF197 was studied by enzymatic test and antimicrobial spectrum tests. The antagonistic ability of ZF197 was tested by the sandwich method，and the optimum culture and fermentation time of ZF197 fermentation broth were determined. The results indicated that the strain ZF197 was identified as Paenibacillus polymyxa. The control efficacy of leaves in vitro and potted plants in greenhouse was 82.35% and 78.57%，respectively. In addition，the strain could colonize the root of Chinese cabbage in a stable way，and the colonizing amount tended to be stable at about 2.37 × 105 cfu ? g-1 after the 20 d treatment. The strain ZF197 could produce protease and cellulase during the metabolic process，and exhibited broad inhibitory spectrum against eight pathogenic fungi and six pathogenic bacteria. The results of fermentation experiments indicated that the best fermentation time of ZF197 strain was at 96 h and the inhibition rate was 58.58%. Meanwhile，the fermentation broth of cottonseed meal had the best inhibitory effect on R. solani.

Key words: Chinese cabbage, Paenibacillus polymyxa, Rhizoctonia solani, antimicrobial spectrum, fermentation, control efficacy