Screening and identification of an antagonistic bacterium against banana fusarium wilt and its control effect in pot
[Objective]The study aimed to screen and identify a strain with antagonistic activity on the Fusarium oxysporum f.sp.cubense(E.F.Smith)Snyder et Hansen from banana rhizosphere soil,which would provide a theoretical basis for biological control of fusarium wilt of banana disease and strain resources.[Method]The microorganisms were isolated from banana fusarium wilt infected soil,silkworm and fer-menting algae by dilution plate separation method,and then the bacteria and fungi were isolated and purified by plate streak method and sin-gle spore separation method,respectively.With banana fusarium wilt subtropical race 4(Foc STR4)as the target bacteria,the screening test of antagonistic bacteria was conducted by plate confrontation method.The strains with the best inhibition effect were identified by gene se-quencing,and the physiological and biochemical indexes were determined.A pot experiment was conducted to control banana fusarium wilt with only Foc STR4 inoculation.[Result]An antagonistic bacterial strain named TU3-1 derived from diseased banana rhizosphere soil was shown to have effective inhibition for the Foc STR4,and antibacterial rate was 56.18％.It was found that TU3-1 was effective against 13 other plant pathogenic fungi such as Colletotrichum musa.Among them,it had the best inhibitory effect on C.musa,with an inhibition rate of 75.99％.The results of the potted plant experiment showed that,compared with the control group,the control effect of banana wilt dis-ease was 51.81％.Through gene sequencing,sequence comparison and physiological and biochemical characteristic experimental observa-tions,the TU3-1 strain was initially identified as Bacillus.It was a Gram-positive bacterium,anaerobic,with the ability to hydrolyze starch and cellulose to produce ammonia and protease.The optimum culture medium for TU3-1 strain was PDA medium,the optimum culture tem-perature was 30 ℃,and the optimum growth pH was 7.[Conclusion]Though screening and identification,a strain of antagonistic bacterium TU3-1,identified as B.velezensis,is screened and found to exhibit an inhibition rate of 56.18％against Foc STR4 and a control efficacy of 51.81％against banana wilt disease.It also inhibits 10 other plant pathogenic fungi and 3 plant pathogenic bacteria.TU3-1 exhibits broad-spectrum antibacterial activity,suggesting its potential as a valuable biocontrol bacterial germplasm resource for further development.
BananaFusarium oxysporum f.sp.cubense(E.F.Smith)Snyder et HansenAntagonist bacteriaBacillus velezensis
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