Isolation,Screening and the Optimization of Fermentation Conditions of Biocontrol Bacteria against Eleutherococcus senticosus Black Spot
[Objective]The biocontrol bacteria against Eleutherococcus senticosus black spot were isolated,screened and identified,and the fermentation conditions of bacteria were optimized.This study may provide a good source of biocontrol bacteria against E.senticosus black spot.[Method]The serial dilution method was used to isolate bacteria from healthy E.senticosus rhizosphere soil,and the plate confrontation method was used to screen strains with strong antagonistic effects on A.tenuissima,and the inhibitory effects on other 5 pathogenic fungi were measured.The taxonomic status of this strain was clarified based on morphological characteristics,physiological and biochemical characteristics and 16S rDNA gene sequencing.The culture medium components and fermentation conditions were optimized using single-factor experiments and orthogonal experiments.The effect of fermentation broth of this strain on the biocontrol efficiency against E.senticosus black spot was also studied.[Result]Total 419 strains of bacteria were isolated,among which the strain YZ-228 had the highest inhibitory rate of 67.38％against A.tenuissima,the inhibition rate of sterile filtrate against A.tenuissima was 64.32％.And strain YZ-228 had the inhibitory effects against Rhizoctonia solani,Fusarium solani,Alternaria panax,Cylindrocarpon destructans,and Fusarium oxysporum,with an inhibition rate of 62.80％-67.89％.Strain YZ-228 was identified as Bacillus cereus.Soluble starch and beef extract were the best carbon and nitrogen sources for YZ-228.Under the condition that the pH,temperature,inoculum,liquid volume and speed were 7.0,28℃,3％,50 mL/250 mL and 200 r/min,respectively,the bacterial solution fermented for 1 d had a good antagonistic effect on A.tenuissima,with an inhibition rate of 74.19％.It was 11.99％higher than that in beef extract-peptone-yeast extract medium(BPY).In addition,inoculation of the fermentation broth of strain YZ-228 significantly reduced the disease index of E.senticosus black spot,and its control effect was 59.15％.[Conclusion]B.cereus YZ-228 has good control effect on E.senticosus black spot and has the potential to be used as a biological control agent for E.senticosus black spot.
Eleutherococcus senticosusAlternaria tenuissimaBacillus cereusblack spotbiological control
万方数据
维普
