Identification and Bacteriostatic Activity Analysis of an Antifungal Bacillus velezensis lut-Y1
[Objective]The aim of this study was to investigate the growth characteristics and antibacterial activity of a strain of Bacillus velezensis lut-Y1 from Lycium barbarum L.,and provide a reference for the development and application of microecologics.[Method]The strain was identified by morphological observation and 16S rDNA gene sequencing.The growth curve,optimum pH,carbon source,nitrogen source and salt tolerance of the strain were measured.The antagonistic effects of the strain on Alternaria alternate,Bipolaris sorokiniana and Ascochyta leptospora were observed by plate confrontation method.The antibacterial activity of the fermentation broth against three kinds of pathogenic fungi was analyzed.[Result]The lut-Y1 strain grew well on LB,NA and PDA medium.The strain lut-Y1 was identified as Bacillus velezensis based on its morphology and 16S rDNA gene sequence characteristic.In LB liquid medium,lut-Y1 strain showed a retardation stage from 0 to 3 h,a logarithmic stage from 3 to 18 h,a stable stage from 18 to 62 h,and a decline stage after 62 h.The optimal pH was 7.0,the optimal carbon and nitrogen sources were sucrose and peptone,respectively,and the tolerance to NaCl was no more than 2.0 g/L.lut-Y1 strain had obvious antagonistis effect on Alternaria alternate,but had weak antagonistic effect on Bipolaris sorokiniana and Ascochyta leptospora.At the junction of the two bacteria in the standoff plate,the mycelium in the base of Alternaria alternate was thin and curved.The mycelium cell wall was destroyed and bulbous protrusions were found in the base of Bipolaris sorokiniana.When the fermentation broth was added by 25％,the growth circle diameter were decreased by 72.80％and 83.24％,respectively.[Conclusion]Bacillus velezensis lut-Y1 had good antibacterial activity,which could provide materials for the development of microecological preparations and biological pesticides with Bacillus as the main active ingredient.
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