土传真菌病害拮抗菌的筛选及其生防效果研究

为了获得对主要粮食作物水稻、小麦和经济作物大豆常见土传病害具有防治效果的生防菌,本研究从土壤中筛选到一株对所选6种病原真菌均有较好拮抗效果的菌株。基于形态学、生理生化特性及16S rDNA序列分析进行菌种鉴定,利用菌丝生长速率法对其无菌滤液和挥发性气体的抑菌效果进行验证,同时研究了其无菌滤液的热稳定性、酸碱稳定性和对蛋白酶K的稳定性。结果表明:本研究筛选到一株贝莱斯芽孢杆菌Bacillus velezensis CX-2,其无菌滤液对6种病原真菌的抑菌率在71%~95%之间,对小麦纹枯病菌、小麦全蚀病菌的抑菌率分别高达90.13%、94.34%;挥发性气体对6种病原菌的抑菌率在45%~80%之间;无菌滤液中的抗菌活性物质具有较强的热稳定性和对蛋白酶K的稳定性;无菌滤液pH在5~9之间时具有稳定的抑菌活性。该菌株可作为作物土传真菌病害生防菌剂较为理想的功能菌株。

Screening of antagonistic bacteria against soil-borne pathogenic fungi and evaluation of their biocontrol effects

In order to obtain the biocontrol bacteria against the common soil-borne diseases of rice,wheat and soybean,a strain with good antagonistic effect against six kinds of pathogenic fungi was screened from the soil.Then,the strain was identified based on morphological,physiological and biochemical characteristics and 16S rDNA sequence analysis.The antibacterial effects of the sterile filtrate and volatile gas were verified,and the inhibitory effects of the sterile fermentation broth under different conditions of temperatures,pH and protease treatment were also investigated.The results showed that the strain was identified as Bacillus velezensis.The inhibition rate of sterile fermentation broth against the selected six pathogenic fungi was 71%~95%,and the inhibition rate against Rhizoctonia cerealis and Gaeumannomyces graminis var.tritici was as high as 90.13%and 94.34%,respectively.The antibacterial rate of volatile gases against 6 pathogens was 45%~80%.The antibacterial active substance in sterile fermentation broth had excellent thermal stability and good tolerance to proteinase K.In addition,the sterile fermentation broth had a stable antibacterial activity when the pH value was between 5 and 9.As a result,the strain CX-2 could be used as a promising biological control candidate for the soil-borne diseases.