轮纹病菌拮抗性大豆根瘤内生菌的筛选、抗性和促生作用

从河南部分地区采集的大豆根瘤中分离276株内生细菌,采用平板对峙法进行初筛、复筛和内生菌发酵滤液抑菌活性测定,对拮抗性代表菌株进行大豆轮纹病菌菌丝抑制效果显微观察、菌体生理生化特性测试、16SrDNA测序、系统发育分析及抗盐碱性试验和接种试验。结果表明,17株初筛内生菌经复筛和发酵滤液抑菌活性测定,其中8株抑菌率达50%以上;受作用菌丝发生扭结、缠绕成环状,菌丝末端分枝增多、变细、透明,部分菌丝末端膨大、原生质浓缩、断裂,一些菌丝被内生菌形成生物薄膜包埋、逐渐消融。8株内生菌中5株(DD013、DD123、DD156、DD159、DD287)初步鉴定为芽孢杆菌属Bacillus,DD150为赖氨酸芽孢杆菌属Lysinibacillu、DD267为肠杆菌属Enterobacter,菌株DD303为苍白杆菌属Ochrobactrum。抗盐碱性生长曲线表明,菌株DD287对3%NaCl盐浓度具有一定抗性,在碱性环境(pH8)下能正常生长,随pH(9~11)增大,菌体生长量受影响。部分拮抗性菌株对大豆生长有促进作用。筛选拮抗性菌株对丰富生物防治菌种资源具有重要意义。

Screening,Resistance and Growth Promoting of Antagonistic Endophytic Bacteria Isolated from Root Nodules of Soybean against Ascochyta glycines

Two hundred and seventy-six endophytic bacteria isolated from soybean root nodules of different areas in Henan province were screened by confrontation culture and fermentation filtrate culture methods for strains with strong inhibitory effect on Ascochyta glycines Miura, and morphological changes of phytopathogen hyphae was examined by microscopy. Their phylogenetic relationship was determined by homology analysis of the 16S rDNA sequences of PCR products, physiological and biochemical tests and 16S rDNA sequence analysis. In addition, the salt and alkali resistance assay and inoculation tests were conducted for representative strain. The results showed that seventeen antagonistic strains were verified by secondary screening and inhibition activity of fermentation filtrate methods, and 8 stronger antagonistic strains showed more than 50% inhibitory effect. The inhibited phytopathogen hyphae became mutual distorted, wrapped into a ring, terminal hyphae became branch increase, thin, transparent, and partially expanded forming protoplasm concentration and fracture, some hyphae were embedded by forming biofilms, gradually melted. Five (DD013, DD123, DD156, DD159, DD287) of eight endophytes were preliminary identified as Bacillus, DD150 as Lysinibacillus, DD267 as Enterobacter, DD303 as Ochrobactrum, respectively. The results of salt and alkali resistance and growth curve of strain with stronger inhibition effect showed that DD287 has certain resistance to 3% salt concentration, and can normally grow under alkaline environment (pH8), while affected by increasing pH (9~11). Some antagonistic strains here promoting effect on soybean growth. For screened antagonistic strains, it is of great significance to rich biological control strain resources.