榕树根际土壤广谱拮抗菌株的筛选、鉴定及特性

于江西省吉安市内一株明万历年间植下的古榕树下,采集根际土样并使用23种指示菌通过管碟法和菌丝生长速率法对土壤内放线菌进行拮抗筛选,最终得到一株传代稳定的广谱拮抗菌株AHF-20.根据对菌株的形态观察、生理生化特性以及分子生物学鉴定,将该拮抗菌株鉴定为链霉菌,并对该菌株的抑菌活性物质进行了研究.结果表明:链霉菌AHF-20的发酵产物对23种测试指示菌全部具有拮抗效果,且抑菌能力稳定性较好,对温度、光照、紫外线、酸碱都有一定的耐受性,于121 ℃下加热20 min后依然存在抑菌活性.根据活性物质的极性使用正丁醇萃取发酵产物,获得的正丁醇粗提物稀释至1 μg·mL^-1后,对大肠杆菌仍有抑制效果,可见具有较好的生防利用潜力和开发成新型微生物药物的可能性.

Screening,identification and characterization of a broad-spectrum antagonistic strain in banyan rhizosphere soil

Rhizosphere soil samples were collected from an ancient banyan tree grown in the Wanli period of Ming Dynasty in Ji’an City, Jiangxi Province. Twenty-three kinds of indicator bacteria were used to screen soil actinomycetes by cylinder-plate method and mycelium growth rate method. A broad-spectrum antagonistic strain AHF-20 with stable passage was obtained. According to the morphological observation, physiological and biochemical tests, and molecular biological identification, the antagonistic strain was identified as Streptomyces. We examined the antibacterial active substance of the strain. The results showed that the fermentation products of Streptomyces AHF-20 had antagonistic effects on all the 23 test indicator bacteria. The antibacterial ability was stable, tolerant to temperature, light, ultraviolet, acid and alkali. Antibacterial activity still existed after heating at 121 ℃ for 20 min. The fermentation product was extracted with n-butanol according to the polarity of the active substance. The obtained crude n-butanol extract was diluted to 1 μg·mL^-1, which still had inhibitory effect for Escherichia coli. The results indicated that it has well utilization potential for biocontrol and developing new microbial drug.