青稞散黑穗病拮抗菌LN-176的分离鉴定、发酵条件及发酵产物的研究

Isolation and identification of antagonistic bacterium LN-176 against Ustilago hordeum and analysis of the fermentation conditions and products

从西藏佩古错湖湖边的土壤中分离到一株对青稞散黑穗病菌具有较强抑制作用的细菌,经鉴定为多粘芽孢杆菌,命名为LN-176。该菌株对多种植物病原真菌、部分革兰氏阳性细菌及革兰氏阴性细菌有较好的拮抗作用。以10%的接种量将该菌接种到初始pH7.0的发酵培养基中,28℃旋转培养,发酵液在84h时抗菌活性达到最高,且具有较好的热稳定性和pH稳定性,对蛋白酶K有一定的耐受性。LN-176菌株的发酵液在260nm和280nm下进行吸光度测定,结果表明发酵液中蛋白质含量明显升高;发酵液经硫酸铵盐析后,取上清液和沉淀物分别做抗菌试验,发现沉淀物对青稞散黑穗病菌有拮抗活性而上清液无活性。

A bacterium isolated from a soil sample collected in lakefront of Peigucuo Lake in Tibet showed strong inhibitory activity to Ustilago hordeum. it was identified as Bacillus polymyxa, named LN-176 based on a preliminary taxonomic study. The strain also had strong antagonistic activity to several fungi causing plant diseases, Gram-positive bacteria and Gram-negative bacteria to some extent. The strain was inoculated to fermentive medium (pH 7.0) at the amount of 10 percent, cultured for 84 hours at 28℃ with shaking. Its antagonistic activity reached the highest level and high thermostability, pH stability and resistance to proteinase K were achieved. The culture filtrate of strain LN-176 was tested for light absorption at 260nm and 280nm, and the results showed that the protein content in the culture filtrate significantly increased. After ammonium sulphate precipitation, the supernatant and the precipitation were separated to testify their antagonistic activity, and it was found that the precipitation was inhibitory to Ustilago hordeum, but the supernatant not.