相似穿孔线虫拮抗细菌的筛选及分子鉴定

【背景】相似穿孔线虫是一种重要的检疫性有害生物，其寄主范围广，危害具有毁灭性，已给我国农业生产造成潜在威胁。由于目前大多化学杀线剂毒性较高，筛选获得对相似穿孔线虫具有拮抗活性的微生物菌株对线虫防控具有重要意义。【方法】广泛从染病香蕉植株根际采集土壤样本，运用等比稀释涂布平板法分离菌株；采用摇瓶发酵法制备拮抗菌株上清液和发酵液。通过室内生物测定和盆栽试验，筛选出对相似穿孔线虫具有拮抗作用的细菌菌株，并通过16S rDNA的PCR扩增和序列分析，对拮抗菌株进行种类鉴定。【结果】获得5株对相似穿孔线虫具有较理想拮抗活性的细菌菌株。其中，菌株HD-86的作用效果最好，其发酵上清液处理24 h后的相似穿孔线虫死亡率达100%。盆栽试验表明，菌株HD-86发酵液处理42和70 d后对相似穿孔线虫的相对防效分别为77.34%和90.51%，均优于对照药剂阿维菌素。【结论与意义】菌株HD-86对相似穿孔线虫具有很强的拮抗作用，将其鉴定为洋葱伯克氏菌Burkholderia cepacia。本研究可为相似穿孔线虫生防制剂的研发和病害的防控提供依据。

Screening and molecular identification of antagonistic bacteria to Radopholus similis

【Background】Radopholus similis is an important quarantine pest that has wide host range and can cause a serious damage. It has become a potential threat to Chinese agricultural production. Because of the high toxicity of chemical nematicides, screening for and identifying potential bio-control microbes antagonist to nematodes is of important significance. 【Method】Soil samples were collected from the banana fields infected by R.similis, and the strains were isolated by the method of gradient dilution. The antagonistic bacterial supernatant and fermentation broth were obtained using shaking flask fermentation technique. Five isolates were screened against R.similis using toxicity tests and pot assay in greenhouse. The antagonistic bacteria were identified by amplification of 16S rDNA gene and sequence analysis. 【Result】Among five isolates, strain HD-86 had the best antagonistic effect with 100% mortality after 24 hours treatment of fermentation supernatant. In greenhouse trial, strain HD-86 showed the highest antagonistic activity against R.similis, compared to other strains and abamectin. HD-86′s performances 42 days and 70 days after fermented inoculation were 77.34% and 90.51% respectively. 【Conclusion and significance】HD-86 has a strong antagonistic to R.similis. Based on 16S rDNA sequence analysis, it was identified as Burkholderia cepacia. The basic basis for the development of nematicide and control of R.similis are provided in this paper.