拮抗南方根结线虫PKS基因的筛选及活性评价

土壤环境中蕴藏着巨大的微生物资源,而99%的土壤微生物不能用传统的纯培养。本研究基于西藏米拉山高寒草甸土壤微生物宏基因组Fosmid文库,采用PCR方法从文库中筛选PKS基因,以南方根结线虫(Meloido-gyne incognita)为靶标测定其杀线活性,并验证温室盆栽防效。从Fosmid文库中筛选得到2个含PKS基因的克隆K99和K82。K99属于Ⅰ型PKS,K82属于杂合PKS/NRPS;K99发酵液、热处理发酵液浸泡南方根结线虫J2 12 h后,杀线活性为100%。温室盆栽防效结果表明,K99的发酵菌液对南方根结线虫的防效为89%。K99能产生一种外分泌有杀线活性的物质,其热稳定性好,具有重要的开发利用价值。

Screening for PKS gene from soil metagenomics library and identification of the actives against root knot nematodes

Microorganisms dominate the soil ecosystem, but their roles are unclear due to the limitations associated with the uncultivability of at least 99% of the microorganisms. Clones containing PKS KS domain were screened by PCR method from a soil Fosmid metagenomic library from Tibet Mila Mountain, and the actives of PKS clones against root knot nematodes were also identified according to control efficiency in plots in greenhouses. The results showed that two clones (K99 and K82) containing PKS were obtained, of which K99 was type Ⅰ PKS and K82 the hybrid PKS/NRPS. The control effects of crude zymotic fluid and heat treatment fermentation liquid of K99 clone on J2 of root knot nematode in 12 hours was 100%, and the control efficiency in plots in greenhouses to nematode was 89%. Clone K99 produced some active substances that could kill root knot nematode and had a property of thermal stability. Therefore it was well worth exploiting and utilizing.