沙棘根瘤内生细菌中抑菌促生菌株的筛选和鉴定

Screening and identification of antagonistic and plant-growth promoting endophytic bacteria from Seabuckthorn nodules

摘要:

【背景】植物内生细菌可产生具有抑菌和促生活性的物质，既能抑制植物病原菌对寄主植物的侵染，也能促进植物的生长。沙棘根瘤内生细菌是根瘤内除共生固氮的弗兰克氏菌外，与沙棘共生的一大类微生物。研究具有抑菌和促生活性的植物内生菌，可为微生物菌肥的研究提供理论基础。【目的】筛选具有优良抑菌和促生活性的沙棘根瘤内生细菌，初步研究其抑菌和促生活性，并对菌株进行鉴定。【方法】采用双层琼脂法、琼脂扩散法、双层平板对峙法、牛津杯法进行沙棘根瘤拮抗性内生细菌的筛选。选取抑菌活性较高的内生细菌，分别采用Salkowski比色法、Chrome Azurol S (CAS)平板检测法和钼锑抗比色法进行产吲哚乙酸、铁载体及溶磷能力的测定。采用发酵液灌根法测定沙棘根瘤内生细菌SR308对黄瓜促生作用的盆栽效果。通过形态和培养特征、生理生化试验及16S rRNA基因序列分析法对菌株TT201和SR308进行鉴定。【结果】从131株沙棘根瘤内生细菌中筛选出9株具有较强抑菌活性的内生细菌，其中菌株TT201抑菌性最佳、抑菌谱广；菌株SR308的促生活性最好，其发酵液对黄瓜的生长具有较强的促进作用。对具有较强抑菌和促生活性的菌株TT201和SR308进行鉴定的结果表明，菌株TT201为侧孢短芽孢杆菌(Brevibacillus laterosporus)，菌株SR308为蕈状芽孢杆菌(Bacillus mycoides)。【结论】获得2株具有优良抑菌和促生活性的沙棘根瘤内生细菌，为进一步开发微生物农药及菌肥提供了资源。

Abstract:

[Background] Endophytic bacteria can produce antagonistic and plant-growth promoting substances, which can not only inhibit host plants attacked by pathogens, but also promote the growth of plants. The endophytic bacteria from Seabuckthorn nodules are a kind of symbiotic microorganism. Studying endophytic bacteria with antagonistic and plant-growth promoting activity, which could be used as the basis of bacterial manure research. [Objective] To screen and identify efficient endophytic bacteria from Seabuckthorn nodules and study its activity of antagonistic and plant-growth promoting substances. [Methods] Antagonistic endophytes from Seabuckthorn nodules were screened by double agar layer piaque technique, agar diffusion assay, confrontation culture and oxford cup culture in vitro. The ability of indole acetic acid secretion were detected through the Salkowski colorimetric method, the production of siderphore were measured through the blue plate assay and phosphate solubilization were detected through Mo-Santispetrophotography method. The effects of growth promotion on cucumber seedlings were studied by using the fermentation broth of strain SR308. In addition, strain TT201 and SR308 were identified by morphological, culture, physiological and biochemical tests and 16S rRNA gene sequence analysis. [Results] Among 131 strains, 9 strains displayed the antagonistic and plant-growth promoting activity, especially strain TT201 displayed high antagonistic activity and broad antimicrobial spectrum; strain SR308 displayed high growth promoting activity. Pos tests showed that cucumber growth index treatment with SR308 fermentation broth were promoted significantly. Strain TT201 was identified as Brevibacillus laterosporus; strain SR308 was identified as Bacillus mycoides. [Conclusion] Two endophytic bacteria from Seabuckthorn nodules with antagonistic and plant-growth promoting activity are possible to be further developed as an excellent strain for microbial fertilizer and fungicide.