一株促生抗病的樱花内生细菌的分离、筛选和鉴定

【目的】解决樱属植物生产过程中根癌病的发生问题。【方法】采用组织分离法和稀释分离法分别从枝干和叶片中分离内生细菌;采用滤纸片法选拮抗菌,通过形态学、生理学和分子生物学法对筛选菌株进行种类鉴定;通过比色法测定筛选菌株的解有机磷的能力;以特定培养基测定菌株产IAA(anxin)的能力,通过测定OD₆₀₀值判断耐NaCl的能力。【结果】在樱花体内共分离到32株内生细菌,其中从枝条内分离到28株,从叶片内分离到4株。对32株内生细菌进行抑菌活性的筛选,有2株对根癌农杆菌(Agrobacterium tumefaciens)有明显的抑制作用。另对其中的1株细菌YH-20进行鉴定,鉴定结果为瓦雷兹芽孢杆菌(Bacillus velezensis)。菌株YH-20具有良好的解有机磷和无机磷作用,其在第7天的解无机磷的量为178.43 mg/L,在第7天解有机磷的量为76.50 mg/L;具有较高的分泌IAA的能力,在第7天IAA的生成量为9.174 μg/mL;可在含10% NaCl的培养基上正常生长。【结论】筛选获得的瓦雷兹芽孢杆菌YH-20菌株具有抗植物根癌病菌和解磷能力,是一株在林木根癌病的防治上有很好应用前景的菌株。

Isolation,screening and identification of an endophytic bacteria in Ceresas with resistance to Agrobacterium tumefaciens and phosphorus solubilizing ability

【Objective】 Solve the problem of cherry root-cancer in cherry plant production. 【Method】 Endophytic bacteria were isolated from the leaves and branches of cherry plants using dilution separation and tissue separation, respectively. Antagonistic bacteria against Agrobacterium tumefaciens were selected by the filter paper method; strains were identified by morphological, physiological and molecular biology methods. The ability of a strain to screen for organophosphate residues was determined by colorimetry. Additionally, the ability of a strain to produce IAA and to resist NaCl was determined using a specific medium and by measuring bacterial density at OD₆₀₀, respectively.【Result】 A total of 32 endophytic bacteria were isolated from cherry plants, 28 of them were isolated from the shoots and 4 from the leaves. All the 32 endophytic bacteria were screened for antibacterial activity and only two strains showed a significant inhibitory effect over Agrobacterium tumefaciens. One of these bacteria, strain YH-20, was identified as Bacillus velezensis. Strain YH-20 also showed that it was capable of solubilizing organic and inorganic phosphorus. The amount of inorganic and organic phosphorus dissolved after 7 days was 178.43 and 76.50 mg/L, respectively. Strain YH-20 also had the ability to secrete IAA; it produced 9.174 μg/mL IAA after 7 days of incubation. B. velezensis strain YH-20 can grow normally on a medium containing 10% NaCl. 【Conclusion】 Therefore, the endophyte, Bacillus velezensis YH-20, obtained through this screening, is an antagonist of A. tumefaciens that has the ability to dissolve phosphorus. Thus, it is a strain with good application prospects in the prevention and treatment of root cancer in the forest.