一株海洋放线菌的鉴定及其促生作用机理

【背景】海洋放线菌BM-2是本实验室从连云港海域分离得到的一株具有抗菌和促生作用的优良菌株，具有良好的开发应用前景。【目的】明确海洋放线菌BM-2的分类地位，揭示该菌株的促生作用机理，为菌株的开发应用提供理论依据。【方法】通过形态观察、生理生化特性和16S rRNA基因序列分析，对海洋放线菌BM-2菌株进行种属鉴定；采用透明圈法、平板划线法测定BM-2菌株解磷、解钾作用、固氮作用和产植酸酶、1-氨基环丙烷-1-羧基(1-aminocyclopropane-1-carboxylate，ACC)脱氨酶的能力；运用沙尔科夫斯基反应(Salkowski法)和铬天青(chromeazurol S，CAS)法分别测定菌株产吲哚乙酸(indole acetic acid，IAA)和产铁载体的能力。【结果】培养特征、菌落形态观察及生理生化试验结果表明，BM-2菌株符合链霉菌属(Streptomyces)的特征，16S rRNA基因序列与GenBank中栗褐链霉菌(Streptomyces badius)的序列相似性为99.72%；BM-2菌株具有固氮和解有机磷活性，能够产生ACC脱氨酶、铁载体和IAA。【结论】BM-2菌株为栗褐连霉菌(Streptomyces badius)，固氮、解有机磷作用以及产生ACC脱氨酶、IAA可能是该菌株的促生作用机制。

Identification and growth promoting effect of a marine actinomycete

Background] A marine actinomycete strain BM-2 was isolated from coastal area of Lianyungang, Jiangsu province. It showed both antibacterial and growth-promoting effects, and had a good prospect of development and application. Objective] To clarify the taxonomic status of strain BM-2, reveal its growth-promoting mechanism and provide theoretical basis for its development and application. Methods] Morphological observation, physiological and biochemical characteristics, combined with 16S rRNA gene sequence analysis were used for the identification of strain BM-2. The phosphorus and potassium solubilities, nitrogen fixing ability and phytase and 1-aminocyclopropane-1-carboxylate (ACC) deaminase activities of strain BM-2 were determined by transparent circle method and plate marking method. The ability of obtained strain to produce indole acetic acid (IAA) and siderophore were measured by Salkowski method, chromeazurol S (CAS) method, respectively. Results] According to the culture characteristics, colony morphology and physiological and biochemical tests, the strain BM-2 showed a typical feature of Streptomyces. Sequence analysis indicated that the 16S rRNA gene sequence of strain BM-2 had 99.72% sequence homology with Streptomyces badius in GenBank. Strain BM-2 had both nitrogen fixation and organophosphate solubility capacities and had the ability to produce ACC deaminase, siderophore and IAA. Conclusion] Strain BM-2 was identified as Streptomyces badius. Nitrogen fixation, organophosphate solubilities, ACC deaminase production, siderophore and IAA were the possible mechanism of its growth-promoting effect.