Identification and growth promoting effect of a marine actinomycete

Abstract:

[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.