中文摘要：

微生物制剂是以自然界中分离的有益菌为主体开发的产品,在健康、环保及农业生产上应用广泛。某农业微生物制剂在海南的热带农业生产中能显著增产和增强作物抗性,为了了解该微生物制剂的作用机制,本研究采用平板划线法对活性菌进行分离和纯化,对分离菌株进行生长、形态及显微观察,对16S rDNA进行序列PCR扩增、测序及生物信息学分析,鉴定活性菌的种属。结果表明,分离得到2个形态不同的细菌菌株,通过形态观察及16S rDNA序列的分子鉴定,发现这2个菌株与枯草芽孢杆菌（Bacillus subtilis）具有99.9%的同源性;2个菌株的16S rDNA序列的比较结果发现它们有7个碱基的差别,说明这2个菌株可能是不同的生理小种。

英文摘要：

Microbial agents are useful products made of beneficial bacteria that isolated from nature environment,and it was extensively applied to healthcare,environment protection and agricultural production.A microbial agent has significant effects on increasing yield and improving disease resistance for Hainan tropical agriculture.In order to discover the activity mechanism of this microbial agent,it was necessary to isolate and identify its active bacteria.In this research,the following methods were applied,including active bacteria isolating and purifying,growth observation,morphological and microscopic observation,PCR amplification of 16S rDNA,sequencing and bioinformatic analysis.The results showed that two bacterial strains with different morphological character were isolated,16S rDNA sequences were amplified and sequenced,bioinformatic analysis indicated that 16S rDNA sequences of the two strains had 99.9% identities with that of Bacillus subtilis.Moreover,the 16S rDNA sequences of the two strains were compared with each other,and 7 base differences were found,it indicated that the two strains were different physiological races of Bacillus subtilis.