药用植物内生芽孢杆菌的多样性和系统发育研究

目的]了解药用植物内生芽孢杆菌的生物多样性.方法]采用数值分类、16S rDNA PCR RFLP、BOX-PCR指纹图谱和16S rDNA序列分析技术对分离于几种药用植物的内生芽孢杆菌和已知参比菌株进行表型、遗传多样性及系统发育研究.结果]供试菌株在数值分类聚类分析中在84%的相似水平上产生13个表观群.16S rDNAPCR-RFLP分析表明供试菌株表现出丰富的遗传多样性.BOX-PCR指纹图谱分析进一步证明药用植物的内生芽孢杆菌的基因组也具有多样性,聚群的结果与数值分类有较好一致性.用软件在Genbank中进行所得序列的同源性检索,并构建系统发育树.由16S rDNA序列分析可知,供试的代表菌株SCAU11与球形芽孢杆菌(Bacillus sphaericus)亲缘关系最近,SCAU78和SCAU25为枯草芽孢杆菌(Bacillus subtilis)的两个亚种,代表菌株SCAU39与巨大芽孢杆菌(Bacillus megaterium)的亲缘关系最近.结论]研究结果表明药用植物内生芽孢杆菌具有明显的表型和遗传多样性.

Phylogeny and diversity of endophytic Bacillus isolated from medicinal plants

Objective]The biodiversity of endophytic Bacillus isolated from Medicinal plants was studied. Methods] Endophytic bacillus isolated from medicinal plants and reference strains were characterized by numerical taxonomy, 16S rDNA PCR-RFLP, BOX-PCR fingerprints and 16S rDNA sequence to describe the phenotypic and genetic diversity and phylogeny. Results]The phenotypic characterization of these strains showed that most of these strains had high stress resistance. There were 13 clusters formed at 84% similarity by numerical taxonomy. The genetic diversity was highly revealed by 16S rDNA PCR-RFLP. The diversity of genomic level was described by BOX-PCR fingerprints. The results were correlated well with numerical analysis. Homology analysis was made by searching in Genbank with NCBI, and the phylogenetic tree was reconstructed. Sequence analysis of 16S rRNA gene showed that SCAU11 was highly related to B. sphaericus, SCAU78 and SCAU25 were identified as B. subtilis subspecies, SCAU39 was highly related to B. megaterium. Conclusion]Overall, the study results demonstrated a high phenotypic and phylogenetic diversity of endophytic Bacillus isolated from Medicinal plants.