广西北部湾海域表层海水细菌多样性及其潜在生物合成基因研究

Study on Biodiversity and Potential Biosynthetic Genes in Sur-face Seawater of Guangxi Beibu Gulf

本研究选取广西北部湾3处近海海域,以其表层海水作为研究对象进行细菌多样性分析,旨在挖掘潜在抗生素生物合成的菌株。选用传统稀释涂布法和基于16S rRNA基因序列的系统发育树分析海水中可培养细菌多样性,并对其基因组DNA进行抗生素生物合成基因聚酮合酶(PKS)基因、非核糖体肽合成酶(NRPS)基因及卤化酶(Halo)基因的扩增及检测。从海水中共分离到252株细菌,隶属于4门37属52种,变形菌门(Proteobacteria)是绝对优势类群(占总株数的68.25%),其后依次为放线菌门(Actinobacteria,17.06%)、厚壁菌门(Firmicutes,8.73%)和拟杆菌门(Bacteroidetes,5.95%)。在属水平,假单胞菌属(Pseudomonas)、链霉菌属(Streptomyces)、假交替单胞菌属(Pseudoalteromonas)和芽孢杆菌属(Bacillus)是主要的优势类群,共占总株数的38.89%。在4种分离培养基中,2216E培养基中分离细菌的数目与种类最多(83株,37种),其多样性指数均较高。分离获得的细菌新颖性突出,10株细菌与其近缘菌株16S rRNA基因的最高相似度低于98.65%,推测其为潜在的新种。此外,22株细菌的基因组DNA均扩增出至少1种次级代谢产物合成基因。综上所述,广西北部湾海域表层海水中可培养细菌多样性丰富,新颖性突出,可对含有抗生素生物合成基因的菌株进一步开展次级代谢产物的化学研究。

In this study,three characteristic sea areas in Beibu Gulf of Guangxi were selected,and the surface seawater was used as the research object for bacterial diversity analysis,aiming to explore the potential anti-biotic biosynthesis gene from these strains.The diversity of culturable bacteria in seawater was analyzed by traditional dilution coating method and phylogenetic analysis of 16S rRNA gene sequence.Polyketide syn-thase(PKS)gene,nonribosomal peptide synthetase(NRPS)gene and halogenase(Halo)gene were ampli-fied and detected.A total of 252 strains,belonging to 4 phyla,37 genera and 52 species,were isolated and i-dentified.Proteobacteria was the most dominant group(accounting for 68.25%of the total number of strains),followed by Actinobacteria(17.06%),Firmicutes(8.73%)and Bacteroidetes(5.95%).At the ge-nus level,Pseudomonas,Streptomyces,Pseudoalteromonas and Bacillus were the main dominant groups,ac-counting for 38.89%of the total number of strains.Among the four isolation mediums,the number and spe-cies of bacteria isolated in 2216E medium were the most(83 strains,37 species),and the diversity index was higher.The novelty of isolated bacteria was prominent,and the highest similarity of 16S rRNA gene between 10 strains of bacteria and their related strains was less than 98.65%,so they were speculated as potential new species.In addition,at least one secondary metabolite synthesis gene was amplified from genomic DNA of 22 strains of bacteria.In summary,the culturable bacteria in the surface seawater of Guangxi Beibu Gulf are rich in diversity and outstanding in novelty,and the strains containing antibiotic biosynthesis genes deserve fur-ther chemical research on secondary metabolites.