盐地碱蓬内生中度嗜盐菌的分离与系统发育多样性分析

Phylogenetic Diversity of Endophytic Moderately Halophilic Bacteria Isolated from Suaeda salsa L.

摘要:

为了解东营滨海盐地碱蓬植株内生中度嗜盐菌的多样性, 采用传统分离鉴定技术和基于 16S rRNA 序列分析对样品中可培养细菌的多样性进行研究。根据其生理生化特征、16S rRNA 序列测定和系统发育分析, 分离获得的15株内生菌可分为4个类群, 涉及 Halomonadaceae 科的 Chromohalobacter 属、Kushneria 属、Halomonas 属以及 Bacillaceae 科的 Bacillus 属。类群 I 中4菌株的16S rRNA 序列与 Chromohalobacter israelensis 的最高相似性为95%。类群 II 共7株菌, 归属于 Kushneria 属, 是碱蓬内生中度嗜盐菌中的优势类群。类群 III 菌株的16S rRNA 序列与一株尚无明确分类地位的 Gammaproteobacteria 亚门耐盐固氮细菌 Haererehalobacter sp. JG 11 的相似性为99%。类群 IV 中的芽孢杆菌的16S rRNA 序列与已知细菌的相似性为96%, 很可能代表了 Bacillus 属的新种。各种水解酶类的分析表明, 在分离的15株菌中有3株菌产蛋白酶, 14株产酯酶, 8株产DNA酶, 11株产半乳糖苷酶, 14株产脲酶。研究结果揭示, 盐地碱蓬中存在较为丰富的中度嗜盐菌多样性和系统发育多样性, 并且潜藏着较多的新的微生物类群。

Abstract:

The traditional isolation and identification method and analysis based on 16S rRNA sequences were used to investigate the phylogenetic diversity of endophytic moderately halophilic bacteria of Suaeda salsa L. in Dongying. According to physiological and biochemical characteristics, 16S rRNA sequences and phylogenetic analysis, 15 isolated endophytic bacterial strains were classified into four groups, belonging to genera Chromohalobacter, Kushneria, Halomonas or Bacillus separately. 16S rRNA sequences of 4 strains in Group I had the highest similarity to Chromohalobacter israelensis (95%). Group II which contained 7 strains of the genus Kushneria is the dominant group in Suaeda salsa L.. The strains in Group III bear the closest affiliation to Haererehalobacter sp. JG 11 (99%), which is not classified definitely. The only endospore-forming bacterium was classified into group IV. Its 16S rRNA sequence similarities with respect to the known Bacillus species were ≤ 96%, which was presumed to be potential novel species. Among these isolated strains, 3 strains produced proteinase; 14 strains produced esterase; 8 strains produced DNase; 11 strains produced galactosidase; 14 strains produced urease. The research results indicated that there was not only abundant phylogenetic diversity of moderately halophilic bacteria, but also some unknown bacteria groups existed in Suaeda salsa L..