南海硇洲岛潮汐带栉江珧可培养细菌的系统发育多样性

Phylogenetic diversity of cultivable bacteria associated with Atrina pectinata collected from the tidal flat of Naozhou Island in the South China Sea

摘要:

【目的】研究南海硇洲岛潮汐带栉江珧(Atrina pectinata)样品相关可培养细菌的多样性。【方法】采用纯培养法和基于16S rRNA基因序列的系统发育分析法对样品中可培养细菌(含放线菌)的类群多样性、物种多样性和遗传多样性进行研究。【结果】用补充0–25% (质量体积比) NaCl的MA、MH和NA培养基从栉江珧样品中分离到125株细菌。在形态观察和部分生理生化实验结果的基础上去冗余，选取90个代表性菌株进行基于16S rRNA基因序列的系统发育多样性分析。结果表明，这90个分离菌株分属于3个大的系统发育类群(Gamma-proteobacteria、Firmicutes、Actinobacteria)、6个科、10个属，可分为33个物种。优势类群为厚壁菌门(Firmicutes) (56株，62.2%)和γ-变形杆菌亚门(Gamma-proteobacteria) (31株，34.5%)。大多数菌株与其系统发育关系最密切的已知物种的典型菌株之间存在一定的遗传差异(16S rRNA基因序列相似性为95.7%–99.9%)，其中有5株可能代表新的分类单元(Potential new taxa)。分析表明，菌株JSM 112024可能代表了盐单胞菌科(Halomonadaceae)的一个属一级新分类单元；菌株JSM 112019、JSM 114045、JSM 114058和JSM 114083可能分别代表盐弧菌属(Salinivibrio)、芽孢杆菌属(Bacillus)、盐单胞菌属(Halomonas)和枝芽孢菌属(Virgibacillus)的新物种。【结论】湛江硇洲岛潮汐带栉江珧中存在较为丰富的可培养细菌物种多样性和系统发育多样性，并潜藏着较多的新微生物类群(物种)。

Abstract:

[Objective] To understand the diversity of cultivable bacteria associated with Atrina pectinata collected from the tidal flat of Naozhou Island (20°52′–20°56′N, 110°33′–110°38′E) in the South China Sea. [Methods] Bacteria strains were isolated from homogenates of the sample by using the conventional culture-dependent method and then investigated by using phylogenetic analyses based on 16S rRNA gene sequence comparisons. [Results] We isolated 125 bacteria strains from the sample on MA (marine agar), MH (moderate halophilic medium agar) and NA (nutrient agar) supplemented with 0–25% (W/V) NaCl. Based on partial morphological, physiological and biochemical characteristics, out of them, 90 strains were selected and subjected to a molecular systematic study based on 16S rRNA gene sequences. The results showed that the 90 isolates were members of 10 genera (Marinobacter, Chromohalobacter, Halomonas, Salinivibrio, Vibrio, Bacillus, Halobacillus, Virgibacillus, Staphylococcus, Micrococcus) of 6 families (Alteromonadaceae, Halomonadaceae, Vibrionaceae, Bacillaceae, Staphylococcaceae, Micrococcaceae) in 3 phylogenetic groups (Gamma-proteobacteria, Firmicutes, Actinobacteria). The most abundant and diverse isolates were within the phylum Firmicutes (56 strains, 62.2%) and the subphylum Gamma-proteobacteria (31 strains, 34.5%). The results of phylogenetic analyses suggested that there were obvious genetic divergences between most isolates and their closestly related type strains (16S rRNA gene sequence similarities ranging from 95.7%–99.9%). The results also showed that, out of the 90 isolates, at least 5 JSM strains (112019, 112024, 114045, 114058, 114083) should represent potential new taxa. Strain JSM 112024 could represent a novel genus in the family Halomonadaceae, and strains JSM 112019, JSM 114045, JSM 114058 and JSM 114083 could represent four novel species with in 4 characterized genera Salinivibrio, Bacillus, Halomonas and Virgibacillus, respectively. [Conclusion] There are abundant bacterial species diversity and phylogenetic diversity in the Atrina pectinata.