深海热液生物共附生可培养硫氧化细菌的多样性及硫氧化特性

Diversity and sulfur oxidation characteristics of culturable sulfur-oxidizing bacteria associated with benthic organisms in deep-sea hydrothermal area

摘要:

【背景】深海热液环境中存在大量H₂S及含硫化合物，许多微生物与大型生物形成了紧密的共生体系，例如硫氧化细菌，它们利用其独特的代谢体系协助宿主更好地适应极端环境，但目前尚未对热液底栖生物共附生的硫氧化细菌进行培养鉴定和功能分析。【目的】了解深海热液生物共附生硫氧化细菌的种群特征和功能特征，筛选出深海热液生物共附生微生物中的硫氧化细菌，分析其多样性及硫氧化功能，探讨这类细菌与宿主生物的共生关系。【方法】采用3种含硫培养基(M1、SPG、SOB)对热液区生物组织样品中的硫氧化细菌进行富集培养和分离纯化；利用16S rRNA基因序列确定它们的分类地位并进行系统发育分析；采用碘量法对典型硫氧化细菌的硫氧化活性进行检测。【结果】从热液底栖生物的鳃中分离得到169株硫氧化细菌，分属于变形杆菌门(Proteobacteria)和放线菌门(Actinobacteria)，优势菌属为盐单胞菌属(Halomonas)，占比为73%。硫氧化活性检测结果表明，Thioclava nitratireducens M1-LQ-LJL-11、Qipengyuania vulgaris M1-TC-YB-4和Dietzia cercidiphylli M1-TC-01-YL-6对硫化物的氧化率较高，分别达到了70.4%、77.7%和69.8%。【结论】通过培养的方法从热液底栖生物中了解到可培养共附生硫氧化细菌主要以γ-变形杆菌纲(Gammaproteobacteria)为主，并且具有较高的硫氧化能力，可为宿主解毒热液环境中的H₂S发挥重要作用。

Abstract:

[Background] Microbes in deep-sea hydrothermal vents use the extensive H₂S and sulfides in the environment to form a close symbiotic relationship with macrofauna. For example, sulfur-oxidizing bacteria use their unique metabolic system to help their hosts better adapt to the extreme conditions in hydrothermal vents. However, there is still no study on the identification and functional analysis of these symbionts of vent fauna. [Objective] To investigate the diversity and sulfur oxidation characteristics of culturable sulfur-oxidizing bacteria in hydrothermal benthos, and explore the symbiosis between sulfur-oxidizing bacteria and their animal hosts. [Methods] We used three culture media (M1, SPG, SOB) to isolate sulfur-oxidizing bacteria associated with hydrothermal benthos from different areas in the deep-sea hydrothermal vents. 16S rRNA gene sequences were used for phylogenetic analysis. The iodometric method was used to measure the sulfur oxidation activity. [Results] In the experiment, we obtained 169 strains of sulfur-oxidizing bacteria, which belong to Actinobacteria and Proteobacteria. Among them, the genus Halomonas was dominant, accounting for 73%. Three isolates showed higher sulfur oxidation activities:Thioclava nitratireducens M1-LQ-LJL-11 (70.4%), Qipengyuania vulgaris M1-TC-YB-4 (77.7%), and Dietzia cercidiphylli M1-TC-01-YL-6 (69.8%). [Conclusion] The diversity of culturable sulfur-oxidizing bacteria in hydrothermal benthos was reported for the first time. It was found that Gammaproteobacteria was the dominant, which had high sulfur oxidation ability and could detoxificate H₂S for their hosts in the hydrothermal fluids.