深海热液区超嗜热古菌Thermococcus sp. TVG2的培养分离与鉴定

Isolation and identification of hyperthermophilic archaeon Thermococcus sp. TVG2 from deep-sea hydrothermal vent

摘要:

【目的】培养分离大西洋脊热液区的超嗜热古菌，为进一步认识该生态系统中的物种及其特点奠定基础。【方法】将大西洋脊热液区海水样品用YTSV培养基富集培养，选取其中富集效果最佳的TVG2培养物用减绝稀释法分离纯化。对所分离菌株进行形态、生理生化特征等分析，并通过分子生物学手段对其进行初步鉴定。【结果】菌株TVG2属于超嗜热厌氧球菌，直径约1.0 μm；生长温度范围50?88 °C，最适生长温度82 °C；生长pH范围为5.0?9.0，最适生长pH值为6.5；生长NaCl浓度为1.0%?4.0% (质量体积比)，最适生长浓度为2.5%；元素硫可显著提高菌株TVG2的生物量，但非生长必需；丙酮酸钠能显著促进该菌株生长，但葡萄糖对其生长则有抑制作用。根据其形态特征、生理生化特性及16S rRNA基因序列分析，确定菌株TVG2属于热球菌属。【结论】用YTSV培养基从大西洋脊热液区样品中分离获得超嗜热厌氧菌株TVG2，并确定其为Thermococcus属成员，命名为Thermococcus sp. TVG2。

关键词:深海热液区，超嗜热厌氧古菌，16S rRNA，热球菌属

Abstract:

[Objective] The aim of the present study was to isolate and identify hyperthermophilic archaea around the hydrothermal vent on the Mid-Atlantic Ridge, and to establish a foundation for further understanding and characterization of the microbial species in this ecosystem. [Methods] The hydrothermal vent seawater samples were enriched with YTSV media and strain TVG2 was purified from the enrichment cultures by the means of dilution-to-extinction. Strain TVG2 was characterized using morphologic, physiologic and biochemical analysis and preliminarily identified through the molecular biological methods. [Results] Strain TVG2 was an obligate anaerobic hyperthermophilic archaeon. Cells were regular cocci with 1.0 μm in diameter. It grew optimally at 82 °C (range 50?88 °C), at pH 6.5 (range 5.0?9.0) and with NaCl of 2.5% (range 1.0%?4.0%, w/v). Element sulfur was not indispensable for strain TVG2, but notably promoted its growth. Sodium pyruvate could significantly facilitate the growth of strain TVG2, whereas glucose had the opposite effect. Based on the morphological, physiological and biochemical characteritics and the 16S rRNA gene sequence analysis, strain TVG2 was regarded as belonging to Thermococcus. [Conclusion] Hyperthermophilic archaeon strain TVG2 was isolated from Atlantic Ridge hydrothermal vent samples with the YTSV medium and it was a member of the genus Thermococcus.

Key words:deep-sea hydrothermal vent, hyperthermophilic anaerobic archaea, 16S rRNA, Thermococcus