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

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.