Identification and Characterization of a Freshwater Pyrococcus sp. Strain PK 5017 and Identification of Pfu-Like IS Elements in Thermococcus sibiricus MM 739

Abstract

A strictly anaerobic, hyperthermophilic Pyrococcus sp. strain PK 5017 (PK 5017) was isolated from a freshwater hot spring in Thailand. Cells of strain PK 5017 are irregular cocci arranging singly and in pairs with a diameter range of 0.7-1.2 μm. Temperature, pH and NaCl concentration ranges for growth are o C (opt. temp. = 95-100 o C), pH 5-7.8 (opt. pH = 7.2) and 2.5-<40 g/l NaCl (opt. conc. = 24 g/l). Growths on the pancreatic digest of casein, yeast extract, peptone, meat extract, beef extract and skim milk (5 g/l ea.) occur in S o containing media. Growths on maltose, trehalose, starch and xylitol occur in S o -free media. No growth occurs on dextrose, sucrose, xylose, sorbitol, mannose and cellobiose. S o is not obligatory for growth, but stimulates growth. G+C content of genome is 42.5 mol%. DNA-DNA hybridization results reveal more similar genome sequence of strain PK 5017 to P. horikoshii than P. furiosus. Genome of strain PK 5017 contains multiple copies of the homologous IS-pfu of elements. Based on the biochemical characteristics and the presence of the homologous IS-pfus, strain PK 5017 is a close relative of P. furiosus. Two copies of IS-pfu homologs named "IS-pfu-Ts1" and "IS-pfu-Ts2" are identified in the complete genome sequence of Thermococcus sibiricus MM 739. Pyrococcus sp. strain PK 5017 = Pyrococcus sp. strain Pikanate 5017 = JCM17043 = ATCC BAA-2246.

Pyrococcus kukulkanii sp. nov., a hyperthermophilic, piezophilic archaeon isolated from a deep-sea hydrothermal vent

“…Only six species of the genus Pyrococcus have been described from shallow and deep-sea hydrothermal vents: Pyrococcus furiosus (Fiala & Stetter, 1986), Pyrococcus woesei (Zillig et al, 1987), Pyrococcus horikoshii (Gonz alez et al, 1998), 'Pyrococcus abyssi' (Erauso et al, 1993), Pyrococcus glycovorans (Barbier et al, 1999) and Pyrococcus yayanosii (Birrien et al, 2011). Two other members of the genus Pyrococcus were isolated from terrestrial environments: Pyrococcus strain HT3 from the 'El Biban' hot spring in Algeria (Kecha et al, 2007) and Pyrococcus strain Pikanate PK 5017 (Kanoksilapatham et al, 2012) from sediment collected near the Pong Duet Hot Spring in Thailand. By contrast to the hydrothermal vent of Mariner (Mid-Atlantic Ridge) where species of the genus Thermococcus are dominant, members of the genus Pyrococcus appear to be key players in the Guaymas Basin hydrothermal vents (Jannasch et al, 1992;Teske et al, 2009).…”