Thermus islandicus sp. nov., a mixotrophic sulfur-oxidizing bacterium isolated from the Torfajokull geothermal area

Abstract

Strains PRI 2268 and PRI 3838 T were isolated from two separate hot springs in the Torfajokull geothermal area of South Iceland. The cells were non-motile rods, approximately 0.3 mm in width and 1.5-2.5 mm in length. Electron microscopy revealed a Gram-negative cell-wall structure. The strains grew at 45-79 6C (optimum, 65 6C) and pH 5.5-10.5 (optimum, pH 6.0-7.0). 16S rRNA gene sequence analysis indicated that they formed a separate branch within the genus Thermus with 'Thermus kawarayensis' KW11 as their closest cultured relative (96.5 % similarity). The gene sequence similarities of both new isolates to Thermus aquaticus YT-1 T and Thermus igniterrae RF-4 T were 96.1 % and 95.5 %, respectively. DNA-DNA relatedness between strain PRI 3838 T and 'T. kawarayensis' was 46.1 %. The DNA G+C content of strain PRI 3838 T was 69.0 mol%. The predominant menaquinones, pigmentation, fatty acid profiles and phospholipid profiles of the novel strains were similar to those of other members of the genus Thermus. However, the new strains could be differentiated from the type strains of all other species of the genus Thermus by their lack of catalase activity and their utilization of only a few carbon sources. Furthermore, the novel strains exhibited mixotrophic growth with sulfur oxidation. On the basis of 16S rRNA gene sequence comparisons, DNA-DNA hybridization and physiological and biochemical characteristics, the new isolates represent a novel species. Since the species appears to be ubiquitous in Icelandic hot springs, the name Thermus islandicus sp. nov. is proposed. The type strain is PRI 3838 T (5DSM 21543 T 5ATCC BAA-1677 T ).

Thermus composti sp. nov., isolated from oyster mushroom compost

“…Strain K-39 T showed the peptidoglycan type A3b L-Orn-Gly-Gly, also published for other members of the genus Thermus (Quintela et al, 1995;da Costa et al, 2006). The DNA G+C content of strain K-39 T was 71.3 mol%, which is the highest in the genus (Brock & Freeze, 1969;Oshima & Imahori, 1974;Hudson et al, 1987;Kristjánsson et al, 1994;Williams et al, 1995Williams et al, , 1996Chung et al, 2000;Bjornsdottir et al, 2009;Zhang et al, 2010).…”

“…Nine further species have been described (Bjornsdottir et al, 2009;Zhang et al, 2010), originating from natural and artificial thermal environments such as hydrothermal areas, hot water taps, self-heating compost piles and rock surfaces (da Costa et al, 2006). In a recent article, Vajna et al (2010) investigated the microbiota during oyster mushroom (Pleurotus ostreatus) substrate preparation.…”

“…Growth at different temperatures in water baths [40, 50, 60, 65, 70, 75, 80, 82 and 85 u C, modified Thermus 162 medium (DSMZ Medium 878), 1 week], NaCl tolerance [0.5, 1, 1.5, 2 % (w/v), 65 u C, R2A broth, 1 week] and pH tolerance (from pH 3-11 by steps of 1, R2A, 1 week) were determined. Thermus 162 medium was modified according to Bjornsdottir et al (2009) as follows: it contained EGTA instead of Titriplex I, 0.05 % NH 4 Cl and 0.4 % vitamin solution (10 mg of p-aminobenzoic acid, nicotinic acid, calcium pantothenate, thiamine, pyridoxine, biotin and cyano-cobalamine Abbreviations: GL, glycolipid; PL, phospholipid. …”

Thermus parvatiensis RLT sp. nov., Isolated from a Hot Water Spring, Located Atop the Himalayan Ranges at Manikaran, India

“…Catalase activity was tested by adding 3 % (v/v) hydrogen peroxide solution to colonies grown on polypeptone-yeast extract medium [25]. To determine the physiologically optimal conditions for growth, strain RL T was incubated in polypeptone-yeast extract broth for 2 days at various temperatures (28, 37, 45, 55, 60, 70, 80°C), pH (1.0-10.0 at increment of 1 pH units) and NaCl concentrations (w/v 0, 1, 2, 3, 4, 5, 6,7,8,9,10). Tests were carried out as described earlier [26].…”

“…Several species of the genus Thermus have been isolated from natural and artificial thermal environments such as hydrothermal areas, hot water taps, self-heating compost piles and rock surfaces [2]. At the time of writing there were thirteen published species belonging to this genus including T. aquaticus [1], T. filiformis [3], T. scotoductus [4], T. thermophilus [5], T. brockianus [6], T. oshimai [7], T. igniterrae [8], T. antranikianii [8], T. kawarayensis [9], T. islandicus [10], T. arciformis [11], T. composti [12], T. caliditerrae [13].…”