Isolation, characterization, and survival strategies of Thermotoga sp. strain PD524, a hyperthermophile from a hot spring in Northern Thailand.

A hyperthermophilic Thermotoga sp. strain PD524 was isolated from a hot spring in Northern Thailand. Cells were long-curved rods (0.5-0.6 × 2.5-10 μm) surrounded by a typical outer membrane toga. Strain PD524 is aero-tolerant at 4 °C but is aero-sensitive at 80 °C. A heat resistant subpopulation was observed in late-stationary phase. Cells from late-stationary phase were revealed remarkably less sensitive to 0.001 % SDS treatment than cells from exponential phase. The temperature range for growth was 70-85 °C (opt. temp. 80 °C), pH range was 6-8.5 (opt. pH 7.5-8.0), and NaCl range of 0 to <10 g/L (opt. 0.5 g/L). Glucose, sucrose, maltose, fructose, xylose, mannose, arabinose, trehalose, starch, and cellobiose were utilized as growth substrates. Growth was inhibited by S(o). Growth yield was stimulated by SO 4 (=) but not by S2O 3 (=) and NO3 (-). Analysis of 16S rRNA gene sequence (KF164213) of strain PD524 revealed closest similarity (96 %) to Thermotoga maritima MSB8(T), T. neapolitana NES(T), T. petrophila RKU-1(T), and T. naphthophila RKU-10(T).