Thermotogae Research Articles

Isolation of Thermotoga spp. and Fervidobacterium spp., and Characterization of 16S rRNA Genes of Order Thermotogales: Unique Lineage of Hyperthermophiles Thriving in 3 Hot Springs in Thailand

Order Thermotogales comprise mostly strictly anaerobic thermophilic and hyperthermophilic bacteria which thrive in high temperature habitats throughout the world. In order to study diversity of hyperthermophiles in Thailand’s hot springs, culture dependent technique was performed at 80 oC. Pure cultures of 19 isolates obtained from 3 hot springs were characterized based on 16S rRNA genes of order Thermotogales. Twelve and 7 isolates were identified as deepest blanches within two clades formed by divergent encapsulated rod shaped bacteria belonging to Fervidobacterium and Thermotoga, respectively. Phylogenetic evidences suggest that the Thailand strains from both branches are possible candidates for two novel species. Closely related strains within both genera were identified regardless of their habitats and years of sample collection, implying that these native inhabitants found in Thailand’s hot springs might have evolved from a unique common ancestor. Because all isolates require extremely high temperatures for growth, these isolates are likely sources of genes encoding numerous thermostable enzymes.

Diversity of Hyperthermophililic Bacteria Belonging to order Thermotogales Thriving in Three Hot Springs in Thailand: Resources of Genes Encoding Thermostable Enzymes

Hyperthermophilic microorganisms belonging to order Thermotogales and thriving in high temperature habitats grow at temperatures above 70 to near 100 o C. In this study, 15 rod shaped bacteria with characteristic of terminal sac-like membrane were isolated from Pong Duet, Fang, and Jae Son hot springs. Differential biochemical properties of the isolates were characterized. Twelve isolates were detected utilizing carbohydrates in CT basal medium, but no growth was observed in the other three isolates. Keratin in native duck feather was degraded at 75-80 o C by 8 isolates. Based on morphology, physiology, and 16S rDNA sequences, 5 and 10 isolates belonging to morphological groups I and II were identified as Thermotoga species and Fervidobacterium species, respectively. The 16S rDNA type II PCR profile of the isolates FC2004, FC201, FC202, FA004 and JS602 distinguish themselves from previously reported known species belonging to Fervidobacterium . Results obtained from this study indicate that some Thailand’s isolates are distinct, and the geothermal spring ecosystems are rich in divergent hyperthermophiles which still remain to be explored. The hyperthermophilic isolates are crucial sources of numerous thermostable enzymes with potential to be applicable in the degradation of polymers in agricultural wastes such as starch, cellulose, and keratin. Key words: hot spring ; hyperthermophile; Thermotogales ; thermostable enzyme