Thermococcus kodakarensis

A Microbial Biorealm page on the genus Thermococcus kodakarensis

Thermococcus kodakaraensis Image by F. Fukuri, Kyoto University

Classification

Higher order taxa

cellular organisms; Archaea; Euryarchaeota; Thermococci; Thermococcales; Thermococcaceae; Thermococcus

Genus

Thermococcus kodakarensis

NCBI: Taxonomy

Description and significance

Previously characterized as Pyrococcus sp., Thermococcus kodakarensis is a sulfur-reducing hyperthermophilic archaeon which typically inhabits marine hydrothermal vents and terrestrial hot sulfur springs. This organism and other hyperthermophiles are of great interest as they have evolved mechanisms for adaptation to extremely high temperature enviorenments. The prokaryote grows at an optimal temperature of 86C, between the ranges of 60-100C, and in a pH range of 5-9. Although this organism is a representation of simple life forms, it grows and thrives in temperatures up to the boiling point of water.(T. Imanaka et al) In the absence of sulfur, these heterotrophs ferment a variety of organic compounds, including amino acids, peptides, and sugars. Recent accumulation of 16sRNA sequences has indicated the organism belongs to the Thermococcus genus, and not to the originally hypothesized Pyrococcus genus.

Thermococcus kodakarensis was isolated from a solfatara (a volcanic area that releases only hot vapors and sulfurous gases into the environment) on Kodakara Island, Japan, and sequenced by the Kyoto University, Japan.(Morikawa M. et al) This organism produces commercially applicable thermostable DNA polymerases and enzymes that would be useful for such techniques as PCR.

Thermococcus kodakarensis belongs to the most commonly isolated hyperthermophilic organisms, Thermococcus sp. and are often isolated from marine hydrothermal vents and terrestrial hot sulfur springs. The genome of T. kodakarensis encodes several proteins found within genetic elements similar to those in Pyrococcus spp., implying mechanisms of horizontal gene transfer of mobile elements among the order Thermococcales.

Hyperthermophiles are microorganisms that can grow and survive at and above 100 C (the boiling point of water). (Prieur D. et al) These microorganisms were discover in 1982 by Stetter and are considered to be the most ancient form of life. (Adams MW et al) Most hyperthermophiles depend entirely on the reduction of elemental sulfur to hydrogen sulfur for significant growth, resulting in the hindrance of large-scale culture in conventional fermentation systems. (Lepage E et al) After Stetter's first isolation of hyperthermophiles, there have been approximately 20 different genera discovered and added to the class of microorganisms.

Genome structure

The Thermococcus kodakaraensis genome contains 2.09 Million base pairs (bp) and is predicted to have approximately 2357 genes. The chromosome has a circular topology and the GC content is estimated to be 38 mol%. Seven genes for probable transposases and four virus-related regions are found within the genome. (Fukui. T et al)

Cell structure and metabolism

Thermococcus kodakarensis have an irregular cocci (1-2 µm diameter) cell structure and are motile with several polar flagella. T. kodakarensis has a single ether lipid membrane. This strictly anaerobic(existing without oxygen) microorganism uses amino acids, peptides, pyruvate, and starch as its carbon and energy sources. Metabolic pathways of T. kodakarensis include gluconeogenesis and glycolysis and the products of metabolism are hydrogen and hydrogen sulfide gas.

Ecology

In addition, because Thermococcus kodakarensis is present in natural high-temperature environments, it plays a major role in the microbial ecology of hot-water ecosystems. Whithin the microbial communities that inhabit these hydrothermal environemtns, THermococcales have been frequently isolated from marine geothermal environments wiht 28 species currently described within the general Pyrococcus, THermococcus, and Paleococcus. (Prieur D. et al)

Application to Biotechnology

Does this organism produce any useful compounds or enzymes? What are they and how are they used?

Current Research

Enter summaries of the most recent research here--at least three required

Hyperthermophilic orgnanisms are nevertheless relatively easy to handle and grow in the laboratory, probably becuase they can resist ozygen exposure at room temperature. So they have become widely studied model microorganisms in various fields of investigation, such as adaptation to extreme temperature, molecular deciphering of DNA replication mechanisms in Archaea, Phylogeny and genome evolution, and the genes they carry could prove to be rrich and valuable sourcees of biotechnoligcally important products. (Prieur D.)