Cloning, expression, and characterization of DNA polymerase I from the hyperthermophilic archaea Thermococcus fumicolans

The DNA polymerase I gene of a newly described deep-sea hydrothermal vent Archaea species, Thermococcus fumicolans, from IFREMERS's collection of hyperthermophiles has been cloned in Escherichia coli. As in Thermococcus litoralis, the gene is split by two intervening sequences (IVS) encoding inteins inserted in sites A and C of family B DNA polymerases. The entire DNA polymerase gene, containing both inteins, was expressed at 30 degrees C in E. coli strain BL21(DE3)pLysS using the pARHS2 expression vector. The native polypeptide precursor of 170kDa was obtained, and intein splicing as well as ligation of the three exteins was observed in vitro after heat exposure. The recombinant enzyme was purified and some of its activities were characterized: polymerization, thermostability, exonuclease activities, and fidelity.

Pyrococcus glycovorans sp. nov., a hyperthermophilic archaeon isolated from the East Pacific Rise

A hyperthermophilic archaeon, strain AL585T, was isolated from a deep-sea hydrothermal vent located on the East Pacific Rise at latitude 13 degrees N and a depth of 2650 m. The isolate was a strictly anaerobic coccus with a mean cell diameter of 1 micron. The optimum temperature, pH and concentration of sea salt for growth were 95 degrees C, 7.5 and 30 g l-1. Under these conditions, the doubling time and cell yield were 0.5 h and 5 x 10(8) cells ml-1. Strain AL585T grew preferentially in media containing complex proteinaceous carbon sources, glucose and elemental sulfur. The G + C content of the DNA was 47 mol%. Sequencing of the 16S rDNA gene showed that strain AL585T belonged to the genus Pyrococcus and was probably a new species. This was confirmed by total DNA hybridization. Consequently, this strain is described as a new species, Pyrococcus glycovorans sp. nov.

Thermococcus hydrothermalis sp. nov., a new hyperthermophilic archaeon isolated from a deep-sea hydrothermal vent

An extremely thermophilic archaeon, strain AL662T, was isolated from a deep-sea hydrothermal vent located on the East Pacific Rise at a latitude of 21 degrees N. This strain is a strictly anaerobic coccus, and its cells range from 0.8 to 2 microns in diameter. The optimum temperature, pH, and Sea Salt concentration for growth are 85 degrees C, 6, and 20 to 40 g/liter, respectively. Strain AL662T grows preferentially on proteolysis products, on a mixture of 20 amino acids, and on maltose in the presence of elemental sulfur. The membrane lipids consist of di- and tetraether glycerol lipids. The DNA G+C content is 58 mol%. Sequencing of the 16S rRNA gene showed that strain AL662T belongs to the genus Thermococcus. On the basis of hybridization results, we propose that this strain should be placed in a new species, Thermococcus hydrothermalis.