PYRODICTIUM-ABYSSI SP-NOV REPRESENTS A NOVEL HETEROTROPHIC MARINE ARCHAEAL HYPERTHERMOPHILE GROWING AT 110-DEGREES-C

Novel hyperthermophilic heteroktrophic members of the Archaea domain were isolated from marine hot abyssal as well as from shallow vents off Mexico and Iceland, respectively. The isolates grew between 80 and 110-degrees-C with an optimum around 97-degrees-C. They fermented carbohydrates, proteins, cell homogenates, acetate and formate. Isovalerate, isobutyrate, butanol and CO2 were detected as end products. Growth was stimulated by H-2. In the presence of S-degree, H2S was formed. Cells were disk-shaped and appeared entrapped within networks of fibres. Based on DNA/DNA homology and 16 S rRNA partial sequences, the new isolates represent a new species of Pyrodictium, which we name Pyrodictium abyssi. Type strain is isolate AV2 (DSM 6158).