<i>Deferrisoma palaeochoriense</i> sp nov., a thermophilic, iron(III)-reducing bacterium from a shallow-water hydrothermal vent in the Mediterranean Sea

A novel thermophilic, anaerobic, mixotrophic bacterium, designated strain MAG-PB1(T), was isolated from a shallow-water hydrothermal vent system in Palaeochori Bay off the coast of the island of Milos, Greece. The cells were Gram-negative, rugose, short rods, approximately 1.0 mu m long and 0.5 mu m wide. Strain MAG-PB1(T) grew at 30-70 degrees C (optimum 60 degrees C), 0-50 g NaCl l(-1) (optimum 15-20 g l(-1)) and pH 5.5-8.0 (optimum pH 6.0). Generation time under optimal conditions was 2.5 h. Optimal growth occurred under chemolithoautotrophic conditions with H-2 as the energy source and CO2 as the carbon source. Fe(III), Mn(IV), arsenate and selenate were used as electron acceptors. Peptone, tryptone, Casamino acids, sucrose, yeast extract, D-fructose, alpha-D-glucose and (-)-D-arabinose also served as electron donors. No growth occurred in the presence of lactate or formate. The G+C content of the genomic DNA was 66.7 mol%. Phylogenetic analysis of the 16S rRNA gene sequence indicated that this organism is closely related to Deferrisoma camini, the first species of a recently described genus in the Deltaproteobacteria. Based on the 16S rRNA gene phylogenetic analysis and on physiological, biochemical and structural characteristics, the strain was found to represent a novel species, for which the name Deferrisoma palaeochoriense sp. nov. is proposed. The type strain is MAG-PB1(T) (=JCM 30394(T)=DSM 29363(T)).