<i>Pyrinomonas methylaliphatogenes</i> gen. nov., sp. nov., a novel group 4 thermophilic member of the phylum <i>Acidobacteria</i> from geothermal soils

An aerobic, thermophilic, moderately acidophilic non-spore-forming bacterium, strain K22T, wasisolated from geothermally heated soil at Mount Ngauruhoe, New Zealand. On the basis of 16SrRNA gene sequence similarity, K22T was shown to belong to subdivision 4 of the phylumAcidobacteria and to be most closely related to ‘Candidatus Chloracidobacterium thermophilum’(86 %) and Blastocatella fastidiosa (86 %). Cells stained Gram-negative and were catalase andoxidase-positive. The major fatty acids detected were iso-C15 : 0, iso-C17 : 0, iso-C19 : 0 and iso-C21 : 0 when standard lipid extraction protocols were employed. Analysis of the total cell lipid acidhydrolysate also detected membrane-spanning and ether lipids, which made up approximately40% of the total membrane composition. These lipids included dicarboxylic (iso-diabolic) acidand the glyceryl ether of alkyl analogues of iso-C15 : 0 and iso-diabolic acid. The G+C content ofthe genomic DNA was 59.6 mol% and the primary respiratory quinone was MK-8. Strain K22Tgrew at 50–69 6C with an optimum temperature of 65 6C and at pH 4.1–7.8 with an optimumgrowth pH of 6.5. NaCl tolerance was up to 1% (w/v). Cells displayed a chemoheterotrophic andobligately aerobic metabolism. Cells grew on nutrient broth, alginate, arabinose, Casamino acids,glucose, lactate, formate, mannose, sodium alginate, peptone, sucrose, tryptone, xanthan, xylan,xylose and yeast extract. Nitrogen sources included nitrate, ammonium, urea, yeast extract andCasamino acids, but not dinitrogen gas. The distinct phylogenetic position and the phenotypiccharacteristics separate strain K22T from all other members of the class Acidobacteria andindicate that it represents a novel species and genus, for which the name Pyrinomonasmethylaliphatogenes gen. nov., sp. nov. is proposed. The type strain of the type species is K22T(5DSM 25857T5ICMP 18710T)