Planifilum composti sp. nov., a thermophile isolated from compost.

Two thermophilic bacteria, designated strains P8(T) and P12, were isolated from compost in Korea. The isolates grew aerobically from 50 to 75 °C (optimum at 55 °C) and at pH 4.0-9.0 (optimum pH 6.5). Aerial mycelia were not observed. Single spores were produced along the substrate hypha. The predominant menaquinone was MK-7. Major fatty acids were iso-C17 : 0, iso-C15 : 0 and iso-C16 : 0. The cell wall contained meso-diaminopimelic acid and the polar lipids were phosphatidylethanolamine, an aminophospholipid and sphingoglycolipid. The DNA G+C contents were 55.9-56.5 mol%. Phylogenetic analyses based on 16S rRNA gene sequences indicated that strains P8(T) and P12 belonged to the genus Planifilum in the family Thermoactinomycetaceae with sequence similarities of 96.1-97.2 %. Levels of DNA-DNA relatedness between strain P8(T) and the type strains of recognized species of the genus Planifilum ranged from 28.9 to 38.2 %. On the basis of data from the present polyphasic study, strains P8(T) and P12 are considered to represent a novel species of the genus Planifilum, for which the name Planifilum composti sp. nov. is proposed. The type strain is P8(T) ( = KACC 16581(T) = NBRC 108858(T)).