Planifilum fimeticola gen. nov., sp. nov. and Planifilum fulgidum sp. nov., novel members of the family ‘Thermoactinomycetaceae’ isolated from compost

Abstract

Four thermophilic, Gram-positive strains, designated H0165T, 500275T, C0170 and 700375, were isolated from a composting process in Japan. The isolates grew aerobically at about 65 °C on a solid medium with formation of substrate mycelia; spores were produced singly along the mycelia. These morphological characters resembled those of some type strains of species belonging to the family ‘Thermoactinomycetaceae’, except that aerial mycelia were not formed. Phylogenetic analyses based on 16S rRNA gene sequences indicated that the closest related species to the isolates were members of the family ‘Thermoactinomycetaceae’, but that the isolates formed an independent phylogenetic lineage. Some chemotaxonomic characters of the isolates, such as DNA G+C contents of 58·7–60·3 mol%, MK-7 as the major menaquinone and cellular fatty acid profiles, differed from those of members of the family ‘Thermoactinomycetaceae’. DNA–DNA hybridization showed that the isolates could be divided into two genomic groups, strain H0165T and the other three strains. These results indicated that the four isolates should be classified into two species of a novel genus in the family ‘Thermoactinomycetaceae’, for which the names Planifilum fimeticola gen. nov., sp. nov. (type strain H0165T=ATCC BAA-969T=JCM 12507T) and Planifilum fulgidum sp. nov. (type strain 500275T=ATCC BAA-970T=JCM 12508T) are proposed.