A novel actinomycete, strain OFN S31T, was isolated from a complex biofilm in the Altamira Cave, Spain. A polyphasic study was carried out to clarify the taxonomic position of this strain. Phylogenetic analysis with 16S rRNA gene sequences of representatives of the genera Corynebacterium, Dietzia, Gordonia, Millisia, Mycobacterium, Nocardia, Rhodococcus, Segniliparus, Skermania, Tsukamurella and Williamsia indicated that strain OFN S31T formed a distinct taxon in the 16S rRNA gene tree that was more closely associated with the Mycobacterium clade. The type strain of Mycobacterium fallax was the closest relative of strain OFN S31T (95.6 % similarity). The cell wall contained meso-diaminopimelic acid, arabinose and galactose, which are characteristic components of cell-wall chemotype IV of actinomycetes. The sugars of the peptidoglycan were acetylated. The polar lipid pattern was composed of phosphatidylinositol, phosphatidylglycerol, phosphatidylethanolamine and diphosphatidylglycerol. Strain OFN S31T is characterized by the absence of mycelium and mycolic acids. Strain OFN S31T had MK-8 as the major menaquinone. The DNA G+C content was 49.3 mol%, the lowest found among all taxa included in the suborder Corynebacterineae. Based on morphological, chemotaxonomic, phenotypic and genetic characteristics, strain OFN S31T is considered to represent a novel species of a new genus, for which the name Hoyosella altamirensis gen. nov., sp. nov. is proposed. The type strain of Hoyosella altamirensis is strain OFN S31T (=CIP 109864T =DSM 45258T). © 2009 IUMS.

This work was supported by the Centre National de la Recherche Scientifique (CNRS). The authors acknowledge funding from the Spanish Ministry of Culture for the microbiological study of Altamira Cave and from the Spanish Ministry of Education and Science, project CGL2006-07424. The facilities provided by the Museum of Altamira are acknowledged.

6 páginas, 2 figuras, 2 tablas. Jurado, Valme et al.--

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