Psychromicrobium silvestre gen. nov., sp. nov., an actinobacterium isolated from alpine forest soils.

Abstract

Two Gram-stain-variable, non-motile, catalase-positive and cytochrome c oxidase-negative bacteria, designated AK20-18T and AM20-54, were isolated from forest soil samples collected in the Italian Alps. Growth occurred at a temperature range of 5-30 °C, at pH 6-9 and in the presence of 0-5 % (w/v) NaCl. The 16S rRNA gene sequence similarity between strains AK20-18T and AM20-54 was 100 %. Phylogenetic analysis based on 16S rRNA gene sequence showed that strain AK20-18T had highest 16S rRNA gene sequence similarity with the type strain of Arthrobacter psychrochitiniphilus (96.9 %). The cell-wall peptidoglycan structure of strain AK20-18T was of the type A3alpha l-Lys-l-Thr-l-Ala2 (A11.27). The whole-cell sugars were galactose, ribose and lesser amounts of mannose. The major respiratory quinone of the two strains was menaquinone 9(H2) [MK-9(H2)], whereas MK-10(H2) was a minor component. The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol and unknown glycolipids. The major cellular fatty acids were anteiso-C15 : 0, iso-C15 : 0, iso-C16 : 0 and anteiso-C17 : 0. The genomic DNA G+C content was 59.9 mol%. Combined data of phylogenetic, phenotypic and chemotaxonomic analyses demonstrated that strains AK20-18T and AM20-54 represent a novel genus and species, for which the name Psychromicrobium silvestre gen. nov., sp. nov. is proposed. The type strain of Psychromicrobium silvestregen. nov., sp. nov. is AK20-18T (=DSM 102047T=LMG 29369T).