Tessaracoccus lapidicaptus sp. nov., an actinobacterium isolated from the deep subsurface of the Iberian pyrite belt

Abstract

A novel actinobacterium, designated IPBSL-7T, was isolated from a drilling core 297 m deep obtained from the Iberian Pyrite Belt. The strain was isolated anaerobically using nitrate as the electron acceptor. 16S rRNA gene sequence analysis revealed that it was related to Tessaracoccus flavescens SST-39T (95.7 % similarity), Tessaracoccus bendigoensis Ben 106T (95.7 %), Tessaracoccus lubricantis KSS-17SeT (95.6 %) and Tessaracoccus oleiagri SL014B-20A1T (95.0 %), while its similarity to any other member of the family Propionibacteriaceae was less than 94 %. Cells were non-motile, non-spore-forming, Gram-positive, oval to rod-shaped, and often appeared in pairs or small groups. The strain was facultatively anaerobic, oxidase-negative, catalase-positive and capable of reducing nitrate. Colonies were circular, convex, smooth and colourless. The organism could grow at between 15 and 40 °C, with an optimal growth at 37 °C. The pH range for growth was from pH 6 to 9, with pH 8 being the optimal value. Strain IPBSL-7T had peptidoglycan type A3-γ′, with ll-diaminopimelic acid as the diagnostic diamino-acid and glycine at position 1 of the peptide subunit. The dominant menaquinone was MK-9(H4) (93.8 %). The major cellular fatty acid was anteiso-C15 : 0 (55.0 %). The DNA G+C content was 70.3 mol%. On the basis of phenotypic and phylogenetic results, strain IPBSL-7T can be differentiated from previously described species of the genus Tessaracoccus and, therefore, represents a novel species, for which the name Tessaracoccus lapidicaptus sp. nov. is proposed. The type strain is IPBSL-7T ( = CECT 8385T = DSM 27266T).