Paracoccus onubensis sp. nov., a novel alphaproteobacterium isolated from the wall of a show cave

A novel facultatively anaerobic, non-motile, Gram-stain-negative, non-endospore-forming alphaproteobacterium, strain 1011MAR3C25(T), was isolated from a white biofilm colonizing the walls of the Andalusian show cave Gruta de las Maravillas (Huelva, Spain). Strain 1011MAR3C25(T) grew at 8–42 °C (optimum, 20–30 °C), at pH 5.0–9.0 (optimum, pH 5.0–6.0) and in the presence of 0–12 % (w/v) NaCl (optimum 3–5 %). Cells were catalase- and oxidase-positive. The strain grew heterotrophically with various carbon sources and chemoautotrophically with thiosulfate under aerobic conditions. Results of phylogenetic analysis showed that strain 1011MAR3C25(T) was related to Paracoccus saliphilus DSM 18447(T) and Paracoccus alkanivorans LMG 30882(T) (97.90 % and 97.32 % 16S rRNA sequence identity values, respectively). The major respiratory quinone was ubiquinone Q-10 and the predominant fatty acid was C(18 : 1 )ω7c. The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylcholine, phosphatidylglycerol, an unidentified aminolipid, an unidentified glycolipid and an unidentified polar lipid. The DNA G+C content was 60.3 mol%. Based on a polyphasic taxonomic study it is proposed that strain 1011MAR3C25(T) (=CECT 9092(T)=LMG 29414(T)) represents a novel species of the genus Paracoccus , for which the name Paracoccus onubensis sp. nov. is proposed.