Trichococcus shcherbakoviae subsp. psychrophilus subsp. nov., a psychrotolerant facultative anaerobe isolated from a cold spring

A psychrotolerant facultative anaerobe, strain SKBG(T), was isolated from the bottom sediments of the cold mineral spring Buxichen (Buryatia, Russia). Gram-positive non-motile cocci with a diameter of 1.75-2.5 mu m were observed singly or in long chains. Cells grew in the temperature range from-5-35 degrees C. Growth was observed within the pH range of 7.0-9.5, with the optimum growth at pH 7.6 and at a NaCl concentration from 0-1.0 % (optimum 0.1 % (w/v)). Strain SKBGT was a chemoorganoheterotroph that used sugars and some organic acids as substrates. The predominant fatty acids in cell walls were C-16:1 omega 9, C-18:1 omega 9, and C-16:0. The 16S rRNA gene sequence of strain SKBG(T) shared high similarity (>99 %) with those of the type strains of the genus Trichococcus. Digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) values between strain SKBG(T) and Trichococcus shcherbakoviae ArtT (=DSM 107162(T)=VKM B-3260(T)) were 70.1 and 95.4 %, respectively. The genomic DNA G+C content of strain SKBG(T) was 47.1 mol%. Compared with the type strain of T. shcherbakoviae, the new strain was characterized by a temperature optimum for growth (10 degrees C) significantly lower than that of T. shcherbakoviae DSM 107162(T) (20-30 degrees C). Based on phenotypic and genomic characteristics, the isolate SKBG(T) was classified as T. shcherbakoviae subsp. psychrophilus subsp. nov. The type strain is SKBG(T) (=VKM B- 3241(T)=JCM 33326(T)).