Sporosarcina contaminans sp. nov. and Sporosarcina thermotolerans sp. nov., two endospore-forming species

Abstract

The taxonomic positions of two Gram-positive, endospore-forming rods, strains CCUG 53915T and CCUG 53480T, isolated from an industrial clean-room floor and from a human blood sample, respectively, were studied. 16S rRNA gene sequence similarity studies revealed that both isolates clearly clustered with Sporosarcina species. Strain CCUG 53915T was most closely related to Sporosarcina koreensis and Sporosarcina soli, showing 99.4 and 99.2 % 16S rRNA gene sequence similarities to the type strains of these species, respectively. Strain CCUG 53480T showed the highest 16S rRNA gene sequence similarities to the type strains of S. koreensis (98.7 %) and Sporosarcina saromensis (98.6 %). Strains CCUG 53915T and CCUG 53480T had peptidoglycan type A4α l-Lys–d-Glu. The quinone systems of both strains were composed predominantly of menaquinone MK-7, with small amounts of MK-8. The polar lipid profiles of both strains consisted of phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine and three unidentified phospholipids. The fatty acid profiles, which comprise anteiso- and iso-branched fatty acids, supported affiliation of the two isolates to the genus Sporosarcina. The results of physiological and biochemical tests and DNA–DNA hybridization data allowed a clear phenotypic and genotypic differentiation of both strains from the most closely related Sporosarcina species. For this reason, it is proposed that strains CCUG 53915T (=DSM 22204T) and CCUG 53480T (=DSM 22203T) represent two novel species in the genus Sporosarcina, with the names Sporosarcina contaminans sp. nov. and Sporosarcina thermotolerans sp. nov., respectively.