CLASSIFICATION OF GROUP IK - 2 AND RELATED BACTERIA

Abstract

Eleven strains of group Ik - 2 and related bacteria were studied for their phenotypic characters, guanine plus cytosine content of their deoxyribonucleic acid and cellular lipid composition, in comparison with those of 41 strains of 5 Flavobacterium species and the type strain of Cytophaga johnsonae. The 11 strains were nonmotile, nonfermentative, Gram-negative, oxidase-positive rods. The GC content of DNA was 38.9 + 0.9 mole%. Numerical analysis of 92 phenotypic characters indicated that the cluster of the 11 strains was rather close to C. johnsonae but clearly differed from 3 other major clusters: Flavobacterium meningosepticum, Flavobacterium Ib and Flavobacterium odoratum / breve group. Major fatty acids of total extractable lipids of Ik - 2 Organisms were 13-methyltetradecanoic acid and 2-hydoxy 13- methyltetradecanoic acid. The cellular lipids of 11 strains contained sphingophospholipids which was so far not found in Flavobacterium sp. and C. johnsonae strains. The most abundant molecular species of ceramides of the sphingophospholipids was determined as being composed of branched chain C17 sphinganine and 2-hydroxy 13.- methyltetradecanoic acid, exclusively. Based on the results of numerical analysis and presence of this unique sphingophospholipid, we are going to propose the new name, Sphingobacterium gen. nov. and Sphingobacterium versatilis sp. nov. for the group of strains, including those previously called group Ik - 2, according to the International Code of Nomenclature of Bacteria. The strain KM 2138 will be designated as the type strain for Sphingobacterium versatilis sp. nov, type species of the genus. Strains of Flavobacterium sp. group Ib are regarded as confoming to a separate species.