Ten isolates each of two different bacterial species isolated from the surface of a smear-ripened cheese were found to exhibit many characteristics of the genus Corynebacterium. The isolates were Gram-positive, catalase-positive, non-spore-forming rods that did not undergo a rod/coccus transformation when grown on complex media. Chemotaxonomic investigation revealed that the strains belonged unambiguously to the genus Corynebacterium. Their cell walls contained arabinose, galactose and short-chain mycolic acids (C22 to C36) and their peptidoglycan contained meso-diaminopimelic acid. The G+C content of the DNA was 51-60 mol%. MK-9 (H2) was the principal menaquinone. The 16S rDNA sequences of four isolates of each bacterium were determined and aligned with those of other members of the coryneform group. Phylogenetic analysis showed that the strains represented two new sublines within the genus Corynebacterium; Corynebacterium variabile and Corynebacterium ammoniagenes were their nearest known phylogenetic neighbours. Corynebacterium variabile and Corynebacterium ammoniagenes showed the highest levels of sequence homology with the isolates; however, DNA-DNA hydridization studies indicated that the Corynebacterium strains isolated from the cheese smear did not belong to either Corynebacterium variabile or Corynebacterium ammoniagenes (26 and 46% chromosomal similarity, respectively). On the basis of the phylogenetic and phenotypic distinctiveness of the unknown isolates, it is proposed that the bacteria be classified as two new Corynebacterium species, for which the names Corynebacterium mooreparkense sp. nov. and Corynebacterium casei sp. nov. are proposed. Type strains have been deposited in culture collections as Corynebacterium mooreparkense LMG S-19265T (= NCIMB 30131T) and Corynebacterium casei LMG S-19264T (= NCIMB 30130T).


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