Classification of three corynebacterial strains isolated from the Northern Bald Ibis (Geronticus eremita): proposal of Corynebacterium choanae sp. nov., Corynebacterium pseudopelargi sp. nov., and Corynebacterium gerontici sp. nov.

Three Gram-stain-positive, rod-to-coccoid-shaped, catalase-positive and non-motile bacterial strains isolated from the choanae of a Northern bald ibis, designated strains 200CHT, W8T and 812CHT, respectively, were subjected to comprehensive taxonomic characterization. The three strains were oxidase-negative. The 16S rRNA gene sequence of 200CHT showed highest similarities to Corynebacterium epidermidicanis 410T (96.7 %) followed by Corynebacterium argentoratense DSM 44202T, Corynebacterium ulcerans NCTC 7910T and Corynebacterium pseudotuberculosis CIP 102968T (each 96.3 %). Strains W8T and 812CHT both showed highest 16S rRNA gene sequence similarities to Corynebacterium pelargi 136/3T (98.0 and 99.9 %, respectively). Comparison of the partial housekeeping gene sequence of fusA showed higher sequence similarities of 812CHT to C. pelargi (95.8 %) than W8T (90.9 %) which was also confirmed by corresponding amino acid sequences. In both, fusA gene and corresponding protein sequence strain 200CHT showed low sequence similarities to C. epidermidicanis 410T(81.6 and 87.4 %, respectively). Strains 812CHT and W8T had 76.7 % ANI similarity to each other and 88.2 and 76.4 % to C. pelargi 136/3T, respectively. In silico DNA-DNA hybridization values for 812CHT and W8T were 22.1 % among the two strains and 35.3 and 21.7 % to C. pelargi 136/3T, respectively. These data not only demonstrate that strain W8T is a representative of a novel species, but despite the high 16S rRNA gene sequence similarity to C. pelargi, strain 812CHT is also a representative of another novel species. All three strains possessed corynemycolic acids and contained meso-diaminopimelic acid as the diagnostic diamino acid of the peptidoglycan. The two strains, 200CHT and W8T, are distinguished from each other and established Corynebacterium species phylogenetically and phenotypically. In conclusion, three novel species of the genus Corynebacterium are proposed, namely Corynebacteriumpseudopelargi 812CHT (=LMG 30627T=CCM 8832T), Corynebacterium choanae 200CHT (=LMG 30628T=CCM 8831T) and Corynebacteriumgerontici W8T (=LMG 30629T=CCM 8833T), respectively.