A total of 17 -like isolates were obtained from blood during a septicaemia outbreak in a neonatal unit, Tanzania, that could not be assigned based on phenotypic test to any existing species. Eight representative outbreak isolates were investigated in detail. Fermentation characteristics, biochemical assays and fatty acid profiles for taxonomic analysis were determined and supplemented with information derived from whole genome sequences. Phenotypic and morphological tests revealed that these isolates were Gram-stain-negative, rod-shaped, highly motile and facultatively anaerobic. The fatty acid profile was similar to those of the type strains for all recognized species, with quantitative differences in C, Cω7 and C cyclo fatty acids. Whole genome sequencing was used to identify taxonomically relevant characteristics, i.e. for 16S rRNA gene sequence analysis, multi-locus sequence analysis (MLSA), DNA-DNA hybridization (DDH) and average nucleotide identity (ANI). Draft genomes were approximately 4.9 Mb in size with a G+C content of 56.0 mol%. The 16S rRNA gene sequence of these eight isolates showed >97 % similarity to all species, while MLSA clustered them closely with the type strains of and . These eight strains showed less than 70 % DDH identity with the type strains of species. In addition, less than 95 % ANI to the type strains of species was observed. From these results, it is concluded that these isolates possess sufficient characteristics to differentiate them from all recognized species, and should therefore be considered as representing a novel species. The name sp. nov. is proposed with EB-247 ( = DSM 29888 = NCCB 100573) as the type strain.
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http://dx.doi.org/10.1099/ijsem.0.000821 | DOI Listing |
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