Shewanella hafniensis sp. nov. and Shewanella morhuae sp. nov., isolated from marine fish of the Baltic Sea

M. Satomi, Birte Fonnesbech Vogel, Lone Gram, K. Venkateswaran

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Abstract

Two novel species belonging to the genus Shewanella are described on the basis of their phenotypic characteristics, phylogenetic analyses of 16S rRNA and gyrB gene sequences and levels of DNA-DNA hybridization. A total of 47 strains belonging to two novel Gram-negative, psychrotolerant, H2S-producing bacterial species were isolated from marine fish (cod and flounder) caught from the Baltic Sea off Denmark. The phenotypic characteristics of strains belonging to group 1 (14 strains) indicated that these represented a non-sucrose-assimilating variant of Shewanella baltica with a DNA G+C content of 47{middle dot}0 mol%. Strains of group 2 (33 isolates) did not utilize the carbon substrates assimilated by S. baltica except gluconate, N-acetylglucosamine and malate. Their DNA G+C content was 44{middle dot}0 mol%. Phylogenetic analysis of the 16S rRNA gene sequence data placed the two novel species within the genus Shewanella. Group 1 strains showed greatest sequence similarity to Shewanella putrefaciens ATCC 8071T (99{middle dot}0 %) and with S. baltica NCTC 10375T (98{middle dot}3 %). However, gyrB gene sequence analysis showed these isolates to share only 90{middle dot}0 % sequence similarity with S. putrefaciens ATCC 8071T and 93{middle dot}9 % with S. baltica NCTC 10375T. Similarly, DNA-DNA hybridization experiments revealed DNA relatedness levels of 38 % between the group 1 isolates and S. putrefaciens ATCC 8071T and 43 % with S. baltica NCTC 10375T. The group 2 strains shared less than 97 % 16S rRNA gene sequence similarities with recognized Shewanella species. Comparisons between the two novel species indicated 16S rRNA gene sequence similarity of [~]98 %, gyrB gene sequence similarity of [~]89 % and DNA-DNA reassociation values of 20-34 %. Based on the evidence presented, two novel species, Shewanella hafniensis sp. nov. (type strain P010T=ATCC BAA-1207T=NBRC 100975T) and Shewanella morhuae sp. nov. (type strain U1417T=ATCC BAA-1205T=NBRC 100978T), are described.
Original languageEnglish
JournalInternational Journal of Systematic and Evolutionary Microbiology
Volume56
Issue number1
Pages (from-to)243-249
ISSN1466-5026
DOIs
Publication statusPublished - 2006

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