Sulfitobacter mediterraneus sp. nov., a new sulfite-oxidizing member of the α-Proteobacteria

Analysis of PCR products of 16S rDNA of 680 isolates from Mediterranean Sea mesocosm experiments with taxon-specific 16S rDNA oligonucleotides revealed that 262 isolates belonged to the alpha subclass of the class Proteobacteria. partial 16S rDNA sequence analysis of selected isolates and oligonucleotide probing with a Sulfitobacter-specific 16S rDNA probe affiliated 33 strains to the genus Sulfitobacter. Analysis of the HaeIII digest pattern of 16S rDNA revealed the presence of two groups; while 30 strains showed a pattern identical with that obtained for Sulfitobacter pontiacus DSM 10014(T), a second group of three strains had a unique pattern that was different from that of the type strain. Five isolates of group 1 and one isolates of group 2, strain CH-B427(T), were selected for detailed taxonomic analysis. All six isolates closely resembled the type strain Sulfitobacter pontiacus DSM 10014(T) in physiological reactions. However, strain CH-B427(T) differed quantitatively in the composition of fatty acids from Sulfitobacter pontiacus DSM 10014(T) and showed only 98.2% 16S rDNA sequence similarity with strain DSM 10014(T). DNA-DNA reassociation value obtained for strains DSM 10014(T) and CH-B427(T) revealed 46% similarity. Based on the results of DNA-DNA reassociation and discrete differences in the nucleotide composition of 16S rDNA, a new species of the genus Sulfitobacter is proposed, designated Sulfitobacter mediterraneus sp, nov., the type strain being strain CH-B427(T) (= DSM 12244(T)).