Phylogenetic relationships among marine Alteromonas-like proteobacteria: emended description of the family Alteromonadaceae and proposal of Pseudoalteromonadaceae fam. nov., Colwelliaceae fam. nov., Shewanellaceae fam. nov., Moritellaceae fam. nov., Ferri

The phylogenetic relationships among marineAlteromonas-like bacteria of the generaAlteromonas,Pseudoalteromonas,Glaciecola,Thalassomonas,Colwellia,Idiomarina,Oceanimonas,Oceanisphaera,Shewanella,Moritella,Ferrimonas,Psychromonasand several other genera of the ‘Gammaproteobacteria’ were studied. Results of 16S rRNA gene sequence analyses revealed that some members of these genera formed several coherent groups at the family level. Characteristic signature oligonucleotides for studied taxa were defined. Signature positions are divided into three classes: (i) single compensatory mutations, (ii) double compensatory mutations and (iii) mutations affecting nucleotides not paired in the secondary structure. The 16S rRNA gene sequence similarity level within genera was 93 % or above. This value can be a useful additional criterion for genus discrimination. On the basis of this work and previous polyphasic taxonomic studies, the circumscription of the familyAlteromonadaceaeis limited to the generaAlteromonasandGlaciecolaand the creation is proposed of the familiesPseudoalteromonadaceaefam. nov. to accommodate bacteria of the generaPseudoalteromonasandAlgicolagen. nov. (formerlyPseudoalteromonas bacteriolytica) andColwelliaceaefam. nov. to accommodate bacteria of the generaColwelliaandThalassomonas. Bacteria of the generaOceanimonasandOceanisphaeraformed a robust cluster and shared common signature oligonucleotides. Because of deep branching and lack of association with any other genus, the following families are proposed that include single genera:Idiomarinaceaefam. nov.,Psychromonadaceaefam. nov.,Moritellaceaefam. nov.,Ferrimonadaceaefam. nov. andShewanellaceaefam. nov. Finally, this study also revealed that [Hyphomicrobium]indicumshould be reclassified asPhotobacterium indicumcomb. nov.