ABSTRACTRecent metagenomic studies on saltern ponds with intermediate salinities have determined that their microbial communities are dominated by bothEuryarchaeotaand halophilic bacteria, with a gammaproteobacterium closely related to the generaAlkalilimnicolaandArhodomonasbeing one of the most predominant microorganisms, making up to 15% of the total prokaryotic population. Here we used several strategies and culture media in order to isolate this organism in pure culture. We report the isolation and taxonomic characterization of this new, never before cultured microorganism, designated M19-40T, isolated from a saltern located in Isla Cristina, Spain, using a medium with a mixture of 15% salts, yeast extract, and pyruvic acid as the carbon source. Morphologically small curved cells (young cultures) with a tendency to form long spiral cells in older cultures were observed in pure cultures. The organism is a Gram-negative, nonmotile bacterium that is strictly aerobic, non-endospore forming, heterotrophic, and moderately halophilic, and it is able to grow at 10 to 25% (wt/vol) NaCl, with optimal growth occurring at 15% (wt/vol) NaCl. Phylogenetic analysis based on 16S rRNA gene sequence comparison showed that strain M19-40Thas a low similarity with other previously described bacteria and shows the closest phylogenetic similarity with species of the generaAlkalilimnicola(94.9 to 94.5%),Alkalispirillum(94.3%), andArhodomonas(93.9%) within the familyEctothiorhodospiraceae. The phenotypic, genotypic, and chemotaxonomic features of this new bacterium showed that it constitutes a new genus and species, for which the nameSpiribacter salinusgen. nov., sp. nov., is proposed, with strain M19-40T(= CECT 8282T= IBRC-M 10768T= LMG 27464T) being the type strain.
Isolation and Characterization of Indole Acetic Acid Producing Halophilic Bacteria from Salt Affected Soil of Rice–Shrimp Farming System in the Mekong Delta, Vietnam
