A taxonomic study to establish the relationship between exopolysaccharide-producing bacterial strains living in diverse hypersaline habitats.

This study was undertaken to identify exopolysaccharide-producing bacteria gathered from 18 hypersaline habitats. Phenotypic studies performed with 134 isolates revealed the majority of them to be Gram-negative rods with respiratory metabolism, belonging to the genus Halomonas. A numerical analysis of the 114 phenotypic data showed that at an 80% similarity level most of the strains (121) could be grouped into six phenotypic groups. Phenon A included 25 new isolates and the reference strain of Halomonas eurihalina, and phenon B was formed by 77 new isolates and Halomonas maura. Phenon C was also related to H. maura although to a lesser extent than strains in group B. Three phena (D, E, and F) could not be grouped with any of the reference strains and may represent new taxa; their G + C contents and DNA-DNA hybridization data corroborated this hypothesis. Results of this work proved that the most abundant halophilic species EPS producer in hypersaline habitats was H. maura, followed by H. eurihalina.