Halomonas sp. nov., an EPA-producing mesophilic marine isolate from the Indian Ocean.

Marine samples from the Indian Ocean were used to isolate and characterize the organisms with respect to their fatty acid profiles. Six mesophilic isolates (MBRI 6, MBRI 8, MBRI 9, MBRI 10, MBRI 12 and MBRI 13) were obtained from three different water samples. They were i) Gram-negative, ii) catalase positive, iii) produced acid from glucose and maltose, iv) tolerated 5 to 15% NaCI v) except MBRI 9, showed pH tolerance in the range of 5.0 to 9.0 with optimum pH 7.0 to 8.0 v) grew well at 30 degrees C and were able to grow in the range of 15 to 45 degrees C. EPA, an essential omega-3 fatty acid, was produced by these isolates in the range of 12 to 60% at 30 degrees C. MBRI 12 was found to be a potential source as it produced 60% EPA. This isolate was further identified by partial 16S rDNA sequencing and phylogenetic analysis revealed that the strain belonged to Gammaproteobacteria and was closely related to Halomonas bolviensis (96% sequence similarity, 570 bp). Thus a new genus of Halomonas may be included in earlier reported EPA- producing prokaryotic genera affiliated to the Gammaproteobacteria.