The pattern
of Chromatocurvus halotolerans DSM 23344T was characterized by an aminophospholipid and an unidentified phospolipid in addition to the dominating polar lipids phosphatidylglycerol and phosphatidylethanolamine (Table 1), so that it could be distinguished from the profiles of Ivo14T, H. rubra and C. litoralis. However, the profile of Chromatocurvus halotolerans did match the polar lipid patterns of type strains of the chemoheterotrophic species H. salexigens and H. mediterranea that were obtained in this study and differed slightly from results published elsewhere [17, 19]. The whole-cell fatty acid patterns of the strains Ivo14T, Chromatocurvus halotolerans CP673451 datasheet DSM 23344T and H. rubra DSM 19751T were determined upon growth
on Marine Agar 2216 plates. The results were compared with the cellular fatty acid profiles of the type strains of C. litoralis and two related chemoheterotrophic Haliea species (Table 2). The fatty acid pattern of H. rubra DSM 19751T could be distinguished from all other type strains by the low content of 17:0, 17:1 and 10:0 3OH fatty acids, whereas C. litoralis DSM 17192T was unique in the synthesis of the unusual 16:1 ω6 unsaturated fatty acid, which suggests an affiliation of both type strains to different genera. Further analyses of the cellular Peptide 17 ic50 fatty acid profiles of the four BChl a-containing strains were performed upon cultivation in SYPHC liquid medium with different oxygen concentrations in the head space gas atmosphere (see Additional file 1). In a previous study it was found that in C.
litoralis the position of the double bond in the unsaturated fatty acids 16:1 and 18:1 depends on the oxygen saturation and was shifted from the ω7 to the ω6 position under conditions of oxygen limitation [8]. It is known that several pathways for the synthesis of unsaturated fatty acids exist in proteobacteria. selleck inhibitor An oxygen-dependent pathway is based on desaturases that introduce double bonds in membrane-bound fatty acids by oxidation with molecular oxygen. An alternative oxygen-independent pathway introduces double bonds during elongation of the fatty acid chain [35]. Hence, we propose that C. litoralis expresses two distinct desaturases for the fatty acids 16:1 ω7 (Δ9 desaturase, JNJ-64619178 encoded by the proposed gene KT71_07544) and 18:1 ω7 (Δ11 desaturase, probably encoded by KT71_03222), whereas the ω6 unsaturated fatty acids are produced by an oxygen-independent pathway. A similar effect could not be detected in the strains Ivo14T, Chromatocurvus halotolerans DSM 23344T and H. rubra DSM 19751T (Additional file 1). While in the analyzed fatty acid patterns of strain Ivo14T neither the abundance of the unsaturated fatty acids 18:1 ω7 nor 16:1 ω7 correlated with the oxygen saturation, in Chromatocurvus halotolerans a decrease of the portion of 18:1 ω7 from 36.6% to 25.8% under conditions of oxygen limitation was detected, which indicates involvement of an oxygen-dependent desaturase.