Phospho- and sulfolipids as biomarkers of Caulobacter sensu lato, Brevundimonas and Hyphomonas

Abstract

Summary Phospholipids of type strains and isolates of Caulobacter, Brevundimonas, Hyphomonas and Mycoplana bullata were studied by chromatographic and spectroscopic methods. Using tandem mass spectrometry individual phospholipids were analyzed and their structures elucidated. From the 69 strains included in this study 26 new phosphoglucolipids and two new sulfoquinovosyl-diacylglycerols could be identified. While more than 30 different fatty acids were found in the phospholipid fraction of Caulobacter and Brevundimonas only seven different fatty acids occur within the 26 different phosphoglucolipids identified. The distribution of the different types of phospholipids, especially of the sulfoquinovosyl-, glucoronotaurine amide- and phosphatidyl-glucopyranosyl-diacylglycerols, leads to the identification of four different phenotypic groups of these bacteria in agreement with the phylogeny published by Stahl et al. in 1992. One comprises Caulobacter sensu stricto with the type strain C. vibrioides , the second the type strains of Brevundimonas together with a considerable number of Caulobacter species and the third the halophilic Caulobacter spp . around C. maris . The latter group lacks the phosphatidyl-glucopyranosyl-diacylglycerols but contains sulfoquinovosyl- and glucuronotaurine amide diacylgly- cerols. They can be discerned from Hyphomonas by the occurrence of sulfoquinovosyl-diacylglycerols which are absent in strains of the genus Hyphomonas .