| Summary: | The structures of two major phosphoglycolipids from the thermophilic bacteria Thermus oshimai NTU-063, Thermus thermophilus NTU-077, Meiothermus ruber NTU-124, and Meiothermus taiwanensis NTU-220 were determined using spectroscopic and chemical analyses to be 2′-O-(1,2-diacyl-sn-glycero-3-phospho) -3′-O-(α-N-acetyl-glucosaminyl)-N-glyceroyl alkylamine [PGL1 (1)] and the novel structure 2′-O-(2-acylalkyldio-1-O-phospho)-3′-O-(α-N-acetylglucosaminyl)-N-glyceroyl alkylamine [PGL2 (2)]. PGL2 (2) is the first phosphoglycolipid identified with a 2-acylalkyldio-1-O-phosphate moiety. The fatty acids of the phosphoglycolipids are mainly iso-C15:0, -C16:0, and -C17:0 and anteiso-C15:0 and -C17:0. The ratios of PGL2 (2) to PGL1 (1) are significantly altered when grown at different temperatures for three strains, T. thermophilus NTU-077, M. ruber NTU-124, and M. taiwanensis NTU-220, but not for T. oshimai NTU-063. Accordingly, the ratios of iso- to anteiso-branched fatty acids increase when grown at the higher temperature.
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