Polar lipid fatty acids, LPS-hydroxy fatty acids, and respiratory quinones of three Geobacter strains, and variation with electron acceptor.

The polar lipid fatty acids, lipopolysaccharide hydroxy-fatty acids, and respiratory quinones of Geobacter metallireducens str. GS-15, Geobacter sulfurreducens str. PCA, and Geobacter bemidjiensis str. Bem are reported. Also, the lipids of G. metallireducens were compared when grown with Fe(3+) or nitrate as electron acceptors and G. sulfurreducens with Fe(3+) or fumarate. In all experiments, the most abundant polar lipid fatty acids were 14:0, i15:0, 16:1 omega 7c, 16:1 omega 5c, and 16:0; lipopolysaccharide hydroxy-fatty acids were dominated by 3oh16:0, 3oh14:0, 9oh16:0, and 10oh16:0; and menaquinone-8 was the most abundant respiratory quinone. Some variation in lipid profiles with strain were observed, but not with electron acceptor.

Measuring soil microbial community diversity using polar lipid fatty acid and denaturing gradient gel electrophoresis data.

The possibility of calculating useful microbial community diversity indices from environmental polar lipid fatty acid and 16S rDNA PCR-DGGE data was investigated. First, the behavior of the species richness, Shannon's, and Simpson's diversity indices were determined on polar lipid fatty acid profiles of 115 pure cultures, communities constructed from those profiles with different numbers of species, and constructed communities with different distributions of species. Differences in the species richness of these artificial communities was detected by all three diversity indices, but they were insensitive to the evenness of the distribution of species. Second, data from a field experiment with substrate addition to soil was used to compare the methods developed for lipid- and DNA-based diversity indices. Very good agreement was found between indices calculated from environmental polar lipid fatty acid profiles and denaturing gradient gel electrophoresis profiles from matched samples (Pearson's correlation coefficient r=0.95-0.96). A method for data pre-treatment for diversity calculations is described.

Archaebacterial ether lipid diversity analyzed by supercritical fluid chromatography: integration with a bacterial lipid protocol.

A strategy has been developed for archaebacterial lipid analysis which provides three times the information to describe archaebacterial isolates and is compatible with simultaneous eubacterial/eukaryotic lipid analysis of environmental samples. Eubacterial and micro-eukaryotic biomass, community structure, and nutritional status have been routinely defined in environmental samples by lipid analysis. Lipid profiles are also useful in eubacterial identification and taxonomy. Polar lipid or whole cell ester-linked fatty acids are generally analyzed by gas chromatography-mass spectroscopy. Archaebacteria are characterized by their ether-linked membrane lipids. There is, however, less diversity in the side chains of archaebacterial membrane lipids as compared the eubacterial ester-linked membrane lipids. The information content of the archaebacterial lipid profile was increased by separately analyzing the polar lipid, glycolipid, and lipid-extracted residue fractions. Identification and quantification were performed by supercritical fluid chromatography. Results are presented for three species of methanogens and four thermoacidophile isolates, and compared with a literature review.