THE PHOSPHOLIPID ESTER-LINKED FATTY-ACID COMPOSITION OF MEMBERS OF THE FAMILY HALOMONADACEAE AND GENUS FLAVOBACTERIUM - A CHEMOTAXONOMIC GUIDE

The phospholipid ester-linked fatty acids (PLFA) from members of the family Halomonadaceae and the genus Flavobacterium were analyzed in detail by capillary GC and GC-MS. Precise monounsaturated double bond position and geometry was determined by GC-MS analysis of the dimethyl disulphide adducts of the monounsaturated fatty acids. No clear distinction was observed between members of the two genera Halomonas and Deleya based upon PLFA composition. The major PLFAs detected in strains from the two genera were 18:1w7c, 16:1w7c and 16:0. These three fatty acids accounted for greater than 95% of the total PLFA detected. The PLFA profiles of "Flavobacterium salegens" (ACAM 48) and "Flavobacterium gondwanense" (ACAM 44), proposed new species of moderately halophilic bacteria isolated from Organic Lake, Antarctica, were characterized by high abundances of i15:0, a15:0, 15:0, i15:1w10c, a15:1w10c and i16:0. The two species were distinguishable from each other based on their PLFA and hydroxy fatty acid profiles. The position of the double bond in the branched C15 monounun-saturated fatty acids is unusual, and may be a taxonomic feature of these bacteria. It may also be possible to use these signature fatty acids (i and a15:1w10c) in microbial ecology studies of antarctic saline lakes where the presence and relative importance of these bacteria is being investigated.