PHENOTYPIC VARIATION OF LIPID-COMPOSITION IN BURKHOLDERIA-CEPACIA - ARESPONSE TO INCREASED GROWTH TEMPERATURE IS A GREATER CONTENT OF 2-HYDROXY ACIDS IN PHOSPHATIDYL ETHANOL AMINE AND ORNITHINE AMIDE LIPID

Burkholderia cepacia produces an unusual range of polar lipids, which includes two forms each of phosphatidylethanolamine (PE) and ornithine amide lipid (OL), differing in the presence or absence of 2-hydroxy f atty acids. By using chemostat cultures in chemically defined media, v ariations in the lipid content and the proportions of individual lipid s have been studied as a function of (a) growth temperature, (b) growt h rate and (c) growth-limiting nutrient (carbon. magnesium, phosphorus or oxygen). Total cellular lipid in carbon-limited cultures was lowes t at high growth temperatures and low growth rates. Increases in growt h temperature over the range 25-40 degrees C led to increases in the p roportions of molecular species of PE and OL containing I-hydroxy acid s, without changing the PE:OL ratio. Growth temperature did not alter the balance between neutral and acidic lipids, but the contribution of phosphatidylglycerol to the latter increased with rising growth tempe rature and growth rate. Pigmentation of cells and the presence of flag ella were also temperature-dependent. Change in growth rate also affec ted the PE:OL ratio and the extent to which monoenoic acids were repla ced by their cyclopropane derivatives. Whereas similar lipid profiles were found for carbon-. megnesium- and oxygen-limited cultures, ornith ine amides were the only polar lipids detected in phosphorus-limited c ells.