THE EFFECT OF GROWTH TEMPERATURE ON THE PHOSPHOLIPID AND FATTY ACYL COMPOSITIONS OF NONPROTEOLYTIC CLOSTRIDIUM-BOTULINUM

A non-proteolytic strain of Clostridium botulinum (NCIB 4270) was foun d to have a complex lipid composition, comprising five major phosphoru s-containing lipids: phosphatidylethanolamine (PE), phosphatidylglycer ol (PG), diphosphatidylglycerol (DPG), phosphatidylserine (PS) and a g lycophospholipid of unknown structure (GPL), in order of abundance. Ch anging the growth temperature did not alter the lipid composition eith er qualitatively or quantitatively. The main fatty acyl components of the lipids are 14:0, 16:0 and 16:1. When the growth temperature was lo wered from 37 to 8 degrees C, there was an increase in 14:0 from 16.4 to 37.5%, an increase in 16:1 from 10.5 to 22.5%, and a decrease in th e proportion of 16:0 from 40.3 to 19.1%. There was also a decrease in the proportion of cyclopropane fatty acids (15:0cyc and 17:0cyc) from 7.3 to 0.5%, and in the equivalent chain length of the total fatty aci ds from 15.9 to 15.3 as the temperature was lowered. The same temperat ure-dependent changes occurred in the five major lipid classes examine d. Despite reports of the presence of plasmalogenic forms of phospholi pids (i.e. those lipids which have the acyl chain in the sn-l position replaced by an alk-1-enyl group) in some Clostridium spp., none were detected in C. botulinum NCIB 4270 using either commercially available spray reagents or by gas-liquid chromatographic analysis of the produ cts or acid methanolysis of total lipid extracts. It is concluded that non-proteolytic C. botulinum lacks plasmalogens, typical of other clo stridia, in its membranes and instead modulates its fatty acid composi tion in response to temperature changes in a manner that is typical of other (non-clostridial) bacteria. (C) 1998 Elsevier Science B.V.