Fatty acids in phospholipids of cells, cysts, and germinating cysts of Azotobacter vinelandii

Abstract

Cyclopropane fatty acids constitute 25% of the phospholipid acyl groups in cysts of Azotobacter vinelandii. These are lost by dilution during germination when the synthesis of those fatty acids characteristic of vegetative cell phospholipids commences.Azotobacter vinelandii can be induced to encyst by shifting an exponentially growing culture from glucose as a carbon source to 0.2% f8-hydroxybutyrate (9). In tracing the metabolic rate of fB-hydroxybutyrate during this cell-to-cyst transition, we have noted (i) that a significant amount of fl-hydroxybutyrate is incorporated into membrane as acyl groups of phospholipids and (ii) that the cyclopropane fatty acids cis-

Lipid metabolism during encystment of Azotobacter vinelandii

“…The identical process has been shown in AR1 and AR2 and their specific activities. usly to occur in BHB-induced encystment The validity of these measurements was estabinelandii (16).…”

“…When the nonencapsulated strain, A. vinelandii OP, was cultured in BHB, the cells rounded up aTotal lipid extract was subjected to mild alkaline methanolysis (19). b Determined by gas chromatography as previously described (16).…”

“…This implies that turnover of fatty acids occurs during this period. Another event involving the fatty acids which begins at about 6 h postinduction is the formation of C17A and C19, fatty acids from the corresponding unsaturated acids C16l and C18:1 (16); possibly this occurs by the addition of a methylene group donated by S-adenosylmethionine to the double bond as it does in other organisms (3,8,9).…”

Sporulation in Bacillus subtilis is independent of membrane fatty acid composition

“…Examples of developmental changes in the fatty acid composition of membranes have been reported. In Gluconobacter oxydans (7) and Azotobacter vinelandii (17), fatty acids with bulky chains appear during differentiation. Bulla et al (3) found a difference between the fatty acid composition of vegetative cells and spores of Bacillus thuringiensis.…”