The conversion of cis into trans unsaturated fatty acids in Pseudomonas putita P8: evidence for a role in the regulation of membrane fluidity

Abstract

The physiological significance of trans unsaturated fatty acids, which are constituents of membrane lipids of the phenol-degrading bacterium Pseudomonas putita P8, was studied. The addition of phenol or phenol derivatives to the cells induced the formation of trans unsaturated fatty acids, yielding an overall maximal amount of 41.3°70 of total fatty acids. The inhibition of de-novo lipid synthesis by cerulenin prevented the change in the degree of saturation in the lipids. However, the cells could still respond to phenols with an amplified conversion of cis into trans unsaturated fatty acids, which is apparently a post-synthetic mechanism of isomerization of the double bond. The cis/trans conversion correlated with growth inhibition induced by toxic concentrations of 4-chlorophenol, whereas only growing cells were able to change the degree of saturation. In cells that were protected against phenol by immobilization in calcium alginate, the conversion of cis into trans fatty acids occurred at higher toxin concentrations compared with free ceils. Cells entering the stationary growth phase increased the proportion of saturated to unsaturated fatty acids but maintained a constant trans/cis ratio. P. putida P8 reacted to an increase or decrease in the growth temperature with an appropriate change in the ratio of saturated to unsaturated fatty acids and in ceils inhibited by cerulenin with a change in the trans/cis ratio. This study shows that the physiological role of the cis/trans conversion is probably the regulation of membrane fluidity when the most important mechanism for this, the modification of the degree of saturation, cannot be used by the cells due to inhibition of growth and lipid biosynthesis.

Pseudomonas putidaNCTC 10936 Balances Membrane Fluidity in Response to Physical and Chemical Stress by Changing the Saturation Degree and theTrans/cisRatio of Fatty Acids

“…12) However, the ETP of P. putida NCTC 10936 could be stabilized by the conversion of cis to trans unsaturated fatty acids, 13) which is known to occur, as well as changes in the saturation degree, in several strains of P. putida. [14][15][16][17] This raises the question of whether this too is mediated by adaptive reductions in the fluidity of the cytoplamic membrane. Therefore, in the study reported here, the effects of both temperature and 4-CP on the fatty acid composition and fluidity of the lipids of P. putida NCTC 10936 were investigated.…”

Changes in Membrane Fluidity and Fatty Acid Composition ofPseudomonas putidaCN-T19 in Response to Toluene

“…The results are consistent with previous observations that the change in the ratio of cis-to transfatty acids is an adaptive mechanism in microorganisms that can grow in the presence of solvent. 4,14,15,20) Our results show that toluene aŠects bacterial cells in more ways than its simply having ‰uidizing eŠects on membranes.…”

“…14,15) This could kill the cells by causing eOEux of cell metabolites and ions from the cell interior. The phenoladapted cells of P. putida P8 showed less eOEux of K + ion than non-adapted cells, which was due to the change in the membrane structure to respond phenol.…”

“…The phenoladapted cells of P. putida P8 showed less eOEux of K + ion than non-adapted cells, which was due to the change in the membrane structure to respond phenol. 14,15) Toluene has a high partitioning action into cell membranes, because this solvent is very lipophilic. The hydrophobic membrane probe DPH would partition more into cells once membrane structures become more ‰uid by addition of toluene, giving the lower ‰uorescence value in vitro (Fig.…”

Biosynthesis oftransFatty Acids in a Fungus,Cladosporium sphaerospermum, and Some Bacteria Isolated from Fish Viscera

“…These results indicate that the trans fatty acids in C. sphaerospermum 7CS7-5 are not involved in adaptation to changes in growth temperature or protection from toxic substances, while trans fatty acids in bacterial isolates responded like those in Pseudomonas, Vibrio, etc., as reported previously. 2 ble bond-positional isomers (Table II). As for 18: Ic, the majority in C. sphaerospermum 7CS7-5 was OA (cisA9), and a small amount of cis-vaccenic acid (cisA II) was found in one fungus, 3PIO-9.…”