Temperature adaptation in Lactobacillus fermentum: interconversions of oleic, vaccenic and dihydrosterulic acids

Abstract

The interchange of octadecenoic acids and dihydrosterulic acid was a response of aerobically growing LactobaciZZus fermenturn to changes in growth temperature. Oleic and vaccenic acid contents decreased both at temperatures below 20 "C and above 26 "C, showing mirror image behaviour, with a concomitant increase in dihydrostemlic acid. A temperature-dependent shift from vaccenic to oleic acid synthesis, and the conversion of the latter to dihydrosterulic acid was responsible for the overall change. Consequently, the degree of fatty acid unsaturation decreased at temperatures above 26 "C, whereas the degree of cyclization increased. The converse occurred below 20 "C. The relative amount of lactobacillic acid, total cellular fatty acid content, and mean fatty acid chain length were practically temperature-independent. The occurrence of oleic acid is thought to be related to aerobic growth conditions.

Effects of Polyunsaturated Fatty Acids in Growth Medium on Lipid Composition and on Physicochemical Surface Properties of Lactobacilli

“…The fourth major group of fatty acids in the present study was 19:cyc, especially dihydrosterculic acid. Previous reports regarded dihydrosterculic and lactobacillic acids, formed by methylenation of oleic and vaccenic acids, respectively, as the major fatty acids in lactobacilli (3,7,10,20). Even though lactobacillic acid is the most frequently reported fatty acid in lactobacilli, we did not identify it in L. delbrueckii subsp.…”

“…Indeed, there is experimental evidence that anaerobic lactobacilli may possess an oxygen-consuming desaturase system to cope with environmental stress (7). However, it must be emphasized that the biosynthetic routes for fatty acids in lactobacilli still have not been studied extensively (7,10,20).…”

Physiological and Transcriptional Response ofLactobacillus caseiATCC 334 to Acid Stress

“…Because FA biosynthesis in bacteria is an energyintensive process (55), the capability to modify existing CMFAs offers cells a less taxing means to adjust membrane structure, and at least three distinct enzymes have been found to catalyze these reactions in bacteria: phospholipid acyl desaturase, cyclopropane synthase (Cfa), and FA cis-trans isomerase (54). The L. casei ATCC 334 genome appears to encode only one of these enzymes, Cfa, which catalyzes the addition of a methylene residue across the cis double bond of C 16:1n(9) , C 18:1n (9) , or C 18:1n(11) unsaturated FAs to form an unsaturated cyclopropane derivative (49). Thus, the concomitant decrease in C 18:1n (11) and increase in C 19:0(11c) detected in the cytoplasmic membrane content of acid-adapted cells (Table 2) can be directly attributed to Cfa activity on existing C 18:1n (11) .…”

Growth of probiotic lactobacilli in the presence of oleic acid enhances subsequent survival in gastric juice

“…The fatty acid composition of the bacterial membrane depends upon a number of factors, including growth temperature (Suutari & Laakso, 1992), pH (Fozo & Quivey, 2004b), growth phase (Veerkamp, 1971), cultivation medium composition (Johnsson et al, 1995) and NaCl concentration (Machado et al, 2004). When LAB were grown in a medium supplemented with Tween 80 [polyoxyethylenesorbitan mono-oleate, which consists of up to 90 % oleic acid; Partanen et al, 2001], oleic acid was incorporated into the membranes (Johnsson et al, 1995).…”