Fatty Acid Compositions of Paracolons: Arizona, Citrobacter, and Providencia

The fatty acid compositions of stationary-phase cultures of Arizona arizonae, Citrobacter freundii, Providencia alcalifaciens, Providencia stuartii, and Providencia sp. were studied. The major fatty acids of A. arizonae, C. freundii, and Providencia were 16:0, 16:1, 17:cyclopropane, and 19:cyclopropane. The fatty acid compositions of the two strains of A. arizonae examined were similar to each other, but the three strains of C. freundii differed from one another in their fatty acid compositions. In both A. arizonae and C. freundii, the relative quantities of saturated, unsaturated, and cyclopropane fatty acids were similar to those which have been found in stationary-phase cultures of other members of the Enterobacteriaceae. The three strains of Providencia also differed from one another in their fatty acid compositions. In all three strains, the total quantity of unsaturated fatty acids was larger and that of the cyclopropane fatty acids was smaller than those found in stationary-phase cultures of other enteric bacteria.     

Evidence for the Existence of an Aerobic Pathway for Synthesis of Monounsaturated Fatty Acids by Alcaligenes faecalis

Studies on the composition of total fatty acids of Alcaligenes faecalis harvested at different growth phases have been carried out. Ability of the organism to desaturate palmitic and stearic acid has also been tested. The organism contained palmitic (16:0), stearic (18:0), palmitoleic (16:1), cis-vaccenic (18:1), cyclopropane (17: big dn tri, open and 19: big dn tri, open), and three hydroxy acids. Increase in cyclopropane acids and corresponding decrease in monounsaturated acids in direct proportion to the age of the culture were observed, whereas other fatty acids remained relatively unaltered. A growing culture of the organism was found to desaturate [1-(14)C]palmitic acid supplied in the medium to hexadecanoic acid. Resting cells desaturated [1-(14)C]palmitic and [1-(14)C]stearic acid giving rise to about 50% of (14)C in the COOH group of corresponding monounsaturated fatty acids.     

Effect of growth temperature on lipid composition of Streptococcus faecium

The effect of growth temperature on the lipid and fatty acid composition of Streptococcus faecium has been studied. No differences in the qualitative composition of S. faecium lipids were observed. In all isolated fractions (neutral lipids, glycolipids, and phospholipids plus other polar lipids), the major fatty acids were palmitic (C-16:0), palmitoleic (C-16:1), octadecenoic (C-18:1), and cyclopropane (C-19:0). Changes in the fatty acid composition of the different fractions were observed which depended on growth temperature; the most significant one was the decrease of octadecenoic acid and the increase of palmitic acid in glycolipids and polar lipids as the temperature increased. The level of cyclopropane C-19:0 was approximately eightfold lower at 8 degrees C than at the other temperatures tested (20, 30, and 45 degrees C).     

Fatty acid composition of selected prosthecate bacteria

The cellular fatty acid composition of 14 strains of Caulobacter species and types, two species of Prosthecomicrobium, and two species of Asticcacaulis was determined by gas-liquid chromatography. In most of these bacteria, the major fatty acids were octadecenoic acid (C18:1), hexadecenoic acid (C16:1) and hexadecanoic acid (C16:0). Some cyclopropane and branched chain fatty acids were detected in addition to the straight chained acids. Hydroxytetradecanoic acid was an important component of P. enhydrum but significant amounts of hydroxy acids were not detected in other prosthecate bacteria examined.Abbreviations DEGS diethylene glycol succinate - A measare of association Dedicated to Prof. R. Y. Stanier on the occasion of his 60th birthday     

Adaptational changes of fatty acid composition and the physical state of membrane lipids following the change of growth temperature in Yersinia enterocolitica.

Yersinia enterocolitica is capable of growing in a broad range of temperatures from 4 to 45 C. How this organism alters its membrane lipids in response to the change of growth temperature is very interesting. The fatty acids of membrane lipids of cells cultured at 5, 15, 25 and 37 C were analyzed and the physical states of these membrane lipids were characterized. The major phospholipids of this bacterium were phosphatidylethanolamine, phosphatidylglycerol, cardiolipin, lysophosphatidylglycerol and lysophosphatidylethanolamine. No significant difference in phospholipid composition in response to culture temperatures was observed. It was reported in our previous paper that the major fatty acids of membrane phospholipids of Y. enterocolitica were C15:0, C16:0, C16:1, cyclopropane C17:0 and C18:0. Some differences in the fatty acid composition were, however, observed with the change of culture temperature. When the culture temperature was raised, the saturated and cyclopropane fatty acids substantially increased and the unsaturated ones decreased. A reverse phenomenon was observed when culture temperature was lowered. From the viewpoints of membrane physical state, adaptational changes were analyzed using a nylon microcapsule method. Phase transition in membrane lipids of cells grown at each culture temperature took place in the range of about 5 C below and about 10 C above the culture temperature. It is, therefore, considered that Y. enterocolitica maintains its membrane rigidity and fluidity in response to growth temperature by changing the membrane fatty acid composition.     

Characterization of Pseudomonas aeruginosa fatty acid profiles in biofilms and batch planktonic cultures

The fatty acid composition of Pseudomonas aeruginosa PAO1 was compared between biofilm and batch planktonic cultures. Strain PAO1 biofilms were able to maintain a consistent fatty acid profile for up to 6 days, whereas strain PAO1 batch planktonic cultures showed a gradual loss of cis-monounsaturated fatty acids over 4 days. Biofilms exhibited a greater proportion of hydroxy fatty acids but a lower proportion of both cyclopropane fatty acids and saturated fatty acids (SAFAs). SAFAs with >=16 carbons, in particular, decreased in biofilms when compared with that in batch planktonic cultures. A reduced proportion of SAFAs and a decline in overall fatty acid chain length indicate more fluidic biophysical properties for cell membranes of P. aeruginosa in biofilms. Separating the biofilms into 2 partitions and comparing their fatty acid compositions revealed additional trends that were not observed in the whole biofilm: the shear-nonremovable layer consistently showed greater proportions of hydroxy fatty acid than the bulk liquid + shear-removable portion of the biofilm. The shear-nonremovable portion demonstrated a relatively immediate decline in the proportion of monounsaturated fatty acids between days 2 and 4; which was offset by an increase in the proportion of cyclopropane fatty acids, specifically 19:0cyc(11,12). Simultaneously, the shear-removable portion of the biofilm showed an increase in the proportion of trans-monounsaturated fatty acids and cyclopropane fatty acids.     

Dynamics of a pasture soil microbial community after deposition of cattle urine amended with [13C]urea

Within grazed pastures, urine patches are hot spots of nitrogen turnover, since dietary N surpluses are excreted mainly as urea in the urine. This short-term experiment investigated 13C uptake in microbial lipids after simulated deposition of cattle urine at 10.0 and 17.1 g of urea C m(-2). Confined field plots without or with cattle urine amendment were sampled after 4 and 14 days, and soil from 0- to 5-cm and 10- to 20-cm depths was analyzed for content and composition of phospholipid fatty acids (PLFAs) and for the distribution of urea-derived 13C among individual PLFAs. Carbon dioxide emissions were quantified, and the contributions derived from urea were assessed. Initial changes in PLFA composition were greater at the lower level of urea, as revealed by a principal-component analysis. At the higher urea level, osmotic stress was indicated by the dynamics of cyclopropane fatty acids and branched-chain fatty acids. Incorporation of 13C from [13C]urea was low but significant, and the largest amounts of urea-derived C were found in common fatty acids (i.e., 16:0, 16:1omega7c, and 18:1omega7) that would be consistent with growth of typical NH4(+)-oxidizing (Nitrosomonas) and NO2(-)-oxidizing (Nitrobacter) bacteria. Surprisingly, a 20 per thousand depletion of 13C in the cyclopropane fatty acid cy17:0 was observed after 4 days, which was replaced by a 10 to 20 per thousand depletion of that in cy19:0 after 14 days. Possible reasons for this pattern are discussed. Autotrophic nitrifiers could not be implicated in urea hydrolysis to any large extent, but PLFA dynamics and the incorporation of urea-derived 13C in PLFAs indicated a response of nitrifiers which differed between the two urea concentrations.     

Hyperthermic sensitivity and growth stage in Escherichia coli

Hyperthermic sensitivities of Escherichia coli B/r and Bs-1 were determined for lag-, midlog-, and stationary-phase cells at 47, 48, and 49 degrees C. In both strains midlog-phase cells were strikingly more heat sensitive (100-fold greater killing after 4 h at 48 degrees C) than stationary-phase cells, with intermediate sensitivity for lag-phase cells. In contrast to the reported difference in the radiation sensitivity between these two strains, very little difference in heat sensitivity was seen. Patterns of fatty acid composition of both strains were very similar at each phase of growth. From midlog to stationary phase, 16:1 and 18:1 unsaturated fatty acids decrease from 16 and 30% to 0.5 and 3%, respectively, while the C17 and C19 cyclopropane fatty acids increase from 7 and 3% to 22 and 25%, respectively. Concomitant with these changes in fatty acid composition, substantially higher membrane microviscosity values were recorded for stationary-phase cells. Total membrane microviscosity was positively associated with the C17 and C19 cyclopropane fatty acid composition and with cell survival following hyperthermia. In contrast to hyperthermic sensitivity, radiation survival differences between B/r and Bs-1 are little affected by growth stage. We propose that these results are consistent with a critical influence of membrane lipids on cellular hyperthermic sensitivity and further that the target sites for radiation and hyperthermia are different in these cells.     

Temperature- and growth-phase-regulated changes in lipid fatty acid structures of psychrotolerant groundwater Proteobacteria

Cellular fatty acid compositions of five psychrotolerant groundwater isolates representing alpha- and beta-Proteobacteria were studied at temperatures ranging from 8 to 25 degrees C. Unsaturation of straight-chain fatty acids was the most common response to decreasing temperature and was detected in four of the isolates. On solid media, decrease of temperature resulted in a decrease of cyclopropane fatty acids in beta-proteobacterial isolates. The formation of cyclopropane fatty acids depended, however, to a greater extent on the growth phase than the temperature and increased drastically as the cells entered stationary phase. The alpha-proteobacterial isolates contained a branched C(19:1) fatty acid. The formation of the branched C(19:1) increased during growth in the same way as the cyclopropane fatty acids in beta-proteobacterial strains, indicating possibly an analogous formation of the branched fatty acid by methylation of the 18:1 fatty acid. Sphingomonas sp. K6 possessed a novel temperature-induced modification of lipid fatty acids. As temperature decreased from 25 to 8 degrees C, the fatty acid composition shifted from predominantly even-carbon fatty acids to odd-carbon fatty acids. The results show completely different fatty acid modifications in two strains of the same genus Sphingomonas.     

培养条件对海洋假单胞菌脂肪酸的影响

研究了不同温度条件下一株海绵附生假单胞菌(Pseudomonassp.)在不同碳源培养基中的生长情况及脂肪酸变化.结果表明,该海洋菌生长最适温度为30℃,在以淀粉作为外加碳源的培养基中生长最好;实验菌含13种脂肪酸,主要是c16:1(n7)、c15:0、c16:0、c17:0、c18:1(n6)、c18:1(n9)、9,10cp c17:0和其同分异构体.在30℃温度条件下,不饱和脂肪酸的相对含量急剧减少.在有外加碳源(葡萄糖和淀粉)的培养基中生长的细菌,奇数脂肪酸和环丙基脂肪酸含量远比未外加碳源的低.聚类分析结果表明,两种环境因子中,温度比碳源的影响更明显.     

Dependence of arbuscular-mycorrhizal fungi on their plant host for palmitic acid synthesis

Lipids are the major form of carbon storage in arbuscular-mycorrhizal fungi. We studied fatty acid synthesis by Glomus intraradices and Gigaspora rosea. [(14)C]Acetate and [(14)C]sucrose were incorporated into a synthetic culture medium to test fatty acid synthetic ability in germinating spores (G. intraradices and G. rosea), mycorrhized carrot roots, and extraradical fungal mycelium (G. intraradices). Germinating spores and extraradical hyphae could not synthesize 16-carbon fatty acids but could elongate and desaturate fatty acids already present. The growth stimulation of germinating spores by root exudates did not stimulate fatty acid synthesis. 16-Carbon fatty acids (16:0 and 16:1) were synthesized only by the fungi in the mycorrhized roots. Our data strongly suggest that the fatty acid synthase activity of arbuscular-mycorrhizal fungi is expressed exclusively in the intraradical mycelium and indicate that fatty acid metabolism may play a major role in the obligate biotrophism of arbuscular-mycorrhizal fungi.     

Influence of stringent and relaxed response on excretion of recombinant proteins and fatty acid composition in Escherichia coli

In contrast to stringent (relA⁺) cells of Escherichia coli, relaxed (relA) cells excreted recombinant proteins (-lactamase, interferon 1) into the culture medium during amino acid limitation. Comparative analyses of overall fatty acid composition in relA⁺ cells and relA cells were performed and revealed that, in wild-type cells, drastic alterations occurred during the stringent response. The portion of saturated fatty acids (C16:0) and the fractions of cyclopropane fatty acids (C17_cyc and C19_cyc) increased whereas the portions of unsaturated fatty acids (C16:1 and C18:1) decreased. In cells of the relaxed mutant, no significant changes in the overall composition of the fatty acids were observed after the onset amino acid limitation. These results indicate that a change in fatty acid composition of membrane lipids after starvation of cells may be responsible for the prevention of loss of cellular proteins into the culture medium in stringent controlled cells of Escherichia coli.     

Fatty Acid Composition of Pseudomonas syringae pv. savastanoi

Over 85% of total cellular fatty acids of 30 strains of P. syringae pv. savastanoi, grown for one day at 28 °C on King's medium B (KB) agar, were 12:0 (5.0%), 16:0 (27.5%), 16:1 (36.7%) and 18:1 (16.8%). Three hydroxy-substituted fatty acids comprised 7.2% of the total and 22 other minor components, each occurring at concentrations of less than 1%, comprised an additional 4%. Three percent were unidentified components. Cells grown for 3 and 6 days on KB agar contained lower concentrations of the unsaturated 16:1 (30.4 and 21.1%, respectively), and higher concentrations of branched-chain and cyclopropane fatty acids than one-day old cells. No consistent differences in fatty acid composition could be detected between virulent and avirulent strains, nor between pv. savastanoi and other pathovars of P. syringae. However, when cells were grown on a chemically-defined medium for 6 days, concentrations of 16:0 and a tentatively-identified 17-carbon hydroxy fatty acid were higher, and those of 12:0 and 16:1 were lower in strains from Fraxinus than from Olea. P. fluorescens (7 strains) and P. viridiflava (6 strains) could be differentiated from each other but not from P. syringae.     

Fatty acid, compatible solute and pigment composition of obligately chemolithoautotrophic alkaliphilic sulfur-oxidizing bacteria from soda lakes

Salt adaptation in chemolithotrophic alkaliphilic sulfur-oxidizing strains belonging to genera Thioalkalimicrobium and Thioalkalivibrio has been studied by determination of salt-dependent changes in fatty acid and compatible solute composition. In both alkaliphilic groups, represented by the low salt-tolerant Thioalkalimicrobium aerophilum strain AL 3T and the extremely salt-tolerant Thioalkalivibrio versutus strain ALJ 15, unsaturated fatty acids predominate over saturated fatty acids. In strain AL 3T, C18:1, C16:0 and C16:1 were the dominant fatty acids. In strain ALJ 15, the concentrations of C18:1 and C19cyclo were salt-regulated in an inverse proportional relationship, suggesting the stimulation of cyclopropyl-synthetase activity. Squalene has been found in substantial amounts only in strain ALJ 15. Ectoine and glycine betaine were found to be the main osmolytes in Thioalkalimicrobium aerophilum and Thioalkalivibrio versutus, respectively. The production of ectoine and glycine betaine was positively correlated with the salt concentration in the growth medium. A novel type of membrane-bound yellow pigments was uniformly detected in the extremely salt-tolerant strains of Thioalkalivibrio with a backbone consisting of C15-polyene, whose specific concentration correlated with increasing salinity of the growth medium. The results suggest that the mechanisms of haloalkaliphilic adaptation in Thioalkalimicrobium sp. and Thioalkalivibrio sp. involve the production of cyclopropane fatty acids, organic compatible solutes and, possibly specific pigments.     

Analysis of fatty acid composition of Candida species by gas-liquid chromatography using a polar column

The fatty acid composition of representative Candida species was examined by gas-liquid chromatography (GLC) using a polar column. The major fatty acids were C14:0, C16:0, C18:0 saturated, C16:1 and C18:1 monoenoic series, with or without C18 polyunsaturated acids (C18:2 and C18:3). In Torulopsis glabrata and Saccharomyces cerevisiae the C18:2 and C18:3 acids were not found, but the C10:0 and C12:0 acids were detected in S. cerevisiae. These results indicated that the Candida genus could be distinguished from Torulopsis and Saccharomyces genera by GLC analysis of fatty acids. Quantitative differences in the fatty acid composition between cells grown at high temperature (37 degrees C) and low temperature (25 degrees C) were found generally in Candida species, and the amounts of C18 polyunsaturated acids (C18:2 and C18:3) increased in the cells grown at 25 degrees C. Each Candida species showed a characteristic profile in fatty acid composition. Determination of the cellular fatty acid composition in Candida species is likely to be useful for the grouping or chemotaxonomy of newer isolates of Candida species.     

Elongation of C16:0 to C18:0 fatty acids in methylotrophic yeast Hansenula polymorpha CBS 1976 and fatty acid auxotrophic mutants

Fatty acid elongation defective mutant was isolated from the ethyl methanesulfonate treated Hansenula polymorpha based on the growth ability. Using biochemical and genetic approaches, the mutant was characterized. When compared with the fatty acid phenotype of the parental strain, the differences in profile and content of fatty acids in V1 mutant were found. In this V1 mutant, polyunsaturated fatty acids, linoleic and alpha-linolenic acids, could not be detected with a corresponding increase in the content of mono-unsaturated fatty acids. The ratio of C16/C18 fatty acids revealed that the accumulation of C16 fatty acids was increased significantly. The experiments on fatty acid supplementation indicated that the mutant required C18:0 for the proper growth. The results of genetic complementation with the elongase genes of Saccharomyces cerevisiae confirmed that the lesion was occurred at least in the extension of C16:0 to C18:0 of V1. The H. polymorpha mutant obtained in this work will be used as a useful tool for unraveling the pathway of fatty acid synthesis and the role of fatty acids on biological processes.     

Degradation of bacterial cyclopropane acids with boron trihalide reagents

The cellular fatty acid compositions of Pseudomonas diminuta UC 501 and Streptococcus mutans OMZ-61 were compared in samples processed by a saponification-methylation procedure (method S) and in samples processed by a transesterification procedure (method T). All samples were heated in an inert atmosphere of nitrogen. The major acids found in samples of P. diminuta treated by method S included 16:0 (palmitic), 18:1 (octadecenoic) and 19 cyc (19 carbon cyclopropane acid). Those found in samples of S. mutans treated by the same method included 16:0, 18:1. 18:0 (stearic), 20:1 (eicosenoic), 20:0 (eicosanoic), 19 cyc and 21 cyc. When method T was used to process samples of both cultures, the cyc acids were degraded and artifacts were produced. Transesterification with boron trihalide reagents is therefore not recommended for routine analysis of bacterial fatty acids.     

Relationship of Cellular Fatty Acid Composition to Survival of Lactobacillus bulgaricus in Liquid Nitrogen

Concentrated cultures of Lactobacillus bulgaricus were prepared by resuspending cells grown in semisynthetic media in sterile 10% non-fat milk solids. The concentrated cultures were frozen in liquid nitrogen for 24 h. The cell suspensions exhibited decreased viability after storage, and the amount of death varied among the different strains tested. Storage stability of all strains examined was improved by supplementing the growth medium with sodium oleate. Radioisotopes were used to study the fate of sodium oleate with L. bulgaricus NCS1. [1-(14)C]sodium oleate was incorporated solely into the lipid portion of the cells, including both neutral and polar lipids. The fatty acid composition of L. bulgaricus NCS1, NCS2, NCS3, and NCS4 grown with and without sodium oleate was studied. The major fatty acids of strains NCS1, NCS2, and NCS3 grown without sodium oleate were dodecanoic, tetradecanoic, hexadecanoic, hexadecenoic, and octadecenoic acids. In addition to these, strain NCS4 contained C(19) cyclopropane fatty acid. The major fatty acids of all strains grown with sodium oleate were tetradecanoic, hexadecanoic, hexadecenoic, octadecenoic, and C(19) cyclopropane fatty acids. All strains grown in broth containing sodium oleate contained larger amounts of octadecenoic and C(19) cyclopropane fatty acid, and less saturated fatty acids than when grown without sodium oleate. Statistical analyses indicated that C(19) cyclopropane fatty acid was most closely related to stability of the lactobacilli in liquid nitrogen. A negative regression line that was significant at P < 0.001 was obtained when the cellular content of this fatty acid was plotted against death.     

The effect of cold, acid and ethanol shocks on synthesis of membrane fatty acid, freeze-drying survival and malolactic activity of Oenococcus oeni

The effects of stress shocks on the freeze-drying viability, malolactic activity and membrane fatty acid composition of the Oenococcus oeni SD-2a cells were studied. O. oeni SD-2a cells after 2 h of stress exposure exhibited better freeze-drying viability and malolactic fermentation ability. A decrease in unsaturated fatty acids/saturated fatty acids (UFA/SFA) ratio and in the C18:1 relative concentration, and an increase in cyclopropane fatty acids (CFA) content mainly due to the increase in C19cyc11 relative concentration were observed in all stress shocked cells. There was a significant negative correlation between C19cyc11 and C18:lcis11, C16:0 in all stress shocks. The freeze-drying viability exhibited a significant positive correlation with the levels of C19cyc11 in cold and acid shocks. The only significant positive correlation between the ability of O. oeni SD-2a to conduct malic acid degradation and membrane composition existed with C14:0 in ethanol shocks. In general, freeze-drying viabilities were maximum for cells with low UFA/SFA ratio and high CFA levels, and, consequently, with low membrane fluidity. Moreover, CFA formation played a major role in protecting stress shocked cells from lyophilization. However, changes observed in membrane fatty acid composition are not enough to explain the greater freeze-drying viability of cells shocked at 8% ethanol. Thus, other mechanisms could be responsible for this increase in the bacterial resistance to lyophilization.     

Structure and composition of intracytoplasmic membranes of Ectothiorhodospira mobilis

The lamellar membrane stacks of Ectothiorhodospira mobilis were isolated and purified by a combination of lysozyme and osmotic shock treatment, followed by differential and density gradient centrifugation. Preparations of lamellar membranes were enriched at least 2.4-fold in the ratio of bacteriochlorophyll a to protein.Thin-sectioning, negative staining, platinumcarbon shadowing and freeze-etching were used to study the architecture of the membrane units. Both platinum-carbon shadowing and freeze-etching showed the outer surfaces of the isolated lamellar membrane stacks to be relatively smooth. Particles averaging 7 nm in diameter were seen on several faces following freeze-ctching.Non-polar amino acids amounted to 60% of the total amino acid composition. Lipids constituted 32% of the membrane dry weight. Phosphatidyl ethanolamine and diphosphatidyl glycerol were the major phospholipids. Fatty acids of 10–15 carbons represented a small fraction of both membrane and whole cell fatty acids. Monoenes constituted 36% of the total membrane fatty acids and 38.4% of the total whole cell fatty acids. The major fatty acids of both whole cells and purified membranes were C16:0, C18:1 and cyclopropane C19:0.