Fatty Acid Composition In Response Research Articles

Carvacrol alters the membrane phospholipids in erythromycin-resistant Streptococcus pyogenes

BackgroundPhospholipids are significant constituents of bacterial membranes. Bacteria can alter their cytoplasmic membrane fatty acid composition in response to changing environmental stress conditions. Carvacrol, a mono-terpenoid phenol, has excellent antibacterial properties against Streptococcus pyogenes. PurposeThis study examined modifications of the membrane phospholipid composition in the presence of sublethal carvacrol concentrations using erythromycin-resistant S. pyogenes. MethodsThe cell membrane isolates (CMIs) were prepared from S. pyogenes strain Spy 1558, erm. The ultrastructural morphology was studied using transmission electron microscopy (TEM). Carvacrol-treated CMIs were analyzed for fluidity changes using fluorescence-anisotropy. Changes in membrane lipid composition were assessed using ultra-high-performance liquid chromatography-mass spectrometry (UHPLC-MS/MS). ResultsFluidity of the bacterial membrane increased time-dependently when exposed to carvacrol. The CMI isolated from cells treated with carvacrol showed a change in cardiolipins (CL), phosphatidylglycerol (PG), and phosphatidylethanolamine (PE) percentages compared to the untreated control. ConclusionCarvacrol induces modulation of specific membrane phospholipid and fatty acid composition of S. pyogenes. Further investigations are necessary to understand how fatty acid and phospholipid biosynthesis can be influenced by carvacrol.

Liver phospholipid fatty acid composition in response to chronic high-fat diets

Liver phospholipid fatty acid composition depends on the dietary lipid intake and the efficiency of hepatic enzymatic activity. Our study aimed to simultaneously investigate the liver phospholipid fatty acid composition in response to chronic linseed, palm, or sunflower oil diets. We used adult female C57/BL6 mice and randomly divided them into control and three groups treated with 25 % dietary oils. Prior to treatment, we analyzed the fatty acid profiles in dietary oils and hepatocytes and, after 100 days, the fatty acid composition in the liver using gas-liquid chromatography. Linseed oil treatment elevated alpha-linolenic, eicosapentaenoic, and docosapentaenoic acids and reduced arachidonic and docosatetraenoic acids, consequently lowering the n-6/n-3 ratio. Palm oil treatment increased linoleic acid and decreased docosahexaenoic acid, contributing to an elevated n-6/n-3 ratio. Sunflower oil treatment elevated total monounsaturated fatty acids by increasing palmitoleic, oleic, and vaccenic acids. The estimated activity of Δ9 desaturase was significantly elevated in the sunflower oil group, while Δ5 desaturase was the highest, and Δ6 desaturase was the lowest after the linseed oil diet. Our findings demonstrate that chronic consumption of linseed, palm, or sunflower oil alters the distribution of liver phospholipid fatty acids differently. Sunflower oil diet elevated total monounsaturated fatty acids, proposing potential benefits for liver tissue health. Considering these outcomes, a substantial recommendation emerges to elevate linseed oil intake, recognized as the principal ALA source, thereby aiding in reducing the n-6/n-3 ratio. Moreover, modifying dietary habits to incorporate specific vegetable oils in daily consumption could substantially enhance overall health.

Thylakoid fatty acid composition and response to short-term cold and heat stress in high-latitude Symbiodiniaceae

AbstractCoral reefs are restricted to warm waters, but are increasingly threatened by coral bleaching induced by sustained high sea surface temperatures. Coral endosymbiont thermal resilience has been proposed to depend, at least in part, on the lipid composition of their thylakoid membranes, which influences photosynthetic performance under sub- and super-optimal thermal conditions in photosynthetic organisms. Dinoflagellate symbionts of high-latitude coral reefs experience large seasonal changes in temperature, requiring a wide range of thermal tolerance, and so the thermal responses of their membrane lipids are of particular interest. Using gas chromatography–mass spectrometry, we investigated the composition and response to high- and low-temperature stress of thylakoid fatty acids of dinoflagellate symbionts isolated from corals of Lord Howe Island, the world’s southernmost coral reef. We detected genotype-specific differences in the quality of thylakoid fatty acids of two Cladocopium ITS2 consortia/genotypes, C100/118 and C111*, common local symbionts of the corals Pocillopora damicornis and Porites heronensis. The capability to adjust thylakoid fatty acid composition in response to temperature differed between distinct Cladocopium genotypes, and between the same Cladocopium consortium (C100/118) in the same coral species from different locations. Fatty acid adjustments were highly similar in response to short-term cold and heat stresses, with substantial increases in long-chain polyunsaturated fatty acids and a corresponding increase in the ratio of unsaturated to saturated fatty acids, but these changes did not correlate with the quantum yield of photosystem II. The response of thylakoid fatty acid composition to changes in temperature was a function of symbiont genotype, coral host species and, potentially, environmental history. Our data suggest the existence of common responses to high- and low-temperature stresses and that thylakoid fatty acid saturation is an unreliable predictor of photosystem efficiency under thermal stress in dinoflagellate symbionts.

Comparative Proteomics of Meat Spoilage Bacteria Predicts Drivers for Their Coexistence on Modified Atmosphere Packaged Meat

Besides intrinsic and extrinsic factors such as antagonism for organic substrates or temperature, the storage atmosphere of meat has a high influence on the development of its initial microbiota. Specific modified atmospheres (MAs) selectively suppress growth of aerobic and anaerobic bacteria, thus reshaping the initial microbiota. As some microorganisms are more tolerant to MA, they overgrow competitors and produce metabolites that cause rejection of the product. In order to elucidate responses to different MA by means of metabolic adaptation and competition for organic substrates on meat, the typical representative meat spoilage bacteria Brochothrix (B.) thermosphacta TMW2.2101 and four lactic acid bacteria Carnobacterium (C.) divergens TMW2.1577, C. maltaromaticum TMW2.1581, Leuconostoc (L.) gelidum subsp. gelidum TMW2.1618 and L. gelidum subsp. gasicomitatum TMW2.1619 were chosen. Bacteria were grown in sterile glass bottles filled with a meat simulation medium, which was aerated constantly with either air, 100%_N2, 30%_CO2/70%_O2 or 30%_CO2/70%_N2. Growth of bacteria during incubation at 25°C and stirring at 120 rpm was monitored over 48 h and a label-free quantitative mass spectrometric approach was employed to determine changes within the bacterial proteomes in response to oxygen and carbon dioxide. Both Leuconostoc subsp. were intrinsically tolerant to MA, exhibiting no proteomic regulation of enzymes, whereas the other species provide a set of metabolic adaptation mechanism, enabling higher resistance to the detrimental effects of MA. Those mechanisms comprise: enhanced oxidative stress reduction, adjustment of the pyruvate metabolism and catabolic oxygen consumption in response to oxygen and intracellular pH homeostasis, maintenance of osmotic balance and alteration of the fatty acid composition in response to carbon dioxide. We further evaluated the potential of industrial used MA to inhibit specific bacterial spoilage. No bacterial inhibition is predicted for 30%_CO2/70%_O2 for the analyzed species, whereas 30%_CO2/70%_N2 predictively inhibits C. divergens TMW21577 and B. thermosphacta TMW2.2101. Furthermore, species-specific metabolic pathways enabling different and preferential carbon source utilization were identified, which enable non-competitive coexistence of respective bacteria on meat, resulting in synergistic spoilage. In conclusion, this study gives mechanistically explanations of their acknowledged status as typical spoilage organisms on MAP meats.

Consequences of oxidative damage and mitochondrial dysfunction on the fatty acid profile of muscle of Indian Major Carps considering metal toxicity

Current study aims to find interrelation between mitochondrial enzyme function and fatty acid profile in fish muscle and role of antioxidant agents to maintain their balance in response to metal accumulation. Fishes (Labeo rohita, Catla catla, Cirrhinus cirrhosus) were collected from two sites (Nalban Bheri and Diamond Harbour, India). Concentrations of metals (lead, cadmium, copper, nickel, zinc), enzymatic and non-enzymatic antioxidant activity (malondialdehyde, superoxide dismutase, catalase, glutathione reductase, glutathione peroxidase, glutathione S-transferase), muscle enzyme activity (acetylcholinesterase, succinate dehydrogenase, lactate dehydrogenase, Ca2+ATPase, AMP-deaminase, lipoamide reductase, cytochrome C oxidase, aldolase) and fatty acid composition in muscle tissues were analyzed. Metal concentrations were significantly higher (P < 0.05) in fish muscles from Nalban compared to those in Diamond Harbour. Increased activity of antioxidant enzymes was noted with diminished mitochondrial enzymes activity and altered fatty acid composition in response to higher metal accumulation. Higher metal concentration in fish muscle of Nalban seems to significantly (P < 0.05) affect poly and monounsaturated fatty acid content, possibly due to oxidative damage and accumulation of hazardous reactive oxygen species (ROS) molecules. Changes in fatty acid contents following metal accumulation were observed to be species specific. Current study is the first correlative study to illuminate the level of oxidative damage and possible consequences on muscle cellular integrity, mitochondrial functionality and flesh quality against bioaccumulation of different metals in carps. Future studies are needed to quantify the relative contributions of enzymatic and low-molecular-mass antioxidants in protecting mitochondrial function and maintenance of proper fatty acid oxidation during acclimation to long term metal exposure.

Effect of Level of Spirulina Supplementation on the Fatty Acid Compositions of Adipose, Muscle, Heart, Kidney and Liver Tissues in Australian Dual-Purpose Lambs

Abstract This study investigated the effect of level of Spirulina supplementation on the fatty acid (FA ) compositions of subcutaneous adipose, longissimus dorsi muscle, kidney, heart, and liver tissues in purebred and crossbred Australian Merino sheep. Forty-eight lambs sired by Black Suffolk, White Suffolk, Dorset and Merino rams were assigned into 4 treatment groups of daily Spirulina supplementation levels per lamb of 0 mL (control), 50 mL (low), 100 mL (medium) and 200 mL (high) referred to as 0, 5, 10 and 20% groups. The lambs were slaughtered after 9 weeks of supplementation and heart, kidney, adipose, liver and muscle tissue samples were collected. The results demonstrated significant variations in growth and body conformation traits and tissue and organ FA composition in response to the Spirulina supplementation. The medium-level Spirulina treatment group increased the ω-3 and ω-6 polyunsaturated fatty acid (PUFA ) composition in all tissues and organs significantly. The results suggest the use of medium level (100 mL/head/day) of Spirulina supplementation in order to increase lamb production with more ω-3 and ω-6 PUFA and therefore higher nutritional meat quality.

The influence of cadmium chloride and hyperthermia on the fatty acid composition of high aquatic plants from Angara River

Water is the basic component of all living organisms and the biosphere. The intensification of using water in the industrial, agricultural and domestic consumption leads to an increased anthropogenic impact on water ecosystems. High aquatic plants are the most important component of aquatic ecosystems. They take part in the process of exchange of nutrients in self-purification of water, can accumulate and transform organic and inorganic pollutants. Aquatic plants are considered and used as sites for monitoring ecological status of water bodies. In this study we investigated the fatty acid composition of higher aquatic plants from Angara River under the influence of hyperthermia 30 °C, and cadmium chlo­ride 100 mg/l. Macrophytes Elodea canadensis Michx. and Myrio­phyllum spicatum L. were gathered at a high flow of Angara River. After cultivation in the laboratory conditions the plants from experimental group were replaced in a solution of cadmium chloride (100 mg/l) during 24 and 48 h. In another experiment the plants were replaced in distilled water, 30 °C heated, and incubated during 24 or 48 h. Lipids were extracted with mixture of chloroform: methanol (2:1). Analysis of fatty acids composition was carried out in form of methyl ethers by the method of chromato-mass-spectrometry. The changes of the fatty acid composition in response to hyperthermia and cadmium chloride were found. The differences in the fatty acid composition changes of the studied species were shown after 24 and 48 h of exposure. Differences in the metabolism of fatty acids should be considered for the development of methods of biomonitoring and bioassay.

Isolation of Butanol- and Isobutanol-Tolerant Bacteria and Physiological Characterization of Their Butanol Tolerance

Despite their importance as a biofuel production platform, only a very limited number of butanol-tolerant bacteria have been identified thus far. Here, we extensively explored butanol- and isobutanol-tolerant bacteria from various environmental samples. A total of 16 aerobic and anaerobic bacteria that could tolerate greater than 2.0% (vol/vol) butanol and isobutanol were isolated. A 16S rRNA gene sequencing analysis revealed that the isolates were phylogenetically distributed over at least nine genera: Bacillus, Lysinibacillus, Rummeliibacillus, Brevibacillus, Coprothermobacter, Caloribacterium, Enterococcus, Hydrogenoanaerobacterium, and Cellulosimicrobium, within the phyla Firmicutes and Actinobacteria. Ten of the isolates were phylogenetically distinct from previously identified butanol-tolerant bacteria. Two relatively highly butanol-tolerant strains CM4A (aerobe) and GK12 (obligate anaerobe) were characterized further. Both strains changed their membrane fatty acid composition in response to butanol exposure, i.e., CM4A and GK12 exhibited increased saturated and cyclopropane fatty acids (CFAs) and long-chain fatty acids, respectively, which may serve to maintain membrane fluidity. The gene (cfa) encoding CFA synthase was cloned from strain CM4A and expressed in Escherichia coli. The recombinant E. coli showed relatively higher butanol and isobutanol tolerance than E. coli without the cfa gene, suggesting that cfa can confer solvent tolerance. The exposure of strain GK12 to butanol by consecutive passages even enhanced the growth rate, indicating that yet-unknown mechanisms may also contribute to solvent tolerance. Taken together, the results demonstrate that a wide variety of butanol- and isobutanol-tolerant bacteria that can grow in 2.0% butanol exist in the environment and have various strategies to maintain structural integrity against detrimental solvents.

Unexpected shifts in fatty acid composition in response to diet in a common littoral amphipod

To determine whether fatty acid (FA) profiles are a useful biomarker to trace the flow of material in a coastal food web, we fed the sandhopper Bellor - chestia quoyana specific seaweed diets, each with a contrasting FA profile including Durvillaea antarctica (Phaeophyta), Ecklonia radiata (Phaeophyta) or Ulva sp. (Chlorophyta). We then compared changes in FA composition in relation to diet for this sandhopper. After 12 d, sandhoppers from each treatment had distinct FA profiles, particularly with respect to polyunsaturated FAs (PUFAs); however, increases in specific FAs did not relate to those FAs that were abundant in their diet. For example, sandhoppers fed PUFA-deficient Ulva sp. exhibited a relative increase in PUFAs. The E. radiata and Ulva sp. diets both caused significant shifts in sandhopper FA composition over the course of the experiment. In order to follow the assimilation of carbon and FAs, sandhoppers were fed natural or 13C-enhanced E. radiata or Ulva sp., and changes to the δ13C of individual FAs were measured over time. Turnover of the most abundant FAs, 16:0 and 18:1ω9, was higher for sandhoppers fed E. radiata than for those fed Ulva sp. Comparisons between bulk tissue δ13C and δ13C of individual FAs were consistent with sandhoppers modifying the turnover rate of FA in response to diet. These findings suggest that there is no consistent relationship between the FA compositions of green and brown seaweeds and that of the sandhopper B. quoyana. We caution that community-level application of FAs as a dietary biomarker tool must be accompanied by controlled experiments incorporating key species of relevance.

Dietary Docosahexaenoic Acid (22:6) Incorporates into Cardiolipin at the Expense of Linoleic Acid (18:2): Analysis and Potential Implications

Cardiolipin is a signature phospholipid of major functional significance in mitochondria. In heart mitochondria the fatty acid composition of cardiolipin is commonly viewed as highly regulated due to its high levels of linoleic acid (18:2n − 6) and the dominant presence of a 4×18:2 molecular species. However, analysis of data from a comprehensive compilation of studies reporting changes in fatty acid composition of cardiolipin in heart and liver mitochondria in response to dietary fat shows that, in heart the accrual of 18:2 into cardiolipin conforms strongly to its dietary availability at up to 20% of total dietary fatty acid and thereafter is regulated. In liver, no dietary conformer trend is apparent for 18:2 with regulated lower levels across the dietary range for 18:2. When 18:2 and docosahexaenoic acid (22:6n − 3) are present in the same diet, 22:6 is incorporated into cardiolipin of heart and liver at the expense of 18:2 when 22:6 is up to ~20% and 10% of total dietary fatty acid respectively. Changes in fatty acid composition in response to dietary fat are also compared for the two other main mitochondrial phospholipids, phosphatidylcholine and phosphatidylethanolamine, and the potential consequences of replacement of 18:2 with 22:6 in cardiolipin are discussed.

Milk fat depression induced by dietary marine algae in dairy ewes: Persistency of milk fatty acid composition and animal performance responses

Addition of marine algae (MA) to the diet of dairy ruminants has proven to be an effective strategy to enhance the milk content of some bioactive lipids, but it has also been associated with the syndrome of milk fat depression. Little is known, however, about the persistency of the response to dietary MA in sheep. Based on previous experiments with dairy ewes fed sunflower oil plus MA, it was hypothesized that the response might be mediated by time-dependent adaptations of the rumen microbiota, which could be evaluated indirectly through milk fatty acid (FA) profiles. Animal performance and milk FA composition in response to MA in the diet were studied using 36 Assaf ewes distributed in 6 lots and allocated to 2 treatments (3 lots/treatment) consisting of a total mixed ration (40:60 forage:concentrate ratio) supplemented with 25g of sunflower oil (SO)/kg of dry matter plus 0 (SO; control diet) or 8g of MA/kg of dry matter (SOMA diet). Milk production and composition, including FA profile, were analyzed on d 0, 6, 12, 18, 24, 34, 44, and 54 of treatment. Diet supplementation with MA did not affect milk yield but did decrease milk fat content. Differences in the latter were detected from d 18 onward and reached −17% at the end of the experiment (i.e., on d 54). Compared with the control diet, the SOMA diet caused a reduction in milk 18:0 and its desaturation product (cis-9 18:1) that lasted for the whole experimental period. This decrease, together with the progressive increase in some putative fat synthesis inhibitors, especially trans-10 18:1, was related to the persistency of milk fat depression in lactating ewes fed MA. Additionally, inclusion of MA in the diet enhanced the milk content of trans-11 18:1, cis-9,trans-11 18:2, and C20–22 n-3 polyunsaturated FA, mainly 22:6 n-3. Overall, the persistency of the responses observed suggests that the ruminal microbiota did not adapt to the dietary supply of very long chain n-3 polyunsaturated fatty acids.

Caecum odd‐numbered and branched‐chain fatty acid composition in response to dietary changes in fattening rabbits

The study aimed to describe the interactions between nutrition and caecal bacteria abundance using odd-numbered and branched-chain fatty acids (OBCFA). Following a 2 × 2 factorial design, 47 rabbits were fed diets with two levels of digestible fibre (DF, 180 vs. 260 g/kg DM) supplemented with soybean oil (SO, 20 g/kg) or not. At 77 days of age, fatty acid (FA) composition was determined in caecal contents. The microbial origin of OBCFA vs. dietary FA in caecal contents was illustrated by clustering of these FA in the loading plots of principal component analysis. The contribution of odd-numbered FA in the OBCFA pattern was increased (p < 0.05) for high DF diets, whereas that of branched-chain FA decreased (p < 0.05), indicating potential shifts in the relative abundance of Gram-negative and Gram-positive fibrolytic bacteria respectively. Soybean oil reduced the relative importance of OBCFA (p < 0.001) in total microbial FA; however, its effects appeared to depend on the readily available fermentable substrate, as indicated by the DF × SO interactions (p < 0.001). In conclusion, OBCFA may be potentially used as markers of caecum function, but further detailed studies are necessary to validate their use as diagnostic tools in rabbit nutrition.

Seasonal changes in fatty acid composition of Eysarcoris inconspicuous (Herrich-Schaffer, 1844) (Heteroptera: Pentatomidae) adults

1 * Summary The goal of the study was to investigate the role of phospholipid and triacylglycerol fatty acid compositional changes in Eysarcoris inconspicuous (Herrich- Schaffer, 1844) (Heteroptera: Pentatomidae) with respect to seasonal changes. E. inconspicuous adults were collected from Diyarbakir, Turkey in 2007-2008. The fatty acid compositions of phospholipid and triacylglycerol fractions that were extracted from whole-body of adult E. inconspicuous were isolated and analyzed using gas chromatography and gas chromatography-mass spectrometry. Qualitative analysis has revealed the presence of 15 fatty acids during most of the months. The major components were C16 and C18 saturated and unsaturated components which are ubiquitous in most animal species. In addition to these components, three odd-chain (C13:0), (C15:0), (C17:0), and prostaglandin precursor fatty acids were found. The fatty acid profiles of phospholipids and triacylglycerols have some diferences. In contrast to triacylglycerol fraction, linolenic acid and C20 polyunsaturated fatty acids increased during autumn and winter in phospholipid fraction were detected. The unsaturated fatty acid to saturated fatty acid ratio significantly increased in both fractions but the increase was dramatic in phospholipid fraction during autumn, and reaches its maximum level in january and february, when outdoor temperatures are low. Thus, temperature seems to play an important role in seasonal variation of lipid metabolism of E. inconspicuous. Preventing cellular damage due to low temperatures is a major challenge for insects. These findings indicate that E. inconspicuous can modify its fatty acid composition in response to changes in environmental conditions.

Maximized PUFA measurements improve insight in changes in fatty acid composition in response to temperature

A general mechanism underlying the response of ectotherms to environmental changes often involves changes in fatty acid composition. Theory predicts that a decrease in temperature causes an increase in unsaturation of fatty acids, with an important role for long-chain poly-unsaturated fatty acids (PUFAs). However, PUFAs are particularly unstable and susceptible to peroxidation, hence subtle differences in fatty acid composition can be challenging to detect. We determined the fatty acid composition in springtail (Collembola) in response to two temperatures (5 degrees C and 25 degrees C). First, we tested different sample preparation methods to maximize PUFAs. Treatments consisted of different solvents for primary lipid extraction, mixing with antioxidant, flushing with inert gas, and using different temperature exposures during saponification. Especially slow saponification at low temperature (90 min at 70 degrees C) in combination with replacement of headspace air with nitrogen during saponification and methylation maximized PUFAs for GC analysis. Applying these methods to measure thermal responses in fatty acid composition, the data showed that the (maximized) proportion of C(20) PUFAs increased at low acclimation temperature. However, C(18) PUFAs increased at high acclimation temperature, which is contrary to expectations. Our study illustrates that PUFA levels in lipids may often be underestimated and this may hamper a correct interpretation of differential responses of fatty acid composition.

Variable temperature-related changes in fatty acid composition of bacterial isolates from German Wadden sea sediments representing different bacterial phyla

A total of 24 bacterial strains, including 15 facultative anaerobes and 9 strictly anaerobic sulfate reducers, were isolated under anoxic conditions from an intertidal mudflat of the northwest German coast and analysed for temperature-induced changes in their whole cell fatty acid (FA) patterns. The strains represented 10 different genera within the Alpha, Gamma, Delta and Epsilon subgroups of the Proteobacteria, Firmicutes and Actinobacteria. The strains differed with respect to variation in FA patterns with changing growth temperature. For most strains, decreasing growth temperature resulted in an increase in monounsaturated FAs and a decrease in saturated straight chain FAs, as expected from literature data. Often these changes did not occur gradually over the whole temperature range. Changes in branched FAs, reported to be involved in adaptation to low temperature, increased with decreasing temperature in Bacillus and Shewanella spp., whereas in Desulfovibrio spp. an opposite effect was observed. Only minor changes in chain length or in the ratio of anteiso to iso FAs were observed in the entire set of isolates. Surprisingly, several strains did not show any change at all in FA pattern over the temperature range tested (10–30 °C). Moreover, significant differences in the way the isolates adjusted membrane fluidity to changing temperature were not only found between members of different phyla, but also among strains of a single genus (e.g. Shewanella and Desulfovibrio). The results therefore indicate that there is no unequivocal way as to how bacteria change their membrane FA composition in response to changing temperature and that it is virtually impossible to predict potential changes. Consequently, using the FA composition for taxonomic resolution is problematical.

Milk fatty acid composition in response to reciprocal combinations of sunflower and fish oils in the diet

This study investigated the hypothesis that a high linoleic acid vegetable oil fed in combination with a fish oil ruminal biohydrogenation modifier as a diet supplement would result in higher concentrations of vaccenic and rumenic acids in milk fat versus either fed alone. Four lactating cows were fed legume silage (600 g/kg diet DM) and a lactation concentrate (400 g/kg DM) supplemented with 30 g/kg diet DM of oil in a Latin square design with 3-week experimental periods. Fish oil was proportionately 0, 0.33, 0.67 or 1.0 of the oil supplement, with the balance as sunflower oil. The DM intake decreased linearly (P<0.04) with increasing concentrations of fish oil in the diet. Milk yield and its proportion of protein were unaffected by fish oil intake, whereas the proportion of milk fat increased linearly (P<0.02) with increasing fish oil. Proportions of milk fatty acids from C4 to 16:1 increased linearly (P<0.01) for all fatty acids except 14:1 (NS) as the proportion of fish oil increased. Conversely, 18:0 (0.001), cis-9 18:1 and 18:2 (P<0.01) decreased linearly with increasing fish oil, while trans-11 18:1 and cis-9, trans-11 18:2 were highest at intermediate levels of fish oil. Other identified trans isomers declined as fish oil increased. Arachidonic acid (AA; P<0.001), eicosapentaenoic acid (EPA) and docosapentaenoic acid (DPA; P<0.01) increased linearly in milk fat with increased fish oil feeding, whereas predictions were less robust for docosahexaenoic acid (DHA; P<0.05). Efficiency of transfer of fish oil fatty acids to milk fat, estimated by regressing their milk output on intake, ranged from <0.01 for DHA (P<0.10) to 0.79 for AA (P<0.01). Whereas only 10 mg of DHA/g intake appeared in milk, transfer of EPA was 57 mg/g intake (P<0.04) and for DPA it was 110 mg/g (P<0.01). Supplementing high linoleic vegetable oils with fish oil maximized concentrations of vaccenic and rumenic acids in milk fat, and transfer of eicosanoic fatty acids from diet to milk increased linearly as their intake increased.

Physiological and cellular responses of the 2,4-D degrading bacterium, Burkholderia cepacia YK-2, to the phenoxyherbicides 2,4-D and 2,4,5-T.

Our previous research has demonstrated that novel 43-kDa DnaK and 41-kDa GroEL proteins are synthesized in Burkholderia sp. YK-2 in response to sublethal concentrations of 2,4-D stress [Cho et al. (2000) Curr Microbiol 41:33-38]. In this study, we have extended this work to examine the cellular responses of strain YK-2 to stresses induced in response to the phenoxyherbicides 2,4-D or 2,4,5-T. Strain YK-2 exhibited a more sensitive response to 2,4,5-T stress than to 2,4-D stress, as shown in physiological and morphological changes, suggesting a greater cytotoxic effect of 2,4,5-T. SEM analyses revealed the presence of perforations and irregular rod forms with wrinkled surfaces for cells treated with either herbicide. These irregularities were found more frequently for 2,4,5-T-treated cells than for 2,4-D-treated cells. Analysis of cellular fatty acids showed similar effects in the shifts of total cellular fatty acid composition in response to 2,4-D and 2,4,5-T. Strain YK-2 could degrade 2.25 m M 2,4-D completely during 28 h of incubation with transient production of 2,4-dichlorophenol as a metabolite; however, 2,4,5-T was not catabolized at any of the concentrations tested. BIOLOG and 16S rDNA analyses revealed that strain YK-2 was 98% similar to the Burkholderia cepacia species cluster; therefore, we have designated this strain as B. cepacia YK-2.

Fatty acid membrane composition and activation of glycine-betaine transport in Lactococcus lactis subjected to osmotic stress

Lactococcus lactis subsp. cremoris NCDO763 accumulates glycine-betaine (betaine) when submitted to an osmotic stress with NaCl. Betaine transport activity increases with the extent of the osmotic upshock but also with growth temperature, and supplementation of the medium by Tween-80. Fatty acid analysis of the lipid fraction of L. lactis NCDO763 reveals significant modifications of the fatty acid composition of the membrane when cells are submitted to osmotic stress, high temperature or Tween-80 medium supplementation. The main modification in L. lactis membrane fatty acid composition in response to high osmolality is the increase of Cyclopropane Fatty Acid (CFA) ΔC19:0, whereas Unsaturated/Saturated ratio remains unchanged.

The effect of growth temperature on the phospholipid and fatty acyl compositions of non-proteolytic Clostridium botulinum

A non-proteolytic strain of Clostridium botulinum (NCIB 4270) was found to have a complex lipid composition, comprising five major phosphorus-containing lipids: phosphatidylethanolamine (PE), phosphatidylglycerol (PG), diphosphatidylglycerol (DPG), phosphatidylserine (PS) and a glycophospholipid of unknown structure (GPL), in order of abundance. Changing the growth temperature did not alter the lipid composition either qualitatively or quantitatively. The main fatty acyl components of the lipids are 14:0, 16:0 and 16:1. When the growth temperature was lowered from 37 to 8°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 the 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 acids from 15.9 to 15.3 as the temperature was lowered. The same temperature-dependent changes occurred in the five major lipid classes examined. Despite reports of the presence of plasmalogenic forms of phospholipids (i.e. those lipids which have the acyl chain in the sn-1 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 products or acid methanolysis of total lipid extracts. It is concluded that non-proteolytic C. botulinum lacks plasmalogens, typical of other clostridia, in its membranes and instead modulates its fatty acid composition in response to temperature changes in a manner that is typical of other (non-clostridial) bacteria.

Influence of growth temperature on fatty acids and phospholipids of Steinernema riobravis infective juveniles

1. 1. The entomopathogenic nematode Steinernema riobravis grows and reproduces over a wide temperature range (15, 20, 25, and 30°C) in the insect host Galleria mellonella. 2. 2. The lipid content of S. riobravis varied in amount and composition. PE and PC were the two major constitutive classes of polar lipids whereas triglycerols were the major constitutive classes of neutral lipids. Lipid content of nematodes grown at 15°C was marginally lower than at other growth temperatures. Nematodes accumulated higher proportions of saturated fatty acids when grown at high temperature (30°C). 3. 3. The ability of S. riobravis to adjust its lipid and fatty acid composition in response to growth temperature could contribute to thermal tolerance. We recommend culturing S. riobravis at 25–30°C. At these temperatures more lipids are accumulated which may improve the physiological quality of S. riobravis compared to nematodes produced at lower temperatures (15–20°C). In addition, the growth and development cycle at high growth temperature in the insect cadaver is shorter compared to low temperature, which reduces the cost of mass production if applied in fermentation.