Degree Of Fatty Acid Unsaturation Research Articles

Fatty Acid Unsaturation Degree of Plasma Exosomes in Colorectal Cancer Patients: A Promising Biomarker.

Even though colorectal cancer (CRC) is one of the most preventable cancers, it is currently one of the deadliest. Worryingly, incidence in people <50 years has increased unexpectedly, and for unknown causes, despite the successful implementation of screening programs in the population aged >50 years. Thus, there is a need to improve early diagnosis detection strategies by identifying more precise biomarkers. In this scenario, the analysis of exosomes is given considerable attention. Previously, we demonstrated the exosome lipidome was able to classify CRC cell lines according to their malignancy. Herein, we investigated the use of the lipidome of plasma extracellular vesicles as a potential source of non-invasive biomarkers for CRC. A plasma exosome-enriched fraction was analyzed from patients undergoing colonoscopic procedure. Patients were divided into a healthy group and four pathological groups (patients with hyperplastic polyps; adenomatous polyps; invasive neoplasia (CRC patients); or hereditary non-polyposis CRC. The results showed a shift from 34:1- to 38:4-containing species in the pathological groups. We demonstrate that the ratio Σ34:1-containing species/Σ38:4-containing species has the potential to discriminate between healthy and pathological patients. Altogether, the results reinforce the utility of plasma exosome lipid fingerprint to provide new non-invasive biomarkers in a clinical context.

Fatty acid desaturase activity in mature red blood cells and implications for blood storage quality.

Increases in the red blood cell (RBC) degree of fatty acid desaturation are reported in response to exercise, aging, or diseases associated with systemic oxidant stress. However, no studies have focused on the presence and activity of fatty acid desaturases (FADS) in the mature RBC. Steady state metabolomics and isotope-labeled tracing experiments, immunofluorescence approaches, and pharmacological interventions were used to determine the degree of fatty acid unsaturation, FADS activity as a function of storage, oxidant stress, and G6PD deficiency in human and mouse RBCs. In 250 blood units from the REDS III RBC Omics recalled donor population, we report a storage-dependent accumulation of free mono-, poly-(PUFAs), and highly unsaturated fatty acids (HUFAs), which occur at a faster rate than saturated fatty acid accumulation. Through a combination of immunofluorescence, pharmacological inhibition, tracing experiments with stable isotope-labeled fatty acids, and oxidant challenge with hydrogen peroxide, we demonstrate the presence and redox-sensitive activity of FADS2, FADS1, and FADS5 in the mature RBC. Increases in PUFAs and HUFAs in human and mouse RBCs correlate negatively with storage hemolysis and positively with posttransfusion recovery. Inhibition of these enzymes decreases accumulation of free PUFAs and HUFAs in stored RBCs, concomitant to increases in pyruvate/lactate ratios. Alterations of this ratio in G6PD deficient patients or units supplemented with pyruvate-rich rejuvenation solutions corresponded to decreased PUFA and HUFA accumulation. Fatty acid desaturases are present and active in mature RBCs. Their activity is sensitive to oxidant stress, storage duration, and alterations of the pyruvate/lactate ratio.

RELATIONSHIP BETWEEN MORPHOPHYSIOLOGICAL AND BIOCHEMICAL INDEXISES IN THE LIVER OF TUNDRA VOLES FROM NATUREL SITES WITH INCREASED LEVEL OF RADIOACTIVITY

The correlation analyses was used to assess the relationship between morphophysiological and biochemical parameters in liver of tundra voles from sites differing by level of natural radioactivity at Komi Repablic territory. It is revealed that the body mass males and females from the control and radioactive sites was a higher at the peak of the number of animals than that during the decline phase. In the phase of low abundance the relationship between the animal liver mass and body mass was growing stronger as the habitat radioactivity increases. The linear regression coefficient of this dependence was a 8 times higher in the radium impact sites, which indicates a decrease in the participation of lysoforms in the liver proliferative activity. The level of lipid peroxidation activity and the degree of unsaturated fatty acids in the peak and decline phases affected the severity of the relationship between the minor fractions of lipids metabolism in the liver and morphophysiological parameters of tundra voles. Taken together, the results of our study contribute to understanding of cell mechanisms of tundra vole adaptation to radioactive contamination, and dependence of morphophysiological and biochemical parameters on population heterogeneity and phase of animal abundance.

Visible/Short-wave near-infrared hyperspectral analysis of lipid concentration and fatty acid unsaturation of Scenedesmus obliquus in situ

Microalgae lipid and its degree of fatty acid unsaturation (DU) have the ability to undergo programmatic changes in response to different environmental and culture conditions. A real-time and reliable approach to monitor the change patterns of lipid-accumulation and DU is crucial for microalgal culture and bioprocess control. In this study, a fast visual and nondestructive method based on visible/short-wave near-infrared hyperspectral imaging (V/SNIR HSI) at 400–1000 nm region was developed to investigate the dynamic changes and content distribution of lipids and DU of Scenedesmus obliquus treated by nitrogen-low stress (0.3 g/L NaNO3, NL) and nitrogen-free stress (0 g/L NaNO3, NF). After collecting the average spectra from the region of interests (ROIs), the competitive adaptive reweighted sampling (CARS) algorithm and the successive projection algorithm (SPA) were applied to pick effective wavebands from the spectral data for the establishment of the lipid concentration and DU estimation models including partial least squares regression (PLSR) and multiple linear regression (MLR). The prediction results show the CARS-PLSR (Rp = 0.9762, RMSEp = 0.0143) and CARS-MLR (Rp = 0.9477, RMSEp = 0.5718) performed the best for lipids and DU of S. obliquus, respectively. Based on the optimal models, the spatial distribution of lipid abundance and DU in liquid suspension were visualized, which could be helpful in exploring the dynamic process of lipid synthesis and DU of S. obliquus. The overall results show that V/SNIR HSI is a promising technique for fast and noninvasively monitoring the lipid-accumulation and its characteristics i.e. DU in situ, and is expected to be applied for efficient and high-quality lipid production in microalgae industries.

Endotoxemia is associated with an adverse metabolic profile.

Our aim was to analyze whether endotoxemia, i.e. translocation of LPS to circulation, is reflected in the serum metabolic profile in a general population and in participants with cardiometabolic disorders. We investigated three Finnish cohorts separately and in a meta-analysis (n = 7178), namely population-based FINRISK97, FinnTwin16 consisting of young adult twins, and Parogene, a random cohort of cardiac patients. Endotoxemia was determined as serum LPS activity and metabolome by an NMR platform. Potential effects of body mass index (BMI), smoking, metabolic syndrome (MetS), and coronary heart disease (CHD) status were considered. Endotoxemia was directly associated with concentrations of VLDL, IDL, LDL, and small HDL lipoproteins, VLDL particle diameter, total fatty acids (FA), glycoprotein acetyls (GlycA), aromatic and branched-chain amino acids, and Glc, and inversely associated with concentration of large HDL, diameters of LDL and HDL, as well as unsaturation degree of FAs. Some of these disadvantageous associations were significantly stronger in smokers and subjects with high BMI, but did not differ between participants with different CHD status. In participants with MetS, however, the associations of endotoxemia with FA parameters and GlycA were particularly strong. The metabolic profile in endotoxemia appears highly adverse, involving several inflammatory characters and risk factors for cardiometabolic disorders.

In Vitro and In Vivo Digestibility of Soybean, Fish, and Microalgal Oils, and Their Influences on Fatty Acid Distribution in Tissue Lipid of Mice.

The digestion rates of microalgal (docosahexaenoic acid, DHA, 56.8%; palmitic acid, 22.4%), fish (DHA, 10.8%; eicosapentaenoic acid, EPA, 16.2%), and soybean oils (oleic, 21.7%; linoleic acid, 54.6%) were compared by coupling the in vitro multi-step and in vivo apparent digestion models using mice. The in vitro digestion rate estimated based on the released free fatty acids content was remarkably higher in soybean and fish oils than in microalgal oil in 30 min; however, microalgal and fish oils had similar digestion rates at longer digestion. The in vivo digestibility of microalgal oil (91.49%) was lower than those of soybean (96.50%) and fish oils (96.99%). Among the constituent fatty acids of the diet oils, docosapentaenoic acid (DPA) exhibited the highest digestibility, followed by EPA, DHA, palmitoleic, oleic, palmitic, and stearic acid, demonstrating increased digestibility with reduced chain length and increased unsaturation degree of fatty acid. The diet oils affected the deposition of fatty acids in mouse tissues, and DHA concentrations were high in epididymal fat, liver, and brain of mice fed microalgal oil. In the present study, microalgal oil showed lower in vitro and in vivo digestibility, despite adequate DHA incorporation into major mouse organs, such as the brain and liver.

Heavy metal sorption using thiolated oils of Elaeis guineensis and Glycine max

Sulphur-modification of matter confers improved heavy metal affinity and could be exploited in the treatment of heavy metal contaminated water. This paper is aimed at comparing the liquid-liquid Ag+ sorption capacities of normal and thiolated: palm oil (PO), palm kernel oil (PKO) and soybean oil (SBO), respectively. The vegetable oils were modified with 1-heptanethiol, and the thioether-functionalized (TF) oils were utilized for the removal of Ag+ present as a contaminant in water, while the unmodified oils acted as controls. The liquid-liquid equilibrium contact time was determined to be 6 hours. The result achieved after equilibration revealed the effectiveness of TF oils in the removal of Ag+ from a 600 ppm AgNO3 simulated water. While TF-SBO reduced the cation concentration to a level less than the detection limit, TF-PKO only showed appreciable sorption capacity (below 30%) relative to the normal oils. The order of Ag+ sorption capacity (TF-SBO &gt; TF-PO &gt; TF-PKO) was ascribed to various levels of unsaturation of fatty acid chains encountered in the lipids. A higher number of sorption-active TF sites is achievable with a greater degree of fatty acid unsaturation. On that note, highly unsaturated vegetable oils (such as that of Glycine max) were recommended.

High efficiency enzymatic synthesis of triglycerides with varying chain length and degree of unsaturation in a solvent‐free system under vacuum

AbstractBACKGROUNDTriglycerides with varying chain length and unsaturation degree are now in high demand in the food and pharmaceutical industries. Enzymatic catalyzed synthesis methods are favored over chemical‐based processes in the commercial production of triglycerides. This study found that the application of vacuum can improve the efficiency and productivity of enzymatic synthesis of various triglycerides using Novozym 435 (EC 3.1.1.3), an immobilized lipase B from Candida antarctica. The system was used for esterification of fatty acids varying in chain length, unsaturation degree, and oxidation degree.RESULTSThe vacuum condition was not applicable to short chain fatty acids (C4–C6) due to loss of fatty acids in the reaction. The conversions of C4–C6 saturated fatty acids were low (15–35%) under atmospheric pressure. Under vacuum, high conversions (&gt;95%) and triglyceride yields (approximately 90%) were achieved in the esterification of glycerol with several medium‐chain and long‐chain (C8–C18) saturated fatty acids. Moreover, unsaturation degree of fatty acids also affected the triglyceride yield. The triglyceride contents synthesized from C18:2n‐6 (76.17 ± 0.45%) was significantly lower (P &lt; 0.05) than those from C18:0 (91.59 ± 1.58%) and C18:1n‐9 (90.77 ± 0.85%). Furthermore, fatty acids with a high oxidation degree had negative effect on triglyceride synthesis. This vacuum solvent free system allowed the synthesis enzyme to be reused 11 times without significant decrease in the lipase activity for esterification of fatty acids.CONCLUSIONThe studied vacuum facilitated triglyceride synthesis process provides an economically attractive yet sustainable solution for the production of a wide range of triglyceride products. © 2020 Society of Chemical Industry

Soluble Sugar and Lipid Readjustments in the Yarrowia lipolytica Yeast at Various Temperatures and pH.

Microorganisms cope with a wide range of environmental challenges using different mechanisms. Their ability to prosper at extreme ambient pH and high temperatures has been well reported, but the adaptation mechanism often remains unrevealed. In this study, we addressed the dynamics of lipid and sugar profiles upon different cultivation conditions. The results showed that the cells grown at various pH and optimal temperature contained mannitol as the major cytosol sugar alcohol. The elevated temperature of 38 °C led to a two- to three-fold increase in total cytosol sugars with concurrent substitution of mannitol for trehalose. Lipid composition in the cells at optimal temperature changed insignificantly at any pH tested. The increase in the temperature caused some drop in the storage and membrane lipid levels, remarkable changes in their composition, and the degree of unsaturated fatty acids. It was shown that the fatty acid composition of some membrane phospholipids varied considerably at changing pH and temperature values. The data showed a pivotal role and flexibility of the sugar and lipid composition of Y. lipolytica W29 in adaptation to unfavorable environmental conditions.

Adaptations of Malus domestica Borkh. (Rosaceae) Fruits Grown at Different Altitudes

Cytophysiological adaptive features of apple fruits (Malus domestica Borkh.) were examined as a function of growth altitude—300, 500, 700, and 1200 m above sea level—in the mountains of the North Caucasus. The altitude-related conditions of apple tree cultivation differed by a range of growth-limiting factors, high irradiance and low temperature in particular. With the use of fruit skins of M. domestica, it was found for the first time that the number of cells containing phenolic substances in the outer cell layers and the amount of accumulated phenols increase with the altitude of tree growth. At higher elevation belts, the content of polyunsaturated fatty acids also increased, which accounted for the rise of the unsaturation index. Phenolic substances protect the fruit peripheral tissues by screening the cells from high doses of UV radiation and by exerting their powerful antioxidant effects. The increased degree of fatty acid unsaturation helps to retain the fluidity of cell membranes in the physiological range at low temperatures. Thus, apple fruits grown at high altitudes adapt to mountain conditions by a suite of structural and functional changes in the peripheral tissues, which facilitates the maintenance of homeostasis in the inner cell layers. The complex rearrangements in fruit tissues of M. domestica trees enable them to grow at high elevation belts under frequently changing conditions and to remain fully productive at various altitudes.

Alteration of Cholesterol Sulfate/Seminolipid Ratio in Semen Lipid Profile of Men With Oligoasthenozoospermia.

The reduction of sperm motility and count, or oligoasthenozoospermia, is one of the major causes of reduced fertility or infertility in men. Lipid composition of spermatozoa is important in determining their functional characteristics, in particular on motility, acrosomal exocytosis or fusogenic properties of the sperm. Here we investigated the levels of semen lipids in 11 infertile patients with severe oligoasthenozoospermia and 9 normozoospermic subjects with normal motility values. Sperm polar and neutral lipids were analyzed by thin-layer chromatography (TLC) and matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-TOF/MS). Semen of patients with oligoasthenozoospermia showed a reduction of the degree of fatty acid unsaturation in the phospholipids chains that might affect the membrane fluidity. Furthermore, a significant higher cholesterol sulfate/seminolipid ratio was found in semen of oligoasthenozoospermic patients than in subjects with normal motility values, suggesting a critical role of sulfolipids in semen quality. The results may facilitate the understanding of the role of lipids on male fertility and offer interesting perspectives to find innovative treatments for oligoasthenozoospermia.

The effect of fatty acid profile on the stability of non-traditional and traditional plant oils

&#x0D; The effect of fatty acid composition on the autoxidation of selected plant oils (rapeseed (canola) oil, corn oil, frying oil, grapeseed oil, pomace olive oil, rice bran oil, sunflower oil and high oleic sunflower oil) during their storage was studied. Oils were purchased in retail food stores. Oxidative stability of plant oils was monitored during the storage under the Schaal test conditions at 60 °C in 100 mL beakers and the dark for 40 days. The weight changes, the peroxide and acid values were analysed during the storage. Changes in the composition of fatty acids were analyzed by the gas chromatography-mass spectrometry. The results obtained by monitoring the weight changes of oils correlated with their peroxide values. The induction period in case of grapeseed and sunflower oils was 27 and 28 days respectively. The induction period for frying and rapeseed oils were around 35 days. The remaining four oils had induction periods over 40 days. The acid values at the end of experiment correspond to both the relative weight gain and the the peroxide values. The stability of oils depended mainly on the degree of fatty acids unsaturation. A strong negative correlation between oleic acid content and oil stability expressed as the peroxide value was found. The significant positive correlation was found in case of linoleic acid. The relative content of polyunsaturated fatty acids decreased during the storage while the content of saturated and monounsaturated fatty acids increased. The highest relative increase in oleic acid was found at the least stable oils, grapeseed and sunflower oils, by 37.5% and 25.3% respectively. The initial content of free fatty acids monitored by the acid value did not affect the oxidation rate. With consideration to all monitored parameters the grapeseed and the sunflower oils were the least stable. The most stable ones were olive pomace and high oleic sunflower oils.&#x0D; &#x0D;

Associations of Aerobic Fitness and Maximal Muscular Strength With Metabolites in Young Men

High physical fitness is associated with a reduction in risk of cardiovascular diseases and death, but the underlying mechanisms are insufficiently understood. To determine how aerobic fitness and muscular strength are associated with serum metabolome measures. This cross-sectional study included Finnish men receiving military refresher training from May 5, 2015, to November 28, 2015, representing partly overlapping groups of individuals with the lowest vs highest aerobic fitness and the lowest vs highest muscular strength. Data analyses were conducted from January 1, 2018, to May 31, 2019. The associations of aerobic fitness (determined with maximum oxygen consumption in milliliters per minute per kilogram, measured with maximal cycle ergometer test) and muscular strength (determined with a maximal strength test for lower extremities in kilograms) with 66 metabolome measures from fasting serum samples (nuclear magnetic resonance-based metabolomics) were analyzed. Participants included 580 Finnish men (mean [SD] age, 26.1 [6.5] years). Including overlap between groups, there were 196 men in the lowest aerobic fitness group and 197 men in the highest aerobic fitness group as well as 196 men in the lowest muscular strength group and 197 men in the highest muscular strength group. Of 66 studied metabolome measures, 48 differed between high vs low aerobic fitness groups, including small very low-density lipoprotein (standardized median difference, -0.67; 95% CI, -0.83 to -0.49), large high-density lipoprotein (standardized median difference, 0.89; 95% CI, 0.69-1.15), total triglyceride levels (standardized median difference, -0.52; 95% CI, -0.65 to -0.34), isoleucine (standardized median difference, -0.37; 95% CI, -0.55 to -0.16), leucine (standardized median difference, -0.55; 95% CI, -0.72 to -0.34), phenylalanine (standardized median difference, -0.54; 95% CI, -0.71 to -0.32), glycerol (standardized median difference, -0.64; 95% CI, -0.81 to -0.48), and glycoprotein (standardized median difference, -0.78; 95% CI, -0.95 to -0.62) concentration, a high unsaturation degree of fatty acids (standardized median difference, 0.59; 95% CI, 0.42-0.81), and apolipoprotein B to apolipoprotein A1 ratio (standardized median difference, -0.88; 95% CI, -1.08 to -0.67). Adding aerobic fitness into the regression model after age, education, smoking, use of alcohol, and dietary factors accounted for more than an additional 5% of variation for 25 metabolome measures (R2 range, 5.01%-15.90% by measure). With these 2 criteria, maximal muscular strength was not associated with any metabolome measures. Aerobic fitness was associated with high large high-density lipoprotein particle concentration (R2, 14.97%; 95% CI, 10.65%-20.85%), low apolipoprotein B to apolipoprotein A1 ratio (R2, 14.49%; 95% CI, 10.58%-19.51%), and low glycoprotein concentration (R2, 15.90%; 95% CI, 11.22%-21.51%). Aerobic fitness was also associated with low very low-density lipoprotein, triglyceride, isoleucine, leucine, phenylalanine, glycerol, and glycoprotein concentrations and with a high unsaturation degree of fatty acids. Adjusting for recent physical activity influenced the results minimally. Adjusting for body fat percentage showed that some of the associations were mechanistically associated with body fat percentage. This study provides data on the association of high aerobic fitness with underlying oxidative lipid metabolism associated with a reduction in cardiometabolic risk. High maximal muscular strength is not similarly associated with these benefits.

Lipids and soluble carbohydrates in the mycelium and ascomata of alkaliphilic fungus Sodiomyces alkalinus.

Alkaliphilic fungi are fundamentally different from alkalitolerant ones in terms of mechanisms of adaptation. They accumulate trehalose in cytosoland phosphatidic acids (PA) in the membrane lipids, whereas alkalitolerants contain these compounds in low amounts. But it is unclear how the composition of osmolytes and lipids changes during cytodifferentiation. In this article the composition of lipids and soluble cytosol carbohydrates in the mycelium and fruit bodies of the alkaliphilic fungus Sodiomyces alkalinus was studied. In the mycelium, mannitol and trehalose dominated, while in fruit bodies only trehalose was predominant. Phosphatidylcholines (PC), PA and sterols were major membrane lipids of the mycelium, while PC and sterols were predominant in fruit bodies. The degree of fatty acids unsaturation of the main mycelium phospholipids (PC and PA) increased with age, while that of PC did not change regardless of the developmental stage. In young mycelium, storage lipids were represented mainly by free fatty acids, and in mature mycelium and fruit bodies-by triacylglycerols. Fruit bodies contained three times less membrane lipids and twice as many storage lipids as mycelium. Trehalose was the main cytosol carbohydrate in the mycelium and fruit bodies, which confirms its key value for alkaliphily.

PH and lipid unsaturation impact the formation of acrylamide and 5-hydroxymethylfurfural in model system at frying temperature.

The effect of unsaturated free fatty acids (FFAs) and triglycerides (TGs) on the formation of acrylamide and 5-hydroxymethylfurfural (HMF) at frying temperature was investigated. We hypothesized that the nature of the precursors generated by the Maillard reaction in the presence of FFAs and TGs, such as the Amadori product and α-dicarbonyl compounds, would impact acrylamide and HMF formation. Interestingly, the initial pH of the aqueous phase impairs the observed effect of the addition of lipids on the formation of acrylamide. Addition of FFAs and TGs increased acrylamide formation in non-buffered systems (distilled water, pH 4.6), but decreased it in buffered systems (sodium acetate, pH 6.0). Conversely, incorporation of these lipids promoted HMF formation under both conditions. The degree of fatty acid unsaturation played an important role in the formation of acrylamide and HMF. The effect of unsaturated lipids on the acrylamide and HMF was due to lipid oxidation. Statistical correlations were made between acrylamide and HMF formation and α-dicarbonyl compounds in the presence of unsaturated lipids.

Fatty acid metabolic flux and lipid peroxidation homeostasis maintain the biomembrane stability to improve citrus fruit storage performance

Little is known about the variations of fresh fruit biomembrane and its physiological and biochemical characteristics during storage. A navel orange mutant ‘Gannan No.1’ (Citrus sinensis Osbeck) showed higher membrane stability and titratable acid while lower calyx senescence compared with wild-type ‘Newhall’. The membrane damage was significantly reduced in ‘Gannan No.1’ under 10% polyethylene-glycol (41.16% vs. 8.77%) and 30% polyethylene-glycol (52.59% vs.16.11%) treatments on day 45 after harvest. Consistently, membrane electrolyte leakage and malondialdehyde were significantly decreased in ‘Gannan No.1’, and superoxide dismutase and glutathione reductase were activated. A metabolic analysis was performed to evaluate membrane fatty acid unsaturation and peroxidation. Linolenic acid and hexadecylenic acid contributed to the higher degree of unsaturated fatty acids in ‘Gannan No.1’. Furthermore, ‘Gannan No.1’ accumulated stress-resistant metabolites such as proline, α-tocopherol and glutathione. Correlation analysis of membrane homeostasis indexes with quality parameters showed the importance of biomembrane stability in maintaining citrus fruit quality.

Understanding the stress responses of Kluyveromyces marxianus after an arrest during high-temperature ethanol fermentation based on integration of RNA-Seq and metabolite data.

The thermotolerant Kluyveromyces marxianus is a potential candidate for high-temperature ethanol fermentation. Although K. marxianus exhibited high ethanol productivity at 45°C during the early fermentation stage, we observed a fermentation arrest due to the accumulated inhibitors. The stress responses of K. marxianus during high-temperature fermentation were revealed based on integration of RNA sequencing (RNA-Seq) and metabolite data. High temperature stimulated mitochondrial respiration but repressed the tricarboxylic acid (TCA) cycle, leading to increased generation of reactive oxygen species (ROS) and a lowered ratio of reduced nicotinamide adenine dinucleotide (NADH)/oxidized nicotinamide adenine dinucleotide (NAD+). Glycerol production was enhanced during the early fermentation stage, which might contribute to NADH reoxidation and ROS generation. Excess ROS could be neutralized by reduced nicotinamide adenine dinucleotide phosphate (NADPH) that might be reserved in the following ways: (1) decreased biosynthesis of branched-chain amino acids (BCAAs) reduced NADPH consumption; (2) enhanced acetic acid production increased NADPH regeneration. The degree of fatty acid unsaturation was also reduced to adapt to high temperature. In addition, stress responses were also observed after the fermentation arrest at 45°C. Genes related to peroxidase activity, iron-sulfur cluster assembly, and flavin mononucleotide (FMN) binding were downregulated, while genes associated with DNA repair and lipid composition of the plasma were upregulated. The yeast also produced more ergosterol to deal with ethanol stress. This study gains comprehensive insights into the K. marxianus transcriptome under various stresses during high-temperature ethanol fermentation, providing rich information for further metabolic engineering towards improved stress tolerance and ethanol production.

Antioxidant Metabolism, Photosystem II, and Fatty Acid Composition of Two Tall Fescue Genotypes With Different Heat Tolerance Under High Temperature Stress.

Tall fescue (Festuca arundinacea Schreb.) is a typical and widely used cool-season turf grass. High temperature is a key factor that limits its utility. The objectives of this study were to investigate the behaviors of fatty acid composition and its gene expression patterns in heat-resistant genotype “TF71” and heat-sensitive genotype “TF133” exposed to heat stress (40/35°C, 14/10 h), and to broaden our comprehension about the relationship between heat tolerance and fatty acid function. The result showed that heat stress increased the malondialdehyde (MDA) content and relative electrolyte leakage (EL), but decreased the level of chlorophyll and the activity of superoxide dismutase (SOD) and peroxidase (POD) when compared to the controls, to a greater extent in “TF133.” This result proved that “TF71” had superior high-temperature resistance. Furthermore, comparing the changes in the composition of fatty acid and the expression of the genes involved in its synthesis between the two different genotypes under heat stress, we found that heat stress increased the degree of unsaturation, UFA/SFA, and double bond index (DBI) in “TF71.” Moreover, quantitative RT-PCR revealed that heat stress altered the expression of the genes involved in fatty acid synthesis, including ACAC, FabD, FabF, FabH, FabI, and FatA. According to these findings, we can speculate that increasing the unsaturation degree of fatty acid or controlling the equilibrium ratio of UFA/SFA might be closely associated with the improving of the heat resistance in tall fescue.

Biomass and lipid production of a novel microalga, Chlorellaceae sp. P5, through heterotrophic and swine wastewater cultivation

A potential novel genus of microalgae was isolated from swine wastewater. According to a phylogenetic analysis of 18S rRNA and internal transcribed spacer (ITS) sequences, as well as the ITS2 secondary structure, this strain was designated as Chlorellaceae sp. P5. Acclimatization to various temperatures, pH conditions, and salinities demonstrated that this strain can grow at temperatures of 20 °C–40 °C, in an acidity range of pH 4–7, and with salinity as high as 3% NaCl. To optimize biomass production, response surface methodology was used which included variables associated with carbon and nitrogen sources. In this study, flask cultivation yielded 1.66 g l−1 d−1 of biomass under 15.19 g l−1 glucose and 8.26 mM ammonium bicarbonate. The fatty acid composition suggested that the lipid from Chlorellaceae sp. P5 can be typically used for biodiesel production, with a low degree of unsaturated fatty acids. Moreover, a high content of the first-limiting amino acid (lysine) and 9,12-Octadecadienoic acid (linoleic acid, C18:2) for nutritional supplements was also observed. With respect to swine wastewater treatment, the isolated strain showed an excellent removal rate of ammonia and phosphate over 97.3 mg l−1 of NH3-N and 20.3 mg of l−1 PO43− in the sterilized and none-sterilized wastewater. The biomass and lipid derived from Chlorellaceae sp. P5 can be attained at 0.49 g l−1 d−1 and 0.13 g l−1 d−1 by swine wastewater cultivation with 5% CO2 supply, respectively. According to the various characteristic analyses, Chlorellaceae sp. P5 has great potential for different industrial developments such as biodiesel and wastewater treatment.

Ultrasound-assisted chemoenzymatic epoxidation of soybean oil by using lipase as biocatalyst

The present work reports the use of ultrasonic irradiation for enhancing lipase catalyzed epoxidation of soybean oil. Higher degree of unsaturated fatty acids, present in the soybean oil was converted to epoxidized soybean oil by using an immobilized lipase, Candida antarctica (Novozym 435). The effects of various parameters on the relative percentage conversion of the double bond to oxirane oxygen were investigated and the optimum conditions were established. The parameters studied were temperature, hydrogen peroxide to ethylenic unsaturation mole ratio, stirring speed, solvent ratio, catalyst loading, ultrasound frequency, ultrasound input power and duty cycle. The main objective of this work was to intensify chemoenzymatic epoxidation of the soybean oil by using ultrasound, to reduce the time required for epoxidation. Epoxidation of the soybean oil was achieved under mild reaction conditions by indirect ultrasonic irradiations (using ultrasonic bath). The relative percentage conversion to oxirane oxygen of 91.22% was achieved within 5h. The lipase was remarkably stable under optimized reaction conditions, later was recovered and reused six times to produce epoxidized soybean oil (ESO).