Total Fatty Acid Composition Research Articles

Deletion of MHY1 abolishes hyphae formation in Yarrowia lipolytica without negative effects on stress tolerance.

There is a need for development of sustainable production processes for production of fats/oils and lipid derived chemicals. The dimorphic oleaginous yeast Yarrowia lipolytica is a promising organism for conversion of biomass hydrolysate to lipids, but in many such processes hyphae formation will be problematic. We have therefore constructed and compared the performance of strains carrying deletions in several published gene targets suggested to abolish hyphae formation (MHY1, HOY1 and CLA4). The MHY1-deletion was the only of the tested strains which did not exhibit hyphae formation under any of the conditions tested. The MHY1-deletion also had a weak positive effect on lipid accumulation without affecting the total fatty acid composition, irrespective of the nitrogen source used. MHY1 has been suggested to constitute a functional homolog of the stress responsive transcription factors MSN2/4 in Saccharomyces cerevisiae, the deletion of which are highly stress sensitive. However, the deletion of MHY1 displayed only minor difference on survival of a range of acute or long term stress and starvation conditions. We conclude that the deletion of MHY1 in Y.lipolytica is a reliable way of abolishing hyphae formation with few detectable negative side effects regarding growth, stress tolerance and lipid accumulation and composition.

Composition analysis of fatty acids and stereo-distribution of triglycerides in human milk from three regions of China

Understanding the components composition characteristics of human milk is conductive for the development of infant formulas. The total fatty acids composition and the stereo-distribution of fatty acids in human milk triglycerides (TGs) from three regions (Zhengzhou, Wuhan and Harbin) of China were analyzed. The total and intrapositional fatty acids composition of human milk TGs showed significant differences among three regions. Zhengzhou, Harbin and Wuhan human milk possessed highest levels of medium-chain fatty acids (MCFA, 6.36 ± 1.46%), short-chain fatty acids (SCFA, 0.10 ± 0.03%) and monounsaturated fatty acids (MUFA, 34.61 ± 0.45%), and polyunsaturated fatty acids (PUFA, 30.34 ± 0.33%), respectively. The preference distribution of fatty acids in human milk TGs was hardly affected by regions, for the relative conservative interpositional levels of each fatty acids in three regions. Not only the specific distribution of sn-2 position, but the esterification of fatty acids in sn-1 and sn-3 positions also had preference. SCFA and MCFA were mainly esterified at sn-3 position, but LCSFA most unlikely distributed at the sn-3 position. The preference esterification of MUFA were sn-1, sn-3 > sn-2, and PUFA were sn-3 > sn-1 > sn-2. Therefore, the optimization of infant formulas not only needs considering total fatty acid composition of TGs but requires thinking over the stereo-distribution of fatty acids.

Impact of sunflower (Helianthus annuus L.) plastidial lipoyl synthases genes expression in glycerolipids composition of transgenic Arabidopsis plants

Lipoyl synthases are key enzymes in lipoic acid biosynthesis, a co-factor of several enzyme complexes involved in central metabolism. Plant pyruvate dehydrogenase complex (PDH), located in mitochondria and plastids, catalyses the first step of fatty acid biosynthesis in these organelles. Among their different components, the E2 subunit requires the lipoic acid prosthetic group to be active. De novo lipoic acid biosynthesis is achieved by the successive action of two enzymes on octanoyl-ACP: octanoyltransferase (LIP2) and lipoyl synthase (LIP1). In this study, two plastidial lipoyl synthase genes from sunflower (Helianthus annuus L.) were identified (HaLIP1p1 and HaLIP1p2), sequenced and cloned in a heterologous production system (Escherichia coli). Gene expression studies revealed similar expression patterns for both isoforms, with a slight predominance of HaLIP1p1 in vegetative tissues and mature seeds. Tertiary structural models for these enzymes indicate they both have the same theoretical catalytic sites, using lipoyl-lys and 5-deoxyadenosine as docking substrates. The fatty acid profile of E. coli cells overexpressing HaLIP1p1 and HaLIP1p2 did not present major differences, and the in vivo activity of both proteins was confirmed by complementation of an E. coli JW0623 mutant in which lipoyl synthase is defective. Although no significant differences were detected in the total fatty acid composition of transgenic Arabidopsis thaliana seeds overexpressing any of both proteins, a lipidomic analysis revealed a redistribution of the glycerolipid species, accompanied with increased phosphatidylethanolamine (PE) content and a decrease in diacyglycerols (DAG) and phosphatidylcholine (PC). Depletion of the SAM co-factor caused by HaLIP1p1 and HaLIP1p2 overexpression in transgenic plants could explain this remodelling through its effects on PC synthesis.

Proximate and Total Fatty Acid Composition of Some Aquatic Macrophytes in the Nile River Rayahs, Egypt

Proximate and Total Fatty Acid Composition of Some Aquatic Macrophytes in the Nile River Rayahs, Egypt

A Fast and Green Extraction Method for Berry Seed Lipid Extraction Using CO2 Expanded Ethanol Combined with Sonication

AbstractIn this work, a combination of sonication and carbon dioxide expanded liquid extraction (SA‐CXLE) is used for the first time for the extraction of lipids from berry seeds. Three solvents (ethanol, methanol and ethyl lactate) are screened for the best recoveries of total lipids. Ethanol is selected due to its efficiency, greenness and sustainability. The effects of operation variables including temperature, time and CO2 molar fraction on extraction performance are examined using a response surface methodology. The optimum conditions were found at 0.37 molar fraction of CO2 in ethanol, a temperature of 52 °C and an extraction time of 7 min for two cycles. The SA‐CXLE method extracts 323 ± 38 mg g−1 seed compared to 194 ± 23 using a conventional solid‐liquid extraction. SA‐CXLE is successfully applied to profile lipids from gooseberry, blackcurrant, chokeberry, red currant, and rowanberry seeds. More than 17 lipid classes are characterized and identified. Gooseberry shows the highest amount of oil of 352 mg g−1 seed.Practical Applications: The developed method provides a fast, efficient and simple approach to extract and profile lipids using a combination of green solvents. Total lipid content and fatty acids composition of the berry seeds are essential information in pharmaceutical, cosmetic, food and nutritional applications.

Fatty Acid Composition of Hepatopancreas and Gonads in Both Sexes of Orange Mud Crab, Scylla olivacea Cultured at Various Water Flow Velocities.

Nutritional quality of the hepatopancreas and gonads of orange portunid mud crab, Scylla olivacea was evaluated for each gender under four treatment of different water velocities (0, 20, 40 and 60 cm s−1), in terms of nutrient reserve and nutrient for reproduction. About 56 crabs were used in this study in which fatty acids composition was analysed using gas chromatography mass-spectrometry (GC-MS). For hepatopancreas analysis, monounsaturated fatty acids (MUFAs) were present in the highest fatty acids concentration, followed by polyunsaturated fatty acids (PUFAs) and, saturated fatty acids (SFAs). However, long-chain polyunsaturated fatty acids (LC-PUFAs) were displayed in low concentration in the hepatopancreas. Total fatty acid (TFAs) composition was significantly higher at moderate velocity of 20 cm s−1 compared to other water velocity treatments. For gonad analysis, 20 cm s−1 showed the highest TFA concentration of 93.34 mg g−1 while, the lowest concentration of 3.90 mg g−1 occurred at 0 cm s−1. There were significant differences in male and female crab’s fatty acids contents of gonads at all flow velocities challenged (p < 0.05). PUFAs and MUFAs were dominant while, SFAs were observed at low concentration. This study revealed that, concentration of PUFAs increased as gonad maturation increased. The decreasing concentration of hepatopancreas fatty acids over the culture period indicated that nutrient was shifted from the hepatopancreas, to be used as energy reserved to gonads for further growth of eggs and offspring. The linkages between water flow strength, hepatopancreas, and gonad fatty acids concentrations, is fundamental knowledge useful in establishing efficient habitat velocities selection which will improve aquaculture production of mud crabs with high quality broodstock.

Total Lipids Content, Lipid Class and Fatty Acid Composition of Ten Species of Microalgae.

Microalgae is a potential producer of functional lipids such as n-3 polyunsaturated fatty acids (PUFA) and fucoxanthin. In the present study, lipids from ten microalgae species were analyzed especially focusing on the fucoxanthin, lipid and fatty acid compositions. The study revealed a remarkable variation in total lipids content, fucoxanthin content, lipid class composition and n-3 PUFA content in individual species, although they belong to the same genus. Among microalgae examined, Pavlova lutheri contained the highest total lipids content (313.59 mg g-1 dry weight) and considerable amount of fucoxanthin (3.13 mg g-1 dry weight). It also had the highest level (28.01%) of total n-3 PUFA with high level of eicosapentaenoic acid (EPA) (17.76%) and docosahexaenoic acid (DHA) (7.61%). The highest fucoxanthin content (5.19 mg g-1 dry weight) was observed in Chaetoceros gracilis. C. gracilis also contained relatively high level of total lipids (228.87 mg g-1 dry weight) and 10.67% EPA. The results also demonstrated that Nannochloropsis oculata contained the greatest amount of EPA (26.21%), while Isochrysis galbana had the highest level of DHA (8.76%). And both microalgae contained 1.71 and 4.44 mg g-1 dry weight fucoxanthin, respectively. Microalgal lipids containing abundant fucoxanthin and n-3 PUFA such as EPA and DHA in the present study will be used as nutraceutical lipids with great commercial potential.

Retention of Carotenes and Vitamin E, and Physico-chemical Changes Occurring upon Heating Red Palm Olein Using Deep-fat Fryer, Microwave Oven and Conventional Oven.

Red palm olein is known to be high in carotenes and vitamin E (tocols) and possess various nutritional benefits. This study evaluates the effect of prolonged heating using three common cooking techniques i.e. deep-fat fryer, microwave oven and conventional oven, on the profiles of carotenes and tocols as well as the physico-chemical changes occurring in red palm olein when compared to conventional palm olein. Physico-chemical changes in all oils were gauged based on their peroxide, p-anisidine and total oxidation values, acidity, and fatty acid composition. Both red palm olein and palm olein were thermally stable based on their lower rate of hydrolytic and oxidative degradations as well as higher tocols retention, which allow the oils to undergo heating up to 3 hours using deep-fat fryer and conventional oven. Nevertheless, red palm olein seemed not suitable for prolonged heating processes considering lower retention of carotenes. Microwave heating also influenced the stability of phytonutrients.

Vegetable ingredient in cheese product

Sesame seeds are a functional food ingredient with vasoprotective, antioxidant, prebiotic, chondro- and osteoprotective characteristics. In this study, sesame seeds were used to enrich a cheese product. The dose, method and technological production stage of the cheese product in which to add sesame seeds were determined, in addition to the effect of sesame seeds on the product’s quantitative indicators. The nutritional value of sesame seeds, their total amino acid and fatty acid compositions and microbiological parameters were evaluated, depending on the method of the filler temperature treatment. The appropriate heat treatment method was holding the functional component in milk at 73 ±2 °C for 25 min, followed by cooling to 30 ±2 °C. Adding the filler into the cheese mass before moulding the cheese head was determined as the appropriate technological step to introduce the previously prepared sesame seeds. The cheese product was found to have the best sensory characteristics at the 3% sesame seed dose compared with the doses of 1% and 5%. The cheese product enriched with sesame seeds can be recommended as a functional product for systematic consumption without restrictions for all groups in a healthy population.

Chemical-Sensory Traits of Fresh Cheese Made by Enzymatic Coagulation of Donkey Milk.

Making cheese from donkey milk is considered unfeasible, due to difficulties in coagulation and curd forming. Two recent studies have reported the protocols for making fresh cheese by using camel chymosin or calf rennet, but the chemical and sensory characteristics of the products were not thoroughly investigated. The present paper aims to give a further contribution to the field, by investigating cheesemaking with microbial rennet and evaluating the chemical composition, total fatty acid, volatile organic compounds (VOCs) and sensory profile of the resultant product. Six trials were undertaken at laboratory scale on donkey milk from a Martina Franca ass, by applying the technological scheme as reported for calf rennet, with some modifications. Bulk cow milk was used as a control. Donkey milk coagulated rapidly, but the curd remained soft, and was only suitable for making fresh cheese; differently, cow milk coagulated almost instantaneously under these strong technological conditions, giving rise to a semi-hard curd in very short time. The moisture level of donkey cheese was almost the same as reported in the literature, whereas the yield was higher, probably due to the high protein content of the milk used. The total fatty acid composition of cheese presented some differences with respect to milk, mostly consisting in a higher presence of saturated compounds. A connection with a better retention of the large sized fat globules into the curd was hypothesised and discussed. The VOC analyses, performed by solid-phase micro extraction gas chromatography-mass spectrometry, allowed the identification of 11 compounds in milk and 18 in cheese. The sensory characteristics of donkey cheese were strongly different with respect to the control, and revealed unique and pleasant flavours.

Effect of experimental thermal stress on lipidomes of the soft coral Sinularia sp. and its symbiotic dinoflagellates

A complete or partial loss of symbiotic dinoflagellates (SD) by the corals in response to thermal stress has been described as coral bleaching. A stress damages the photosynthetic apparatus of SD and their thylakoid membranes, and symbiotic alga cells disappear via exocytosis and/or apoptosis resulting in a disturbance of host cell membranes. Lipids play an essential role in coral metabolism and constitute the basis of membranes. At present, studies of coral bleaching typically deal with long-term lipid indices, such as total lipids and fatty acids (FAs), while short-term dynamics of lipidome (full range of all lipid molecular species) has not been considered in the context of bleaching mechanism. To evaluate the lipidomic approach to characterizing coral bleaching, the soft coral Sinularia sp. was exposed to a short-term experimental thermal stress (33 °C). The dynamics of chlorophyll level, the composition of total FAs, the amounts of total lipids and major lipid classes (such as wax esters (WE), triacylglycerols (TAG), and monoalkyldiacylglycerols (MADAG), glycolipids, ethanolamine-, choline-, serine-, inositolglycerophospholipids (PE, PC, PS, PI), and ceramide aminoethylphosphonate (CAEP)) and the variations in the content of lipid molecular species were studied during a 36-h heat exposure. >160 molecular species were identified by tandem high-resolution mass spectrometry. Under the short-term stress, a considerable decline in the levels of chlorophylls, glycolipids, and FA markers of SD was detected, whereas the variations in the content of total lipids, total phospholipids, and major FAs were not significant. The heat exposure immediately disturbed the daily cycle of the composition of glycolipid molecular species. Among the storage lipids, the content of TAG and MADAG decreased, whereas the content of polyunsaturated WE molecular species increased under the stress. The following effects were recorded for the structural lipids: a depletion in the PE, PC, and PI amounts, a conversion of PE into their lyso and oxidized derivatives, an appearance of diacyl form of PE, and a disturbance of transfer of some polyunsaturated FAs from SD to the host. The content of PS was relatively stable. Probably, PE molecular species are a primary target of thermal stress in the Sinularia host. The most dramatical changes in the Sinularia lipidome were detected between 24 h and 36 h of the exposure. A lipidomic approach is important for studies of dynamics of the coral symbiotic association and a resistance of different coral taxa during short-term bleaching events.

Effect of Maturity and Environmental Conditions on Chemical Composition of Olive Oils of Introduced Cultivars in Morocco

This work aims at evidencing the quality and chemical composition of extra virgin olive oils according to stages of maturity and in relation to the geographical location of olives. Three different olive cultivars (Moroccan Picholine, Languedoc Picholine, and Frantoio), grown in two different locations in Morocco (Errachidia and Marrakech), were studied during the two crop years (2016 and 2017) at three stages of maturity (green, purple, and black). This work has been carried out by analyzing several parameters, such as the quality characteristics (acidity and peroxide value), the chemical composition (total phenol content and fatty acid composition) of the oils, and also the fruit characteristics of the olives (maturity index, fruit water content, and oil content). The results obtained in this study indicate that as maturity advanced, there was a slight rise in oil content and acidity, while there was a decrease in fruit water content and peroxide value in both locations during the two crop years. The fatty acid composition of extra virgin olive oil showed a significant increase of linoleic acid and polyunsaturated fatty acids (PUFAs) and a decrease of oleic acid, palmitic acid, monounsaturated fatty acids (MUFAs), and MUFA/PUFA ratio as the maturation process progressed. A significant gradual decrease was noted in total phenol content and bitterness intensity from the green stage to the black. Moreover, olive oil composition differed clearly between the two sites. Therefore, the olive cultivar, harvesting date, and geographic location influence the olive oil characteristics.

Growth rate and fatty acid composition of orange mud crab instars, Scylla olivacea, reared at different temperatures

The objective of the present study was to examine the effect of different rearing temperatures on growth, survival, instar development, and fatty acid (FA) composition of orange mud crab instars, Scylla olivacea. The experiment was conducted at four different water temperatures of 24 °C, 28 °C, 32 °C and 36 °C using instar stage 1 (C1) in temperature-controlled recirculating rearing systems and lasted for 30 days. The study findings revealed that higher temperatures (≥32 °C) significantly reduced intermolt duration, whereby most crabs reached instar stages C6-C7, although 10.3% were still in the C2−C3 developmental stage. In addition, at temperature 36 °C all crabs were dead after three days of culture. Surprisingly, at constant temperature of 28 °C, total Polyunsaturated Fatty Acid were lower (0.52) compared to those at lower, 24 °C (0.71) and higher temperature of 32 °C (0.74). However, the direct effects of temperature on total fatty acids composition in crabs could not be distinguished from indirect effects of variable crab size and molt number. In conclusion, high temperature of 32 °C negatively affects instars growth and may induce molting, especially in S. olivacea.

Lipidomic study of the influence of dietary fatty acids on structural lipids of cold-water nudibranch molluscs

Nudibranch molluscs occur in marine ecosystems worldwide and prey on numerous invertebrate species. During feeding, dietary fatty acids (FAs) unusual for nudibranchs are transferred to their lipids. Normal biomembrane functions require stable composition of structural polar lipids (PL), but the pathways of dietary FA utilization to PL in nudibranchs still remain unknown. A combination of chromatography and tandem high-resolution mass spectrometry was used to determine total lipid, PL, FA, and PL molecular species composition of two cold-water species of Dendronotus, which then were compared with those of Tritonia tetraquetra. The use of FA trophic markers showed that Dendronotus sp. and T. tetraquetra prey on different soft corals, while D. robustus may consumes hydrocorals and bryozoans. Nudibranch FA profiles were strongly modified by dietary FAs but their PL profilers were similar. Dietary FAs are not included in ceramide aminoethylphosphonate and inositol glycerophospholipids, but directed to ethanolamine, choline, and serine glycerophospholipids and, in some cases, form isobaric molecular species with different FA chain lengths. For such isobaric species, nudibranchs reduce the length of alkyl groups when very-long-chain FAs are obtained with diet. This molecular mechanism may explain the adaptation of nudibranch membrane structure to dietary input of unusual FAs.

Total Lipid Content and Fatty Acid Composition of Seeds of Some Wild Achillea Species

Total Lipid Content and Fatty Acid Composition of Seeds of Some Wild Achillea Species

Oxidation and Polymerization of Triacylglycerols: In-Depth Investigations towards the Impact of Heating Profiles.

The stability of refined, bleached, and deodorized palm olein (RBDPO) was studied under controlled heating conditions. RBDPO was heated continuously for 24 h at 160, 170, and 180 °C, with oil sampled at four hour intervals. Thermo-oxidative alterations were measured through various parameters, such as monomeric oxidized triacylglycerols (oxTAG), total polar compounds (TPC), polymerized triacylglycerols (PTG), oxidative stability, and fatty acid composition. After 24 h of heating, the TPC and triacylglycerol oligomers showed a linear increase with heating time at all heating temperatures. At the end of the heating study, more epoxy acids were formed than keto and hydroxy acids. Moreover, caprylic acid, which was not present in fresh oil, was formed in significant amounts. The increase in oxTAG was strongly correlated with the increase in the p-anisidine value and total oxidation value. The decreases in diacylglycerol and free fatty acids were strongly correlated with an increase in PTG.

DEHP and DINP Induce Tissue- and Gender-Specific Disturbances in Fatty Acid and Lipidomic Profiles in Neonatal Mice: A Comparative Study.

Di-isononyl phthalate (DINP) is considered one of the main industrial alternatives to di(2-ethylhexyl)phthalate (DEHP), a well-known chemical with various toxic effects including the disruption with lipid metabolism. However, the potential effects of DINP on lipid metabolism have rarely been investigated in mammals. Our study demonstrated that exposure of neonatal mice to DEHP and DINP at a daily dose of 0.048 or 4.8 mg/kg from postnatal day 0 (PND0) to PND21 caused nonmonotonic as well as tissue- and gender-specific alterations of total fatty acid (FA) compositions in plasma, heart, and adipose tissues. However, the patterns of disruption differed between DEHP- and DINP-treated groups. On the basis of targeted lipidomic analyses, we further identified gender-specific alterations of eight lipid classes in plasma following DEHP or DINP exposure. At the higher dose, DEHP induced decreases in total phosphatidylcholines and phosphatidylinositol (PI) in females and increases in phosphatidylethanolamines (PEs) and triglycerides in males. By contrast, DINP at the higher dose caused alterations of PEs, PIs, phosphatidylserines, and cholesterols exclusively in male mice, but no changes were observed in female pups. Although the most significant dysregulation of lipid metabolism was often observed for the higher dose, the lower one could also disrupt lipid profiles and sometimes its effects may even be more significant than those induced by the higher dose. Our study for the first time identified tissue- and gender-specific disruptions of FA compositions and lipidomic profiles in mice neonatally exposed to DINP. These findings question the suitability of DINP as a safe DEHP substitute and lay a solid foundation for further elucidation of its effects on lipid metabolism and underlying mechanisms.

Enhancing lipid nutritional quality of oysters by hybridization betweenCrassostrea gigasandC. angulata

In the present study, hybrid and inbred oysters were produced by factorial hybridization between two closely related species, the Pacific oyster Crassostrea gigas and the Portuguese oyster C. angulata. Tissues samples were used for the analysis of total lipid content (TLC) and fatty acid composition (FAC). In general, FAC but not TLC in hybrid oysters was significantly different from inbred oysters. Hybrid oysters have significantly lower ∑SFA composition but higher ∑PUFA composition than inbred oysters, with heterosis for ∑SFA, ∑MUFA and ∑PUFA of −6.03%, −6.53% and 14.31% respectively. Moreover, hybrid oysters have significantly higher EPA + DHA content and n3/n6 PUFA ratio than inbred oysters, indicating higher lipid nutritional quality than inbred oysters. Among them, the hybrid ♀ C. gigas × ♂ C. angulata appears to be the most nutritious. These results indicated that the lipid nutritional quality of oysters can be improved by hybridization.

Evaluating coral trophic strategies using fatty acid composition and indices.

The ecological success of shallow water reef-building corals has been linked to the symbiosis between the coral host and its dinoflagellate symbionts (herein ‘symbionts’). As mixotrophs, symbiotic corals depend on nutrients 1) transferred from their photosynthetic symbionts (autotrophy) and 2) acquired by host feeding on particulate organic resources (heterotrophy). However, coral species differ in the extent to which they depend on heterotrophy for nutrition and these differences are typically poorly defined. Here, a multi-tracer fatty acid approach was used to evaluate the trophic strategies of three species of common reef-building coral (Galaxea fascicularis, Pachyseris speciosa, and Pocillopora verrucosa) whose trophic strategies had previously been identified using carbon stable isotopes. The composition and various indices of fatty acids were compared to examine the relative contribution of symbiont autotrophy and host heterotrophy in coral energy acquisition. A linear discriminant analysis (LDA) was used to estimate the contribution of polyunsaturated fatty acids (PUFA) derived from various potential sources to the coral hosts. The total fatty acid composition and fatty acid indices revealed differences between the more heterotrophic (P. verrucosa) and more autotrophic (P. speciosa) coral hosts, with the coral host G. fascicularis showing overlap with the other two species and greater variability overall. For the more heterotrophic P. verrucosa, the fatty acid indices and LDA results both indicated a greater proportion of copepod-derived fatty acids compared to the other coral species. Overall, the LDA estimated that PUFA derived from particulate resources (e.g., copepods and diatoms) comprised a greater proportion of coral host PUFA in contrast to the lower proportion of symbiont-derived PUFA. These estimates provide insight into the importance of heterotrophy in coral nutrition, especially in productive reef systems. The study supports carbon stable isotope results and demonstrates the utility of fatty acid analyses for exploring the trophic strategies of reef-building corals.

Probiotic properties and fatty acid composition of the yeast Kluyveromyces lactis M3. In vivo immunomodulatory activities in gilthead seabream (Sparus aurata)

The aim of this study was to analyze the probiotic potential, fatty acid composition and immunostimulant activities of Kluyveromyces lactis M3 isolated from a hypersaline sediment. For this purpose, K. lactis M3 resistance to different pH, salinities and bile, as well as its antioxidant capability were assayed. Furthermore, total fatty acid composition of the yeast was determined where the dominant fatty acids were palmitic, palmitoleic, oleic and linoleic acids. K. lactis M3 showed no cytotoxic effects on peripheral blood leukocytes. During an in vivo experiment in gilthead seabream (Sparus aurata), dietary K. lactis M3 supplemented at 0.55 or 1.1% of the basal diet enhanced bactericidal activity against Vibrio parahaemolyticus N16, V. harveyi Lg 16/00, and V. anguillarum CECT 43442 compared to fish fed commercial diet (control group). Finally, nitric oxide production, peroxidase activity and skin mucus lectin union levels strongly increased in fish fed K. lactis M3 with respect to the control group. The results suggested that the yeast K. lactis M3 had exhibited high antioxidant capability, and its dietary administration at 0.55 or 1% basal diet had immunostimulant activity for gilthead seabream. For all these reasons, it should be considered an appropriate probiotic candidate for the aquaculture fish industry.