Production Of Polyunsaturated Fatty Acids Research Articles

Enhancing the biosynthesis of polyunsaturated fatty acids by Rhodotorula mucilaginosa and Lodderomyces elongisporus

Single-cell oils (SCO) produced by oleaginous yeast hold promise as a sustainable alternative for producing nutritionally and pharmaceutically valuable lipids. However, the accumulation of oils varies substantially between yeast spp. Consequently, identifying well-suited producers with a high innate capacity for lipids biosynthesis is paramount. Equally important is optimizing culturing and processing conditions to realize the total lipids production potential of selected strains. The marine Rhodotorula mucilaginosa and Lodderomyces elongisporus yeast were investigated to explore their potential for polyunsaturated fatty acids (PUFAs) production on high glucose media (HGM) using two-stage culture mode. Both strains accumulated > 20% (w/w) of their dry cell weight as lipids when grown on HGM using a two-stage culture system. Both yeast isolates exhibited a maximal lipid/biomass coefficient (YL/X) of 0.58–0.66 mg/mg at 7 °C and 0.49–0.53 mg/mg at 26 °C when grown on 8% glucose and produced monounsaturated and PUFAs similar to that of Menhaden and Salmon marine oils. For the first time, significant amounts of Eicosapentaenoic acid (19%) and Eicosadienoic acid (19.6%) were produced by L. elongisporus and R. mucilaginosa, respectively. Thus, the SCO derived from these wild strains possesses significant potential as a substitute source for the industrial-scale production of long-chain PUFAs, making them a promising contender in the market.Graphical

Investigation of Crypthecodinium cohnii High-Cell-Density Fed-Batch Cultivations

Crypthecodinium cohnii is a marine microalga that can accumulate high amounts of polyunsaturated fatty acids (PUFAs) and thus replace conventional routes of fish oil production. They are associated with the destruction of marine resources and multiple downstream/purification complications. The major drawbacks of using C. cohnii for industrial-scale production are associated with low PUFA productivity. One of the means of increasing the PUFA synthesis rate is to maintain the medium component concentrations at optimal values throughout cultivation, thus increasing PUFA production efficiency, which can result in the successful transfer of the process to pilot and/or industrial scale. The goal of the present research was to develop techniques for increasing the efficiency of PUFA production via C. cohnii cultivation. Multiple experiments were carried out to test and fine-tune the cultivation medium composition and oxygen transfer factors. The biomass yields from individual components, yeast extract, sea salts, and glucose amounted to 5.5, 0.65, and 0.61 g·g−1, respectively. C. cohnii cell susceptibility to mechanical damage was experimentally evaluated. Power inputs of <276.5 W/m3 did not seem to promote cell destruction when Pitched-blade impellers were used. The obtained cultivation conditions were shown to be efficient in terms of increasing the biomass productivity and the omega-3 fatty acid content in C. cohnii. By using the applied methods, the maximal biomass productivity reached 8.0 g·L−1·day−1, while the highest obtained biomass concentration reached 110 g·L−1. A steady increase in the concentration of PUFAs during cultivation was observed from the FTIR data.

Metal-phenolic nanocatalyst rewires metabolic vulnerability for catalytically amplified ferroptosis

Ferroptosis is associated with excessive lipid peroxidation (LPO) accumulation, followed by membrane fragmentation. Although lipid metabolism is essential for regulating ferroptosis execution in tumors, there has been no use of nanomedicine to modulate the effect of metabolic vulnerability on ferroptosis. This study presents a metal-phenolic nanocatalyst (Fe@MT nanocatalyst), self-assembled using ferric ions (Fe3+) and coordinating with mitoxantrone (MT). This nanocatalyst accumulates lipid peroxides to strengthen ferroptotic vulnerability by initiating reactive oxygen species (ROS) storm and remodeling polyunsaturated fatty acids (PUFAs)-containing lipid metabolism. Fe@MT nanocatalyst catalytically converts endogenous hydrogen peroxide into highly active hydroxyl radical and depletes high intracellular levels of glutathione upon its internalization by U87MG cells, resulting in the release of MT, which in return promotes irreversible ferroptosis by elevating the intracellular production of ROS-sensitive PUFAs and inducing lethal LPO. Fe@MT nanocatalyst exhibits near-infrared photothermal property because of Fe3+ and MT self-assembly, causing photothermal-amplified catalytic ferroptosis therapy. This study sheds new light on promoting the sensitivity and execution of ferroptosis by reinforcing lethal lipid metabolism and accumulating excessive LPO and will establish an exploitable interaction between ferroptosis and lipid metabolic vulnerability in cancer.

Assessment of heavy metals and environmental stress conditions on the production potential of polyunsaturated fatty acids (PUFAs) in indigenous microalgae isolated from the Gulf of Mannar coastal waters.

The present study evaluated the effects of heavy metals, viz., lead, mercury, and cadmium, on growth, chlorophyll a, b, c, carotenoids, and PUFA content of marine microalgae Chlorella sp. and Cylindrotheca fusiformis. At 96-h exposure, the IC50 values for Hg2+, Pb2+, and Cd2+ were 0.85mg/L, 2.4mg/L, and 5.3mg/L respectively, in Chlorella sp. In C. fusiformis, IC50 values for Hg2+, Pb2+, and Cd2+ were 0.5mg/L, 1.2mg/L, and 3mg/L respectively. The pigment contents of both microalgae were significantly affected upon heavy metal exposure. In Chlorella sp. and C. fusiformis, the exposed concentrations of Hg2+ averagely decreased the PUFA content by 76.34% and 78.68%, respectively. Similarly, Pb2+-exposed concentrations resulted in 54.50% and 82.64% average reductions in PUFA content of Chlorella sp. and C. fusiformis, respectively. Cd2+-exposed concentrations showed 32.58% and 40.54% average reduction in PUFA content of Chlorella sp. and C. fusiformis, respectively. Among the environmental stress conditions, the dark treatment has increased total PUFA content by 6.63% in Chlorella sp. and 3.92% in C. fusiformis. It was observed that the 50% nitrogen starvation (two-stage) significantly improved the PUFA production from 26.47 ± 6.55% to 40.92 ± 10.74% in Chlorella sp. and from 11.23 ± 5.01 to 32.8 ± 14.17% in C. fusiformis. The toxicity for both microalgae was followed in the order Hg2+ > Pb2+ > Cd2+. Among the two species, Chlorella sp. has shown a high tolerance to heavy metals and can be effectively utilized in PUFA production.

Production of polyunsaturated fatty acids in pork backfat fermented by Mucor circinelloides

Pork backfat (PB) contains excessive saturated fatty acids (SFAs), but lacks polyunsaturated fatty acids (PUFAs). Excessive SFAs can be used as a substrate for the growth of certain microorganisms that convert them into PUFAs and monounsaturated fatty acids (MUFAs), and the added value of PB can be enhanced. In this study, Mucor circinelloides CBS 277.49 and Lactiplantacillus plantarum CGMCC 24189 were co-cultured for conversion of PB into fermented pork backfat (FPB) with high level of PUFAs. Our results showed that the content of γ-linolenic acid (GLA) and linoleic acid (LA) in the surface of FPB reached 9.04 ± 0.14 mg/g and 107.31 ± 5.16 mg/g for 7-day fermentation, respectively. To convert the internal SFAs of PB, ultrasound combined with papain was used to promote the penetrative growth of M. circinelloides into the internal PB, and the GLA level in the third layer of fat reached 2.58 ± 0.31 mg/g FPB. The internal growth of M. circinelloides in PB was promoted by adjusting the oxygen rate and ventilation rate through the wind velocity sensor. When the oxygen rate is 2 m/s and the ventilation rate is 18 m3/h, the GLA level in the third layer of fat reached 4.13 ± 1.01 mg/g FPB. To further improve the level of PUFAs in PB, FPB was produced by M. circinelloides at 18 °C. The GLA content on the surface of FPB reached 15.73 ± 1.13 mg/g FPB, and the GLA yield in the second and third layers of fat reached 8.68 ± 1.77 mg/g FPB and 6.13 ± 1.28 mg/g FPB, the LA yield in the second and third layers of fat reached 105.45 ± 5.01 mg/g FPB and 98.46 ± 4.14 mg/g FPB, respectively. These results suggested that excessive SFAs in PB can be converted into PUFAs and provided a new technique for improving PUFAs in FPB.Key points• This article achieved the conversion of PUFAs in pork backfat by Mucor circinelloides CBS 277.49 and Lactiplantacillus plantarum CGMCC 24189.• This article solved the internal growth of M. circinelloides CBS277.49 in pork backfat by ultrasound combined with papain.• This article proposed an innovative of promoting the internal growth of M. circinelloides and increasing the PUFAs production by oxygen ventilation in pork backfat.

Characterization of Three Types of Elongases from Different Fungi and Site-Directed Mutagenesis.

Fatty acid elongases play crucial roles in synthesizing long-chain polyunsaturated fatty acids. Identifying more efficient elongases is essential for enhancing oleaginous microorganisms to produce high yields of target products. We characterized three elongases that were identified with distinct specificities: McELO from Mucor circinelloides, PrELO from Phytophthora ramorum, and PsELO from Phytophthora sojae. Heterologous expression in Saccharomyces cerevisiae showed that McELO preferentially elongates C16 to C18 fatty acids, PrELO targets Δ6 polyunsaturated fatty acids, and PsELO uses long chain saturated fatty acids as substrates. McELO and PrELO exhibited more homology, potentially enabling fatty acid composition remodeling and enhanced LC-PUFAs production in oleaginous microorganisms. Site-directed mutagenesis of conserved amino acids across elongase types identified residues essential for activity, supported by molecular docking. Alanine substitution of conserved polar residues led to enzyme inactivation, underscoring their importance in the condensation reaction. Our findings offer promising elongase candidates for polyunsaturated fatty acid production, contributing to the bioindustry's sustainable development.

Screening for the production of polyunsaturated fatty acids and cerebrosides in fungi.

To investigate fatty acid, including polyunsaturated fatty acids (PUFA), and cerebroside production of a large diversity of fungi from the Ascomycota, Basidiomycota, and Mucoromycota phyla. Seventy-nine fungal strains were grown in Kavadia medium using a microcultivation system, i.e. Duetz microtiter plates. Following cultivation, fatty acid and cerebroside contents were analyzed by gas chromatography-flame ionization detection (GC-FID) and high performance thin-layer chromatography (HPTLC), respectively. Mucoromycota fungi appeared as the most promising candidates for omega-6 PUFA production. The best omega-6 producer, including γ-linolenic acid (GLA, 18:3n-6), was Mucor fragilis UBOCC-A109196 with a concentration of 647mg L-1 total omega-6 PUFA (representing 35% of total fatty acids) and 225mg L-1 GLA (representing 12% of total fatty acids). Arachidonic acid concentration (20:4n-6) was the highest in Mortierella alpina UBOCC-A-112046, reaching 255mg L-1 and 18.56% of total fatty acids. Interestingly, several fungal strains were shown to produce omega-7 monounsaturated fatty acids. Indeed, Torulaspora delbrueckii strains accumulated palmitoleic acid (16:1n-7) up to 20% of total fatty acids, reaching 114mg L-1 in T. delbrueckii UBOCC-A-214128, while C. elegans UBOCC-A-102008 produced mainly paullinic acid (20:1n-7) with concentrations up to 100mg L-1. Concerning cerebroside production, HPTLC appeared as a relevant approach for their detection and quantification. Promising candidates belonging to the Mucoromycota phylum were found, especially in the Absidia genus with A. spinosa UBOCC-A-101332 as the best producer (12.7mg L-1). The present study highlighted PUFA and cerebroside production in a large diversity of fungi and the fact that members of the Mucoromycota phylum are good producers of PUFA as well as cerebrosides.

Recycling Fermentation Strategy for Waste Cellular Residues in the Production of Polyunsaturated Fatty Acids

Cellular residues after lipid extraction are the primary waste by-products of microbial polyunsaturated fatty acid production. To mitigate the discharge of cellular residues and reduce the cost of DHA and ARA production, this study examined the utilization of enzymatically hydrolyzed Aurantiochytrium cellular residues (ACRs) and Mortierella alpina cellular residues (MCRs) as nitrogen sources. Results demonstrated that ACRs and MCRs could partially substitute yeast extract (YE) without adverse effects on DHA and ARA fermentation. Moreover, the implementation of a new fermentation medium incorporating ACRs, MCRs, and YE as mixed nitrogen sources resulted in DHA and ARA yields of 17.78 and 5.77 g/L, respectively. These values represented increases of 10.37% and 9.28% compared to traditional cultural methods, while simultaneously reducing the usage of YE by 80% and 60%, respectively. Therefore, the strategy of recycling waste cellular residues presents a novel approach for reducing the costs and environmental impact associated with microbial fermentations.

Evaluation of meat and meat product oxidation and off-flavor formation: Managing oxidative changes

One of the primary issues with processed foods during heat treatment and freezing storage is fat oxidation, which causes significant changes in fats due to their interaction with reactive oxygen species (ROS). This interaction leads to the creation of various aldehydes that have a high affinity for large molecules, such as proteins, leading to the formation of final products of advanced oxidation processes that contribute to food spoilage. Co-oxidation can also result in extensive damage. Another problem affecting the quality and nutritional value of meat products is protein oxidation, which can occur during storage via freezing and thawing or as a result of heat treatment. Heat treatment can cause physical and chemical changes, such as the loss of some essential amino acids and the transformation of certain amino acids into carbonyl compounds via various mechanisms. Protein oxidation is indicated by the accumulation of these carbonyl compounds, and the heat treatment can lead to the denaturation of myoglobin, which is responsible for the brown color of cooked meat and is influenced by several factors. Active protein aggregates can interact with the oxidation products of polyunsaturated fatty acids and with carbohydrate glycation or glycoxidation to produce Maillard products. It is critical to understand the oxidative changes that occur in fats and proteins in food, particularly in meat products, since these components are among the primary constituents of food.

Fine-tuning of key parameters to enhance biomass and nutritional polyunsaturated fatty acids production from Thraustochytrium sp.

The escalating demand for long-chain polyunsaturated fatty acids (PUFAs) due to their vital health effects has deepened the exploration of sustainable sources. Thraustochytrium sp. stands out as a promising platform for omega-3 and 6 PUFA production. This research strategically optimizes key parameters: temperature, salinity, pH, and G:Y:P ratio and the optimized conditions for maximum biomass, total lipid, and DHA enhancement were 28 °C, 50 %, 6, and 10:1:2 respectively. Process optimization enhanced 32.30 and 31.92 % biomass (9.88 g/L) and lipid (6.57 g/L) yield. Notably, DHA concentration experienced a substantial rise of 69.91 % (1.63 g/L), accompanied by notable increases in EPA and DPA by 82.69 % and 31.47 %, respectively. MANOVA analysis underscored the statistical significance of the optimization process (p < 0.01), with all environmental factors significantly influencing biomass and lipid data (p < 0.05), particularly impacting DHA production. Thraustochytrium sp. can be a potential source of commercial DHA production with the fine-tuning of these key process parameters.

Development of user-friendly protocols for single-cell arachidonic acid production in developing countries

Arachidonic acid (ARA) is a sorely needed nutrient and an effective and safe schistosomicide and tumoricide. Consumption levels are low in developing countries because of unawareness of its critical impact on health and limited commercial availability. The research work aims to encourage production in developing countries via providing user-friendly definitive protocols for polyunsaturated fatty acids production by the fungus Mortierella alpina and ARA isolation. Fatty acids content was determined by gas chromatography-flame ionization detector. The optimal cultivation conditions included culture medium to flask volume 1:5; shake-flask culture at 25 °C, then at 20 °C, and stationary aging at 10 °C, each over 7 days, while addition of trace minerals and vitamins was dispensable. The ARA yield attained >1.8 g per liter culture. Repeat experiments led to the selection of an optimal lipid extraction method from dried biomass, and efficacious urea complexation-based protocol for obtention of high ARA yield and purity.

Microbial Fermentation of the Water-Soluble Fraction of Brewers’ Spent Grain for the Production of High-Value Fatty Acids

Brewers’ spent grain (BSG) constitutes the primary by-product of the brewing industry. The valorization of BSG from a circular economy perspective is of high industrial interest. The objective of this study was the exploitation of BSG for the microbial production of branched-chain fatty acids (BCFAs) and polyunsaturated fatty acids (PUFAs), representing two different classes of high-value fatty acids (FAs). In the present study, this waste material underwent treatment with hot water in an autoclave and the resultant extract was utilized for the preparation of a novel liquid medium (BSG medium) to be employed for microbial fermentation. Screening and subsequent scaling-up experiments confirmed the suitability of the BSG medium to support the microbial production of various high-value FAs. In particular, Streptomyces jeddahensis and Conidiobolus heterosporus could be employed for BCFAs production, Pythium ultimum and Mortierella alpina could be used to provide cis-5,8,11,14,17-eicosapentaenoic acid (EPA) and arachidonic acid (ARA), whereas Mucor circinelloides, when grown in a BSG medium, was able to accumulate γ-linolenic acid (GLA).

Application of ANN-MOGA for nutrient sequestration for wastewater remediation and production of polyunsaturated fatty acid (PUFA) by Chlorella sorokiniana MSP1

Chlorella bears excellent potential in removing nutrients from industrial wastewater and lipid production enriched with polyunsaturated fatty acids. However, due to the changing nutrient dynamics of wastewater, growth and metabolic activity of Chlorella are affected. In order to sustain microalgal growth in wastewater with concomitant production of PUFA rich lipids, RSM (Response Surface Methodology) followed by heuristic hybrid computation model ANN-MOGA (Artificial Neural Network- Multi-Objective Genetic Algorithm) were implemented. Preliminary experiments conducted taking one factor at a time and design matrix of RSM with process variables viz. Sodium chloride (1 mM–40 mM), Magnesium sulphate (100 mg–800 mg) and incubation time (4th day to 20th day) were validated by ANN-MOGA. The study reported improved biomass and lipid yield by 54.25% and 12.76%, along with total nitrogen and phosphorus removal by 21.92% and 18.72% respectively using ANN-MOGA. It was evident from FAME results that there was a significantly improved concentration of linoleic acid (19.1%) and γ-linolenic acid (21.1%). Improved PUFA content makes it a potential feedstock with application in cosmeceutical, pharmaceutical and nutraceutical industry. The study further proves that C. sorokiniana MSP1 mediated industrial wastewater treatment with PUFA production is an effective way in providing environmental benefits along with value addition. Moreover, ANN-MOGA is a relevant tool that could control microalgal growth in wastewater.

Effects of sunflower oil infusions of Asparagopsis taxiformis on in vitro ruminal methane production and biohydrogenation of polyunsaturated fatty acids

Asparagopsis taxiformis inhibits ruminal methane (CH4) production due to its bromoform (CHBr3) content. The immersion of A. taxiformis in edible vegetable oils allows the extraction and stabilization of the highly volatile CHBr3 in the oil phase. The objectives of this study were to explore the effects of adding sunflower oils with increasing concentrations of CHBr3 on in vitro ruminal methanogenesis and biohydrogenation. Five batches of 48-h in vitro incubations were performed in 14 fermentation bottles, using rumen inocula collected shortly after the slaughter of young crossbred bulls and 1 g of dry matter (DM) from a total diet of mixed feed without added oil (control) or with 60 μL of sunflower oil per gram of DM as the substrate. The treatments were the CHBr3 content in the oil added: 0 μg (B0), 25 μg (B25), 50 μg (B50), 75 μg (B75), 100 μg (B100), and 150 μg (B150) of CHBr3 per gram of substrate DM. Organic matter (OM) degradability, total gas, CH4, volatile fatty acids (VFA), long-chain fatty acids, and dimethyl acetals (DMA) were analyzed at the end of each incubation. Data were analyzed with a model considering the treatments as the fixed effect and the run as a random block and using orthogonal contrasts. Degradability of OM was higher in the control group and was unaffected by CHBr3 concentration. Total gas production per gram of degraded OM was unaffected by treatments and averaged 205 ± 29.8 mL/g. Methane (mL) production decreased linearly with increasing CHBr3 concentrations, with 33%, 47%, and 87% reductions for B75, B100, and B150, respectively. Total VFA concentration was unaffected by oil inclusion but was reduced by 20% in CHBr3-containing treatments, although without any dose-response pattern. The molar percentage of acetate decreased linearly, whereas propionate and butyrate increased linearly with the increasing CHBr3 dosage. Including oil in the diet decreased the branched-chain fatty acids and DMA content. Increasing CHBr3 concentrations did not affect branched-chain fatty acids, but linearly increased most of the identified DMA. Adding oil to the control diet increased the 18:2n-6, whereas increasing the concentration of CHBr3 had no effect on 18:2n-6 but decreased linearly the 18:0 and increased the trans-18:1 isomers. The results obtained provide evidence that oil immersions of A. taxiformis can successfully inhibit ruminal production of CH4 in vitro at doses of 100 and 150 μg/g DM, and simultaneously modulate biohydrogenation.

Refactoring the architecture of a polyketide gene cluster enhances docosahexaenoic acid production in Yarrowia lipolytica through improved expression and genetic stability

BackgroundLong-chain polyunsaturated fatty acids (LC-PUFAs), such as docosahexaenoic acid (DHA), are essential for human health and have been widely used in the food and pharmaceutical industries. However, the limited availability of natural sources, such as oily fish, has led to the pursuit of microbial production as a promising alternative. Yarrowia lipolytica can produce various PUFAs via genetic modification. A recent study upgraded Y. lipolytica for DHA production by expressing a four-gene cluster encoding a myxobacterial PKS-like PUFA synthase, reducing the demand for redox power. However, the genetic architecture of gene expression in Y. lipolytica is complex and involves various control elements, offering space for additional improvement of DHA production. This study was designed to optimize the expression of the PUFA cluster using a modular cloning approach.ResultsExpression of the monocistronic cluster with each gene under the control of the constitutive TEF promoter led to low-level DHA production. By using the minLEU2 promoter instead and incorporating additional upstream activating UAS1B4 sequences, 5' promoter introns, and intergenic spacers, DHA production was increased by 16-fold. The producers remained stable over 185 h of cultivation. Beneficially, the different genetic control elements acted synergistically: UAS1B elements generally increased expression, while the intron caused gene-specific effects. Mutants with UAS1B16 sequences within 2–8 kb distance, however, were found to be genetically unstable, which limited production performance over time, suggesting the avoidance of long repetitive sequence blocks in synthetic multigene clusters and careful monitoring of genetic stability in producing strains.ConclusionsOverall, the results demonstrate the effectiveness of synthetic heterologous gene clusters to drive DHA production in Y. lipolytica. The combinatorial exploration of different genetic control elements allowed the optimization of DHA production. These findings have important implications for developing Y. lipolytica strains for the industrial-scale production of valuable polyunsaturated fatty acids.

Engineering a marine microalga Chlorella sp. as the cell factory

The use of marine microalgae in industrial systems is attractive for converting CO2 into value-added products using saline water and sunlight. The plant nature and demonstrated industrial potential facilitate Chlorella spp. as excellent model organisms for both basic research and commercial application. However, the transformation method has not been developed in marine Chlorella spp., thus genetic engineering is hindered in exploiting the industrial potentialities of these strains. In this study, we provided a transformation protocol for the marine Chlorella strain MEM25, which showed robust characteristics, including high production of proteins and polyunsaturated fatty acids in multiple cultivation systems over various spatial–temporal scales. We showed that transformants could be obtained in a dramatically time-saving manner (comparable to Saccharomyces cerevisiae) with four functional proteins expressed properly. The transgenes are integrated into the genome and can be successfully inherited for more than two years. The development of a marine Chlorella transformation method, in combination with the complete genome, will greatly facilitate more comprehensive mechanism studies and provide possibilities to use this species as chassis for synthetic biology to produce value-added compounds with mutual advantage in neutralization of CO2 in commercial scales.

Natural and recombinant bioactive compounds from Schizochytrium sp.: Recent advances and future prospects

Schizochytrium sp. is a unicellular heterotrophic marine protist, with global distribution used at an industrial scale for saturated fatty acid and polyunsaturated fatty acid production. Diverse methodologies for the genetic transformation of Schizochytrium sp. have been developed to express heterologous proteins, such as through Agrobacterium tumefaciens and electroporation. Culture optimization has been pursued using the nitrogen starvation strategy that shifts the metabolism of Schizochytrium sp. to lipid production, but the over-compensation has been demonstrated could improve biomass and protein biosynthesis. This review paper discusses several studies focused on maximizing the production of high-valued bioproducts, highlighting culture media optimization and genetic/metabolic engineering in Schizochytrium sp. with a biorefinery approach for biopharmaceutical and recombinant protein production.

Arctic Sea Ice Microalga Chlamydomonas latifrons KNF0041: Identification and Statistical Optimization of Medium for Enhanced Biomass and Omega-3/Omega-6.

Polar microorganisms produce biologically active compounds that enable them to survive in harsh environments. These compounds have potential biomedical applications. The green microalga Chlamydomonas latifrons KNF0041, isolated from Arctic sea ice, has been found to produce polyunsaturated fatty acids (PUFAs), including omega-3 and omega-6, which have antioxidant properties. To improve the biomass production of strain KNF0041, statistical methods such as the Plackett-Burman design, Box-Behnken design, and response surface methodology (RSM) were utilized for medium optimization. The optimized medium was designed with increased potassium phosphate content and reduced acetic acid (AcOH) content. The use of the optimized medium resulted in an increase in the cell number as biomass of strain KNF0041 by 34.18% and the omega-3 and omega-6 fatty acid (FA) content by 10.04% and 58.29%, respectively, compared to that in normal TAP medium, which is known as the growth medium for Chlamydomonas culture. In this study, Chlamydomonas latifrons was discovered for the first time in the polar region and identified using morphology and molecular phylogenetic analyses, the secondary structures of the internal transcribed spacers, and optimized culture conditions. The results of this study provide an efficient method for the application of polar microalgae for the production of bioactive compounds.

Draft genome sequence of a docosahexaenoic-acid-producing marine protist, thraustochytrid strain 12B.

We sequenced the draft genome of thraustochytrid strain 12B. This strain shows a high production of polyunsaturated fatty acids, such as docosahexaenoic acid. The draft genome sequence of approximately 65 Mbp will provide insights into metabolic engineering to improve the production of polyunsaturated fatty acids in the microorganism.

From viral load to survival: Unveiling new genetic links for resistance against PMCV in Atlantic Salmon (Salmo salar).

The infectious agent piscine myocarditis virus (PMCV) causes cardiomyopathy syndrome (CMS) and is responsible for substantial mortality and economic losses in the Atlantic salmon (Salmo salar) farming industry. Previous research has demonstrated that breeding for resistance against PMCV is an effective approach to mitigate the disease's impact. In this study, a new quantitative trait locus (QTL) is described on chromosome 23, together with previously described QTLs on chromosomes 12 and 27. The findings are based on two genome-wide association studies conducted on two different year-classes of Atlantic salmon of the Rauma strain. In this study, we utilized data from an experimental challenge trial with the viral load as the phenotype and a field outbreak of CMS with survival data as the phenotype. The estimated SNP-based heritability was 0.55 and 0.44 in the two studies, respectively. In the infection trial, the top associated SNP on chromosome 23 accounted for approximately 46% of the genetic and 25.53% of the phenotypic variations in the viral load. In the field outbreak, we identified a QTL on the same genomic region of chromosome 23. The most significantly associated marker on this chromosome explained 13.57% and 5.97% of the genetic and phenotypic variations. The QTL on chromosome 23 is in proximity to delta-5 fatty acyl desaturase and fatty acid desaturase 2 genes, both of which play a role in the production of polyunsaturated fatty acids. This proximity is particularly interesting as it offers valuable insights into enhancing our understanding of resistance against PMCV.