Climate change and n-3 LC-PUFA availability

The impact of climate change on Omega-3 long-chain polyunsaturated fatty acids in bivalves

Omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA) have many health benefits to human. Increasing evidence have shown that climate change reduces the availability of plankton n-3 LC-PUFA to primary consumers which potentially reduces the availability of n-3 LC-PUFA to human. Since marine bivalves are an important source of n-3 LC-PUFA for human beings, and bivalve aquaculture completely depends on phytoplankton in ambient water as food, it is important to understand the impact of climate change on the lipid nutritional quality of bivalves. In this study, fatty acid profile of different bivalves (mussels, oysters, clams, scallops and cockles) from different regions (tropical, subtropical and temperate) and time (before 1990, 1991-1995, 1996-2000, 2001-2005, 2006-2010, 2011-2015, 2016-2020) were extracted from published literature to calculate various lipid nutritional quality indicators. The results of this study revealed that the effects of global warming and declines in aragonite saturation state on the lipid content and lipid indices of bivalves are highly dependent on the geographical region and bivalves. In general, global warming has the largest negative impact on the lipid content and indices of temperate bivalves, including decreasing the PUFA/SFA, EPA + DHA and n-3/n-6. However, global warming has a much smaller negative impact on lipid content and lipid indices in other regions. The declines of aragonite saturation state in seawater promotes the accumulation of lipid content in tropical and subtropical bivalves, but it compromised the PUFA/SFA, EPA + DHA and n-3/n-6 of bivalves in all regions. The findings of this study not only fill the knowledge gap of the impact of climate change on the lipid nutritional quality of bivalves, but also provide guidance for the establishment of bivalve aquaculture and fisheries management plans to mitigate the impact of climate change.

Current upstream and downstream process strategies for sustainable yeast lipid production

An increasing global population demands more lipids for food and chemicals, but the unsustainable growth of plant-derived lipid production and an unreliable supply of certain lipids due to environmental changes, require new solutions. One promising solution is the use of lipids derived from microbial biomass, particularly oleaginous yeasts. This critical review begins with a description of the most promising yeast lipid replacement targets: palm oil substitute, cocoa butter equivalent, polyunsaturated fatty acid source, and animal fat analogue, emphasizing sustainability aspects. Subsequently, the review focuses on the most recent advances in upstream methodologies, particularly fermentation strategies that promote circularity, such as waste valorisation, co-cultivation and co-product biosynthesis. Downstream processing methods for minimising energy consumption and waste generation, including bioflocculation, energy-efficient and environmentally friendly cell lysis and extraction, and integrated co-product recovery methods, are discussed. Finally, the current challenges are outlined. Integrating these strategies advances sustainable yeast lipid production for high-value applications.

Delta-5 elongase knockout reduces docosahexaenoic acid and lipid synthesis and increases heat sensitivity in a diatom

Recent global marine lipidomic analysis reveals a strong relationship between ocean temperature and phytoplanktonic abundance of omega-3 long-chain polyunsaturated fatty acids, especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which are essential for human nutrition and primarily sourced from phytoplankton in marine food webs. In phytoplanktonic organisms, EPA may play a major role in regulating the phase transition temperature of membranes, while the function of DHA remains unexplored. In the oleaginous diatom Phaeodactylum tricornutum, DHA is distributed mainly on extraplastidial phospholipids, which is very different from the EPA enriched in thylakoid lipids. Here, clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9-mediated knockout of delta-5 elongase (ptELO5a), which encodes a delta-5 elongase (ELO5) catalyzing the elongation of EPA to synthesize DHA, led to a substantial interruption of DHA synthesis in P. tricornutum. The ptELO5a mutants showed some alterations in transcriptome and glycerolipidomes, including membrane lipids and triacylglycerols under normal temperature (22 °C), and were more sensitive to elevated temperature (28 °C) than wild type. We conclude that PtELO5a-mediated synthesis of small amounts of DHA has indispensable functions in regulating membrane lipids, indirectly contributing to storage lipid accumulation, and maintaining thermomorphogenesis in P. tricornutum. This study also highlights the significance of DHA synthesis and lipid composition for environmental adaptation of P. tricornutum.

The effects of bivalve aquaculture on carbon storage in the water column and sediment of aquaculture areas

Many researchers have evaluated the fishery carbon sink potential of bivalve aquaculture, with most studies focusing on the Life Cycle Assessment (LCA) of individual bivalves, and there is currently no consensus on whether bivalves are carbon sinks or carbon sources. It is worth noting that most studies have not considered the impact of bivalve aquaculture on ecosystems when evaluating its carbon sink potential. In this context, based on existing literature, this article aims to comprehensively review the effects of bivalve aquaculture on carbon storage in the water column and sediment of aquaculture areas. In general, our findings revealed that moderate and low stocking densities of bivalve aquaculture do not lead to significant changes in the abundance of phytoplankton, but it does indeed alter the phytoplankton community structure from dominated by huge diatom with lower carbon densities to dominated by small phytoplankton with higher carbon densities. Therefore, bivalve aquaculture may increase the total carbon storage in the water column. In addition, bivalve aquaculture also increases the sedimentation rate of suspended particles, increasing the rate of carbon burial, especially in low-energy environment and shallow water areas. The findings of this article fill the knowledge gap of fishery carbon sink in bivalve aquaculture from an ecosystem perspective.

Protein quality of commercially important edible bivalves

Bivalves are a high-quality source of animal protein for human consumption. In recent years, the demand for bivalve proteins has increased dramatically, leading to a sharp increase in global production of marine bivalves. To date, although the amino acid profiles of many bivalves have been reported, such information has not been well organized. Therefore, there is an urgent need for a comprehensive scientific review of the protein quality of bivalves, especially commercially important edible bivalves. In this context, this study was conducted to evaluate the protein quality of commercially important edible bivalves. In general, most bivalves are rich in protein (> 50% of their dry weight) and amino acids (> 30 g/100g protein). Although most species of bivalves are rich in essential amino acids (EAA) (up to 50 g/100g protein), some species of edible bivalves have very low levels of EAA (< 5 g/100g protein). Based on the AA score, almost all bivalves have at least two limiting AAs. Most bivalve proteins provides delicious flavors with unami, sweetness and a hint of bitterness. The findings of this study not only serve as a a guide for selecting appropriate bivalves based on consumer preferences for specific AAs or AA scores, but also provide information on potential bivalve species for aquaculture to produce higher protein quality to meet the growing demand for high quality animal protein.

Impact of Climate Change on Dietary Nutritional Quality and Implications for Asthma and Allergy

Asthma and allergic disorders are common in childhood with genetic and environmental determinants of disease that include prenatal nutritional exposures such as long-chain polyunsaturated fatty acids and antioxidants. Global climate change is implicated in asthma and allergic disorder morbidity with potential mechanisms including perturbations of ecosystems. There is support that environmental and climatic changes such as increasing global temperate and carbon dioxide levels affect aquatic and agricultural ecosystems with subsequent alterations in long-chain polyunsaturated fatty acid availability and nutrient quality and antioxidant capacity of certain crops, respectively. This article discusses asthma epidemiology and the influence of global climate change.

Effect of climate change on fillet quality and shelf-life of Oncorhynchus mykiss under controlled conditions

BACKGROUND

Temperature, which affects numerous physiological processes, has been described as the 'main ecological factor' for fish. The aim of this modeling study is to explore the impact of climate-induced temperature changes on fish fillet quality and shelf life.

RESULTS

Temperature stress in rainbow trout affected ash and moisture, and inhibited myofibril fragmentation in the fillets. However, with the increase in temperature, there was a decrease in the total amount of saturated fatty acids (∑SFA) and there were significant increases in the total amount of omega 3 (∑n3) and 22:6n-3 (DHA). It was determined that temperature increase had a negative effect on color, texture, water-holding capacity, water activity, pH, lactic acid, and glycogen levels in fillets, and it had a positive effect by delaying microbial spoilage, especially in cold storage.

CONCLUSION

This study suggest that the effects of climate change on product quality and shelf life in fish requires further research. It highlights knowledge gaps to guide future research in this emerging field. © 2023 Society of Chemical Industry.

The impact of elevated temperature on the macro-nutrients of commercially important marine bivalves: the implication of ocean warming

Bivalves are nutritious animal protein source for humans, rich in high quality proteins, lipids, and carbohydrates. Many studies have shown that ocean warming has detrimental effects on the nutritional quality of bivalves. Although a number of studies are available on the effect of ocean warming on the nutritional value of bivalves, this information is not well organized. In this context, the current study provides a critical review of the effects of ocean warming on the nutritional quality of commercially important edible marine bivalves. In general, ocean warming has caused a reduction in the total lipid and carbohydrate content of bivalves, especially those bivalves inhabiting temperate regions. As for protein, there is no general trend in the effects of ocean warming on the protein reserves of bivalves. In addition, the specific effects of elevated temperature on the macro-nutrients of bivalves highly depend on the tissues, sex and developmental stages of bivalves, as well as seasonal factors. This review not only fills in the knowledge gap regarding the effects of elevated temperature on the macro-nutrients of commercially important marine bivalves but also provides guidance for the establishment of bivalve aquaculture and fisheries management plans to mitigate the impact of climate change.

Effects of culinary treatments on the lipid nutritional quality of fish and shellfish

Coronary heart disease (CHD) is one of the leading causes of death worldwide. Seafood, especially fish and shellfish, is a healthy food that reduces the risk of CHD. In many regions, seafood is consumed cooked to eliminate potentially pathogenic microorganisms. Although there have been many reports of culinary preparations causing changes in the fatty acid profile of fish and shellfish, this information has not been well organized, and most of it is not associated to CHD. Therefore, this study was conducted to study the effect of culinary treatments of seafood on lipid nutritional quality in relation to promotion/prevention of CHD. In this study, fatty acid profiles of fish and shellfish prepared with different culinary preparations were obtained from published literature. Lipid nutritional quality indices related to promoting/preventing CHD were calculated and analyzed to reveal the effects of culinary treatment on the lipid nutritional quality of fish and shellfish in promoting/preventing of CHD. The information in this article is very useful and can fill the knowledge gap of the effects of culinary preparation on the lipid nutritional quality of fish and shellfish. Such information is very useful for guiding consumers to choose better ways to cook fish and shellfish to reduce the risk of CHD.

Bioproduction of n-3 polyunsaturated fatty acids by nematode fatty acid desaturases and elongase in Drosophila melanogaster

n-3 polyunsaturated fatty acids (n-3 PUFAs), including α-linolenic acid and eicosapentaenoic acid (EPA), are essential nutrients for vertebrates including humans. Vertebrates are n-3 PUFA-auxotrophic; hence, dietary intake of n-3 PUFAs is required for their normal physiology and development. Although fish meal and oil have been utilized as primary sources of n-3 PUFAs by humans and aquaculture, these traditional n-3 PUFA sources are expected to be exhausted because of the increasing consumption requirements of humans. Hence, it is necessary to establish alternative n-3 PUFA sources to reduce the gap between the supply and demand of n-3 PUFAs. Here, we investigated whether insects, which are considered as a novel source of essential nutrients, could store n-3 PUFAs by the forced expression of n-3 PUFA biosynthetic enzymes. We utilized Drosophila as an insect model to generate transgenic strains expressing Caenorhabditis elegans PUFA biosynthetic enzymes and examined their effects on the proportion of fatty acids. The ubiquitous expression of methyl-end desaturase FAT-1 prominently enhanced the proportions of α-linolenic acid, indicating that FAT-1 is useful for metabolic engineering to fortify α-linolenic acid in insect. Furthermore, the ubiquitous expression of nematode front-end desaturases (FAT-3 and FAT-4), PUFA elongase (ELO-1), and FAT-1 led to EPA bioproduction. Hence, nematode PUFA biosynthetic genes may serve as powerful genetic tools for enhancing the proportion of EPA in insects. This study represents the first step toward the establishment of n-3 PUFA-producing insects.

Polyunsaturated Fatty Acids: Conversion to Lipid Mediators, Roles in Inflammatory Diseases and Dietary Sources

Polyunsaturated fatty acids (PUFAs) are important components of the diet of mammals. Their role was first established when the essential fatty acids (EFAs) linoleic acid and α-linolenic acid were discovered nearly a century ago. However, most of the biochemical and physiological actions of PUFAs rely on their conversion to 20C or 22C acids and subsequent metabolism to lipid mediators. As a generalisation, lipid mediators formed from n-6 PUFAs are pro-inflammatory while those from n-3 PUFAs are anti-inflammatory or neutral. Apart from the actions of the classic eicosanoids or docosanoids, many newly discovered compounds are described as Specialised Pro-resolving Mediators (SPMs) which have been proposed to have a role in resolving inflammatory conditions such as infections and preventing them from becoming chronic. In addition, a large group of molecules, termed isoprostanes, can be generated by free radical reactions and these too have powerful properties towards inflammation. The ultimate source of n-3 and n-6 PUFAs are photosynthetic organisms which contain Δ-12 and Δ-15 desaturases, which are almost exclusively absent from animals. Moreover, the EFAs consumed from plant food are in competition with each other for conversion to lipid mediators. Thus, the relative amounts of n-3 and n-6 PUFAs in the diet are important. Furthermore, the conversion of the EFAs to 20C and 22C PUFAs in mammals is rather poor. Thus, there has been much interest recently in the use of algae, many of which make substantial quantities of long-chain PUFAs or in manipulating oil crops to make such acids. This is especially important because fish oils, which are their main source in human diets, are becoming limited. In this review, the metabolic conversion of PUFAs into different lipid mediators is described. Then, the biological roles and molecular mechanisms of such mediators in inflammatory diseases are outlined. Finally, natural sources of PUFAs (including 20 or 22 carbon compounds) are detailed, as well as recent efforts to increase their production.

Effects of high temperature and marine heat waves on seagrasses: Is warming affecting the nutritional value of Posidonia oceanica?

Primary producers nutritional content affects the entire food web. Here, changes in nutritional value associated with temperature rise and the occurrence of marine heat waves (MHWs) were explored in the endemic Mediterranean seagrass Posidonia oceanica. The variability of fatty acids (FAs) composition and carbon (C) and nitrogen (N) content were examined during summer 2021 from five Mediterranean sites located at the same latitude but under different thermal environments. The results highlighted a decrease in unsaturated FAs and C/N ratio and an increase of monounsaturated FA (MUFA) and N content when a MHW occurred. By contrast, the leaf biochemical composition seems to be adapted to local water temperature since only few significant changes in MUFA were found and N and C/N had an opposite pattern compared to when a MHW occurs. The projected increase in temperature and frequency of MHW suggest future changes in the nutritional value and palatability of leaves.

Safeguarding nutrients from coral reefs under climate change

The sustainability of coral reef fisheries is jeopardized by complex and interacting socio-ecological stressors that undermine their contribution to food and nutrition security. Climate change has emerged as one of the key stressors threatening coral reefs and their fish-associated services. How fish nutrient concentrations respond to warming oceans remains unclear but these responses are probably affected by both direct (metabolism and trophodynamics) and indirect (habitat and species range shifts) effects. Climate-driven coral habitat loss can cause changes in fish abundance and biomass, revealing potential winners and losers among major fisheries targets that can be predicted using ecological indicators and biological traits. A critical next step is to extend research focused on the quantity of available food (fish biomass) to also consider its nutritional quality, which is relevant to progress in the fields of food security and malnutrition. Biological traits are robust predictors of fish nutrient content and thus potentially indicate how climate-driven changes are expected to impact nutrient availability within future food webs on coral reefs. Here, we outline future research priorities and an anticipatory framework towards sustainable reef fisheries contributing to nutrition-sensitive food systems in a warming ocean.

Brown seaweed hydrolysate as a promising growth substrate for biomass and lipid synthesis of the yeast yarrowia lipolytica

Biomass of the brown algae Fucus vesiculosus and Saccharina latissima is a promising, renewable feedstock because of the high growth rate, accessibility and content of glucose and mannitol. Saccharification of seaweeds is a simple process due to the lack of lignocellulose in the cell wall. The high content of glucose and mannitol makes these seaweeds an attractive feedstock for lipid production in the yeast Yarrowia lipolytica. This study demonstrated that hydrolysates of brown algae biomass can be applied as a substrate for synthesis of yeast biomass and lipids without any supplementation. To increase the lipid titer in yeast biomass, we employed an engineered strain of Y. lipolytica overexpressing DGA1/DGA2. In consequence, the C/N ratio has a lower impact on lipid synthesis. Moreover, the applied substrates allowed for high synthesis of unsaturated fatty acids (UFA); the level exceeded 90% in the fatty acid pool. Oleic (C18:1) and linoleic acids (C18:2) achieved the highest content. The study showed that Y. lipolytica is able to grow on the seaweed hydrolysate and produces a high content of UFA in the biomass.

Carotenoid content and composition: A special focus on commercially important fish and shellfish

Carotenoids are natural pigments that provide many health benefits to living organisms. Although terrestrial plants are the major dietary source of carotenoids for humans, aquatic animals (especially fish and shellfish) are equally important because they are rich in certain important carotenoids lacking in fruits and vegetables. Although extensive research has focused on exploring the carotenoid content and composition in fish and shellfish, this information is poorly organized. This paper reviews the scientific evidence for the carotenoid content and composition in fish and shellfish. It makes serious attempts to summarize the relevant data published on specific research questions in order to improve the understanding of various evidence to clarify the research status of carotenoids in fish and shellfish and defining topics for future studies. From the analysis of published data, it is obvious that most fish and shellfish are rich in complex carotenoids (e.g. astaxanthin, fucoxanthin, fucoxanthinol, lutein). These carotenoids have stronger antioxidant effect, higher efficiency in removing the singlet oxygen and the peroxyl radicals, and have a variety of health benefits. Carotenoid levels in fish and shellfish depend on genotype, climatic conditions of the production area, storage and cooking methods. However, the information of the bioavailability of fish/shellfish carotenoids to human is very limited, which hinders the actual contributions to health. The findings of this study can be used as a guide to select appropriate fish and shellfish as dietary sources of carotenoids, and provide information about potential fish and shellfish species for aquaculture to produce carotenoids to meet part of the growing demand for natural carotenoids.