Evaluating novel plant oilseeds enriched in omega-3 long chain polyunsaturated fatty acids to support sustainable development of aquaculture

鱼类作为健康饮食的组成部分，其广泛认可的高度有益作用几乎完全来自于其高含量的长链omega-3多不饱和脂肪酸、EPA和DHA，这些物质对神经的正常发育至关重要，并能预防包括心血管疾病和一些神经系统疾病在内的几种炎症。然而，对野生渔业的过度开发意味着，人类食物篮子中越来越多的鱼类现在是人工养殖的。大西洋鲑鱼，一种所谓的“油性鱼”，可以说是必需omega-3脂肪酸的最佳来源，是英国主要的养殖鱼类。矛盾的是，养殖的肉食性鱼类，包括鲑鱼，传统上以鱼粉和鱼油为基础，而鱼粉和鱼油本身就来自海洋渔业。水产养殖的持续发展要求饲料从这些有限、有限和日益减少的海洋资源转向环境友好和生态可持续的成分，特别是来自陆地农业的植物粕和植物油。然而，植物性饲料的油成分与海洋饲料的油成分有很大的不同，完全缺乏长链omega-3脂肪酸，这不仅对鱼类的健康有重要影响，而且对人类消费者的健康也有重要影响。因此，水产养殖面临的挑战是如何以可持续和环境友好的方式养殖鱼类，同时保持高水平的长链omega-3脂肪酸，使其具有营养质量和作为人类饮食中有益和健康成分的地位。该项目的目的是生产新型植物油，通过含有高水平的长链omega-3脂肪酸，EPA和DHA，专门增强以适应水产养殖业的需求，并可用于替代我们有限的海洋鱼油储备，防止过度开发这种自然资源。这项研究的第一个目标将是开发能够在种子中制造和积累EPA和DHA的油籽植物品种。选择的油籽作物Camelina sativa，也被称为假亚麻或快乐金，是欧洲传统上为取油而种植的油菜籽的亲戚，将使用合成生物学方法进行改造，通过包含藻类基因的植物代谢工程来制造长链omega-3脂肪酸，EPA和DHA，通常只在海洋微藻中产生。第二个具体目标将是研制含有新型长链omega-3亚麻荠籽油的植物性饲料，并在大西洋鲑鱼的喂养试验中对其进行测试，这将确定饲料的效率、营养质量和安全性。第三个目标将是研究鱼类细胞中EPA和DHA的代谢，我们可以非常精确地操纵脂肪酸供应，阐明生物化学途径和分子机制，这些途径和分子机制涉及确定细胞的脂肪酸组成，特别是EPA向DHA的转化。这些细胞研究将通过提供新油中EPA和DHA的水平和比例的数据，为代谢工程实验提供信息，以获得最佳的水产饲料配方性能。由于养殖鲑鱼是英国饮食中长链omega-3的主要来源，每天食用超过120万份鲑鱼，因此该项目可以为英国人口的健康和福祉做出重大贡献。此外，通过提高英国养鱼业的可持续性，该项目将有助于保护大部分农村地区6000多个直接就业和与行业相关的工作岗位。

The widely recognised, highly beneficial effects of fish as components of a healthy diet are almost exclusively derived from their high content of long-chain omega-3 polyunsaturated fatty acids, EPA and DHA, which are known to be essential for proper neural development, and protective against several inflammatory conditions including cardiovascular diseases and some neurological disorders. However, over-exploitation of wild fisheries has meant that an ever-increasing proportion of fish in the human food basket is now farmed. Atlantic salmon, a so-called 'oily fish' and arguably the best source of essential omega-3 fatty acids, are the major farmed fish species in the UK. Paradoxically, diets for farmed carnivorous fish, including salmon, have traditionally been based on fishmeal and fish oil, themselves derived from marine fisheries. Continued development of aquaculture requires feeds to move from these finite, limited and dwindling marine resources to environmentally friendly and ecologically sustainable ingredients, specifically plant meals and vegetable oils, derived from terrestrial agriculture. However, the oil components of plant-based feeds differ substantially from those of marine-based feeds, completely lacking the long-chain omega-3 fatty acids, which has important consequences not only for health of fish, but also the health of human consumers. Therefore, the challenge for aquaculture is how to farm fish in a sustainable and environmentally friendly manner and yet maintain the high levels of long-chain omega-3 fatty acids that confer their nutritional quality and status as beneficial and healthy components of the human diet. The aim of this project is to produce novel vegetable oils specifically enhanced to fit the needs of the aquafeed industry by containing high levels of long-chain omega-3 fatty acids, EPA and DHA, and that can be used to replace our finite reserves of marine fish oil and prevent the over-exploitation of this natural resource. The first goal of the research will be to develop varieties of oilseed plants that can manufacture and accumulate EPA and DHA in their seeds. The oilseed crop of choice, Camelina sativa, also known as false flax or gold-of-pleasure and a relative of rapeseed traditionally grown for oil in Europe, will be modified using a synthetic biology approach that will result in plants metabolically engineered by the inclusion of algal genes to manufacture the long-chain omega-3 fatty acids, EPA and DHA, usually produced only in marine microalgae. The second specific goal will be to formulate plant-based feeds containing the novel, long-chain omega-3 Camelina oils and to test them in feeding trials with Atlantic salmon, which will determine the efficiency, nutritional quality, and safety of the feeds. A third goal will be to study the metabolism of EPA and DHA in fish cells where we can manipulate the fatty acids supplied very precisely and elucidate the biochemical pathways and molecular mechanisms involved in determining the fatty acid composition of cells and, in particular, the conversion of EPA to DHA. These cell studies will inform the metabolic engineering experiments by providing data on the levels and ratios of EPA and DHA required in the novel oils for optimal performance in aquafeed formulations. Since farmed salmon are a major source of long-chain omega-3 in the UK diet, with more than 1.2 million salmon meals eaten per day, this project can make a significant contribution to the health and well-being of the human population in the UK. In addition, by improving the sustainability of the UK fish farming industry, this project will help to protect more than 6000 directly employed and industry-associated jobs in largely rural areas.