ERA-IB5-The exploitation of Xanthophyllomyces dendrorhous as a sustainable platform for the PROduction of high-value CARotenoids

类胡萝卜素色素在商业上被用作化妆品和保健品中的生物活性物质，各种饲料中的添加剂，香料、香料和着色剂，以及重要的工业原料和精细化学品。它们的工业相关性也意味着它们是高价值的化合物，全球市场每年的规模在10亿美元左右。到目前为止，化学合成一直是首选的生产方法。这种生产仍然昂贵，会产生反应污染物、非天然立体异构体，而且通常与使用不可再生能源的化学精炼厂有关。类胡萝卜素的植物来源很多。然而，它们通常是次生代谢物，通常是在植物生命周期的特定发展阶段由不适应现代农业实践的未充分利用、生长缓慢的稀有物种在特定细胞类型、器官或组织中产生的。植物细胞培养极易受到污染，与微生物来源相比，细胞的大小限制了生物量的产生。藻类资源需要强光，在下游加工过程中需要大量的能量投入，分子资源不足以提供有竞争力的产量。现代分子途径工程和菌种改良方法的出现，以及发酵技术和下游加工的同步进步，意味着微生物生产是一种具有竞争力的可持续替代植物和化学生产的方法。这种方法也不会与土地资源争夺粮食生产，也不会对我们日益减少的化石燃料来源产生影响。因此，微生物平台的开发为创造具有更好的经济和环境资质的有价值的化学品的可再生生物资源提供了一个合乎逻辑的解决方案。在拟议的项目中，树状红酵母(原法夫酵母)将被开发为一种基于微生物的高价值胡萝卜素即玉米黄质和植烯的可再生来源。在需求的推动下，这两种类胡萝卜素的市场正在迅速增长。据估计，到2018年，全球玉米黄质市场将达到3.34亿美元(BCC Research Report FOD025C)。对玉米黄质的兴趣与其作为治疗和预防老年性黄斑变性(AMD)的措施有关。在西方社会，慢性眼病AMD占所有失明病例的54%。植烯是一种无色胡萝卜素，在迅速发展的化妆品工业中用作生物活性成分(Von Oppen-Bezalel等人)。2007年，S《金融时报》--期刊07)。它的有益活动包括防止紫外线和氧化损伤，这会导致过早衰老和其他现象。作为类胡萝卜素的生产系统，黄叶霉菌具有天然高产香叶基香叶基焦磷酸(GGPP)衍生萜类化合物的优势。例如，大多数细菌和酵母(如酵母菌)产生高水平的法尼基二磷酸酯(FPP)，它们不能合成更长链的GGPP衍生的萜类化合物，如类胡萝卜素。因此，合成和积累这类化合物的内在新陈代谢和调节机制在这种有机体中进化了。技术的进步意味着黄叶霉菌现在已经有了一个测序和注释的基因组，建立了代谢组平台，并且可以很容易地用一套能够以稳定的方式将多个基因整合到基因组中的组合载体进行转化，并可以利用农工业废弃物作为碳源。可获得积累不同异戊二烯前体的突变体，并建立了从实验室到工业规模的发酵程序。因此，该项目将利用及时的发展创建一个基于微生物的平台，能够提供高价值胡萝卜素的可再生来源。

Carotenoids pigments are used commercially as bioactives in cosmetics and health supplements, additives in a variety of feedstuffs, as fragrances, flavours and colorants as well as important industrial raw materials and fine chemicals. Their industrial relevance also means they are compounds of high-value with global markets in the range of $ 1 billion per annum. To date chemical synthesis has been the production method of choice. Such production remains expensive, creates reaction contaminants, non-native stereo isomers and is typically associated with chemical refineries using non-renewable energy sources. Numerous plant sources exist for carotenoids. However they are typically secondary metabolites often being produced in specialised cell types, organs or tissues at a specific developmental stage of the plant's life cycle by underutilised, slow growing and rare species that are not amenable to modern agricultural practices. Plant cell culture is highly prone to contamination and the size of the cells restricts biomass production in comparison to microbial sources. Algal sources require intense light, significant energy input during down-stream processing and the molecular resources are not adequately advanced to deliver competitive yields.The onset of modern molecular approaches to pathway engineering and strain improvement, with the concurrent advances in fermentation technologies and down-stream processing means microbial production is a competitive sustainable alternative to plant and chemical based production. This approach also does not compete with land resources for food production or impact on our dwindling sources of fossil fuel. Therefore the development of microbial platforms provides a logical solution to the creation of renewable biosources of valuable chemicals with improved economic and environmental credentials. In the proposed project the red yeast Xanthophyllomyces dendrorhous (formerly Phaffia rhodozyma) will be developed as a microbial based renewable source of high-value carotenoids namely zeaxanthin and phytoene. Driven by demand the markets for these two carotenoids are rapidly growing. It is estimated that the global market for zeaxanthin will reach $334 million by 2018 (BCC Research report FOD025C). This interest in zeaxanthin is associated with its use as a treatment and preventative measure against Age Related Macular Degeneration (AMD). The chronic eye disorder AMD accounts for 54% of all cases of blindness in Western societies. Phytoene is a colourless carotene used as a bioactive ingredient in the rapidly expanding cosmetic industry (Von Oppen-Bezalel et al. 2007, SöFW-Journal 07). Its beneficial activities include protection against UV and oxidative damage, which lead to pre-mature ageing and other phenomena. As a production system for carotenoids Xanthophyllomyces has the advantage of being a naturally high producer of geranylgeranyl pyrophosphate (GGPP) derived terpenoids. For example, most bacteria and yeasts (such Saccharomyces) produce high levels of farnesyl diphospate (FPP), they do not synthesis longer chain GGPP derived terpenoids such as carotenoids. Thus intrinsic metabolism and regulatory mechanisms to synthesise and accumulate such compounds have evolved in this organism. Technological advances mean that Xanthophyllomyces now has a sequenced and annotated genome, established metabolomic platforms and is readily amenable to transformation with a suite of combinatory vectors capable of integrating multiple genes into the genome in a stable manner and can utilise agro-industry waste as carbon sources. Mutants accumulating different isoprenoid precursors are available and fermentation procedures from the laboratory to industrial scale established. Thus the project will exploit timely developments to create a microbial based platform capable of delivering renewable sources of high-value carotenoids.