BACKGROUND Pythium irregulare is an oleaginous Oomycete able to accumulate large amounts of lipids, including Eicosapentaenoic acid (EPA). EPA is an important and expensive dietary supplement with a promising and very competitive market, which is dependent on fish-oil extraction. This has prompted several research groups to study biotechnological routes to obtain specific fatty acids rather than a mixture of various lipids. Moreover, microorganisms can use low cost carbon sources for lipid production, thus reducing production costs. Previous studies have highlighted the production of EPA by P. irregulare, exploiting diverse low cost carbon sources that are produced in large amounts, such as vinasse, glycerol, and food wastewater. However, there is still a lack of knowledge about its biosynthetic pathways, because no functional annotation of any Pythium sp. exists yet. The goal of this work was to identify key genes and pathways related to EPA biosynthesis, in P. irregulare CBS 494.86, by sequencing and performing an unprecedented annotation of its genome, considering the possibility of using wastewater as a carbon source. RESULTS Genome sequencing provided 17,727 candidate genes, with 3809 of them associated with enzyme code and 945 with membrane transporter proteins. The functional annotation was compared with curated information of oleaginous organisms, understanding amino acids and fatty acids production, and consumption of carbon and nitrogen sources, present in the wastewater. The main features include the presence of genes related to the consumption of several sugars and candidate genes of unsaturated fatty acids production. CONCLUSIONS The whole metabolic genome presented, which is an unprecedented reconstruction of P. irregulare CBS 494.86, shows its potential to produce value-added products, in special EPA, for food and pharmaceutical industries, moreover it infers metabolic capabilities of the microorganism by incorporating information obtained from literature and genomic data, supplying information of great importance to future work.

中文翻译：

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全基因组测序和不规则腐霉菌CBS 494.86的代谢注释：了解二十碳五烯酸的生产。

背景技术不规则腐霉是一种油质卵菌，能够积聚大量脂质，包括二十碳五烯酸（EPA）。EPA是一种重要且昂贵的膳食补充剂，其市场前景广阔且竞争激烈，这取决于鱼油的提取。这促使一些研究小组研究生物技术途径以获得特定的脂肪酸，而不是各种脂质的混合物。此外，微生物可以使用低成本的碳源生产脂质，从而降低生产成本。先前的研究强调了不规则假单胞菌的EPA生产，它利用了大量生产的低成本低成本碳源，例如酒糟，甘油和食品废水。但是，仍然缺乏有关其生物合成途径的知识，因为没有任何Pythium sp的功能注释。存在。这项工作的目标是通过对序列进行测序并对其基因组进行前所未有的注释，从而考虑到利用废水作为碳源的可能性，从而确定了不规则假单胞菌CBS 494.86中与EPA生物合成相关的关键基因和途径。结果基因组测序提供了17727个候选基因，其中3809个与酶密码相关，而945个与膜转运蛋白相关。将功能注释与精选的含油生物信息，了解氨基酸和脂肪酸的生产以及废水中存在的碳和氮源的消耗进行了比较。主要特征包括存在与消耗几种糖有关的基因和不饱和脂肪酸生产的候选基因。