Szczepańczyk Mateusz, Rzechonek Dorota A, Dobrowolski Adam, Mirończuk Aleksandra M
Wrocław University of Environmental and Life Sciences, Institute of Environmental Biology, Laboratory for Biosustainability, 5b Kozuchowska St, Wroclaw, 51-631, Poland.
Department of Life Sciences (LIFE), Chalmers University of Technology, Kemivägen 10, Göteborg, SE-412 96, Sweden.
Microb Cell Fact. 2025 Mar 26;24(1):72. doi: 10.1186/s12934-025-02699-9.
Yarrowia lipolytica possesses the capability to utilize many unconventional carbon sources, such as crude glycerol, alkanes and fatty acids. Despite producing polyols, such as erythritol, arabitol and mannitol, the re-utilization of mannitol is not as efficient as erythritol utilization. Genes involved in mannitol uptake and metabolism in Y. lipolytica remain undescribed. However, deletion of the EYD1 gene (YALI0F01650g), believed to encode erythritol dehydrogenase, has been found to result in a high rate of growth on media containing mannitol as the sole carbon source. Therefore this unique feature was used for further fermentation studies on media containing macroalgal mannitol extracts, obtained from the brown alga Fucus vesiculosus, to produce value-added products.
The obtained strain AJD Δeyd1Dga1 was able to uptake pure and algal mannitol efficiently and produce high amounts of lipids, thanks to overexpression of the DGA1 gene (YALI0E32769g), encoding diacylglycerol (DAG) acyltransferase. The lipid content reached almost 32% of the overall dry biomass as compared to the wild type strain, where this value was more than 4 times lower. Additionally, the biomass at the end of the experiment was the highest among all of the tested strains, reaching 12.67 g/L, more than 50% higher than the control strain.
The results of this study shed new light on the potential for the yeast Y. lipolytica to utilize macroalgae biomass as a carbon source for production of value-added products, including biomass and lipids. Moreover, the increased mannitol utilization capabilities can provide new insight into mannitol metabolism, including its uptake, which is especially crucial, as the metabolic pathways for all polyols produced by this organism seem to be closely intertwined.
解脂耶氏酵母具有利用多种非常规碳源的能力，如粗甘油、烷烃和脂肪酸。尽管该酵母能产生多元醇，如赤藓糖醇、阿拉伯糖醇和甘露醇，但甘露醇的再利用效率不如赤藓糖醇。解脂耶氏酵母中参与甘露醇摄取和代谢的基因仍未被描述。然而，据信编码赤藓糖醇脱氢酶的EYD1基因（YALI0F01650g）缺失后，发现该酵母在以甘露醇作为唯一碳源的培养基上生长速率很高。因此，利用这一独特特性，对从褐藻墨角藻中提取的大型海藻甘露醇提取物作为培养基进行进一步发酵研究，以生产高附加值产品。
由于编码二酰基甘油（DAG）酰基转移酶的DGA1基因（YALI0E32769g）过表达，所得菌株AJD Δeyd1Dga1能够高效摄取纯甘露醇和海藻甘露醇，并产生大量脂质。与野生型菌株相比，脂质含量达到总干生物量的近32%，而野生型菌株的这一数值要低4倍多。此外，在所有测试菌株中，该菌株在实验结束时的生物量最高，达到12.67 g/L，比对照菌株高出50%以上。
本研究结果为解脂耶氏酵母利用大型海藻生物质作为碳源生产包括生物质和脂质在内的高附加值产品的潜力提供了新的见解。此外，甘露醇利用能力的提高可为甘露醇代谢，包括其摄取提供新的认识，这一点尤为关键，因为该生物体产生的所有多元醇的代谢途径似乎紧密相连。
