Department of Ecology & Research Center for Hydrobiology, Jinan University, Guangzhou, 510632, China.
BGI Genomics, BGI-Shenzhen, Shenzhen, China.
BMC Biol. 2023 Jun 6;21(1):133. doi: 10.1186/s12915-023-01618-x.
With the urgent need to reduce carbon emissions, and the dwindling reserves of easily exploitable fossil fuel, microalgae-based biofuels that can be used for transport systems and CO abatement have attracted great attention worldwide in recent years. One useful characteristic of microalgae is their ability to accumulate high levels of lipid content, in particular under conditions of nitrogen deprivation, with numerous species identified so far. However, a trade-off between levels of lipid accumulation and biomass productivity hinders the commercial applicability of lipids from microalgae. Here, we sequenced the genomes of Vischeria sp. CAUP H4302 and Vischeria stellata SAG 33.83, which can accumulate high content of lipids rich in nutraceutical fatty acids and with excellent biomass yield in nitrogen-limiting culture.
A whole-genome duplication (WGD) event was revealed in V. sp. CAUP H4302, which is a rare event in unicellular microalgae. Comparative genomic analyses showed that a battery of genes encoding pivotal enzymes involved in fatty acids and triacylglycerol biosynthesis, storage polysaccharide hydrolysis, and nitrogen and amino acid-related metabolisms are expanded in the genus Vischeria or only in V. sp. CAUP H4302. The most highlighted is the expansion of cyanate lyase genes in the genus Vischeria, which may enhance their detoxification ability against the toxic cyanate by decomposing cyanate to NH and CO, especially under nitrogen-limiting conditions, resulting in better growth performance and sustained accumulation of biomass under the aforementioned stress conditions.
This study presents a WGD event in microalgae, providing new insights into the genetic and regulatory mechanism underpinning hyper-accumulation of lipids and offering potentially valuable targets for future improvements in oleaginous microalgae by metabolic engineering.
随着减少碳排放的迫切需求，以及可开采化石燃料储量的减少，以微藻为基础的生物燃料，可用于运输系统和 CO 减排，近年来已在全球范围内引起了极大的关注。微藻的一个有用特性是它们能够在氮饥饿条件下积累高水平的脂类，迄今为止已经鉴定出许多种类。然而，脂类积累水平和生物量生产力之间的权衡限制了微藻脂类的商业适用性。在这里，我们对可以在氮限制培养中积累高含量富含营养脂肪酸的脂类和具有优异生物质产量的 Vischeria sp. CAUP H4302 和 Vischeria stellata SAG 33.83 进行了基因组测序。
在 V. sp. CAUP H4302 中揭示了全基因组复制 (WGD) 事件，这在单细胞微藻中是罕见的事件。比较基因组分析表明，一系列编码与脂肪酸和三酰基甘油生物合成、储存多糖水解以及氮和氨基酸相关代谢相关的关键酶的基因在 Vischeria 属中或仅在 V. sp. CAUP H4302 中扩展。最引人注目的是 Vischeria 属中氰酸酶基因的扩展，这可能增强它们对有毒氰酸的解毒能力，通过将氰酸分解为 NH 和 CO 来分解氰酸，特别是在氮限制条件下，从而在上述应激条件下实现更好的生长性能和生物量的持续积累。
本研究在微藻中呈现了全基因组复制事件，为脂质超积累的遗传和调控机制提供了新的见解，并为通过代谢工程提高油脂微藻的产油率提供了有潜在价值的目标。
