AUTHOR=Muñoz Camilo F. , Weusthuis Ruud A. , D’Adamo Sarah , Wijffels René H. 

TITLE=Effect of Single and Combined Expression of Lysophosphatidic Acid Acyltransferase, Glycerol-3-Phosphate Acyltransferase, and Diacylglycerol Acyltransferase on Lipid Accumulation and Composition in Neochloris oleoabundans

JOURNAL=Frontiers in Plant Science

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2019.01573

DOI=10.3389/fpls.2019.01573

ISSN=1664-462X

ABSTRACT=<p>Microalgal lipids are promising feedstocks for food and biofuels. Since lipid production by microalgae is not yet economically feasible, genetic engineering is becoming a promising strategy to achieve higher lipid accumulation and productivities. Enzymes involved in the Kennedy pathway such as glycerol-3-phosphate acyltransferase (GPAT), lysophosphatidic acid acyltransferase (LPAT), and diacylglycerol acyltransferase (DGAT) catalyze key steps in the formation of triacylglycerol, which is the main constituent of lipids in <italic>N. oleoabundans</italic>. The overexpression of these enzymes in the targeted strain has a great potential to further increase their triacylglycerol content. We overexpressed single and multiple encoding genes for <italic>LPAT</italic>, <italic>GPAT</italic>, and <italic>DGAT</italic> from <italic>Acutodesmus obliquus</italic> in <italic>N. oleoabundans</italic>. Strains overexpressing single genes produced up to 52% and 45% g · gDW<sup>-1</sup>, which corresponds to 1.3- and 1.4-fold increase in total fatty acids and triacylglycerols, respectively. The orchestrated expression of the three genes resulted in 49% and 39% g · gDW<sup>-1</sup>, which is 1.2-folds increase in total fatty acids and triacylglycerols. Single expression of <italic>LPAT</italic>, <italic>GPAT,</italic> and <italic>DGAT</italic> genes resulted in higher lipid productivities during starvation without a significant effect on growth and photosynthetic activity during replete conditions. On the other hand, the simultaneous expression of <italic>LPAT</italic>, <italic>GPAT,</italic> and <italic>DGAT</italic> genes resulted in 52% lower growth rate, 14% lower photosynthetic activity and 4-folds increase in cell diameter. Moreover, the multigene expressing line showed a decrease in carbohydrates and protein content and an increase in pigments during nitrogen starved condition. The single and multiple expression of heterologous genes <italic>LPAT</italic>, <italic>GPAT,</italic> and <italic>DGAT</italic> showed to significantly enhanced the lipid accumulation in <italic>N. oleoabundans</italic>. Single gene expression resulted in higher lipid production and productivities without having a significant impact in the physiological status of the strains. This approach shows the potential for the generation of microalgal strains with higher economical potential for the production of lipids.</p>