MOLECULAR STRATEGIES TO INCREASE LIPID PRODUCTION IN THE DIATOM Phaeodactylum tricornutum

BERDUN, FEDERICO; VALIÑAS, MATIAS ; MARCHETTI, MARIA FERNANDA ; PAGNUSSAT, GABRIELA ; ZABALETA, EDUARDO

Cordoba, Los Cocos

Congreso; XVII Congreso Argentino de Microbiología General; 2022

The increase of the world population, the progressive industrialization and the continued growth transportation are among the main factors contributing to growing energy demand. The 80% of current energy demand comes from non-renewable fossil sources, and the concomitant gas emission contributes to the global warming. Thus, research on other more sustainable energy sources, such as microalgae, represents an interesting alternative taking into account its high growth rate, its ability to growth in marginal and no cultivable lands, the possibility to be biochemically and genetically modulated and the production of molecules of industrial interest (biorefineries).The marine diatom Phaeodactylum tricornutum accumulates high lipid content under adverse conditions, however compromising its growth and hindering the commercial value. With the aim to increase the lipid accumulation in this diatom, we investigate the regulation of the cytosolic Acetyl-CoA carboxylase (ACCase), which catalyzes the first committed step of the fatty acid biosynthetic pathway. In this work, we show that ACCase overexpression in the cytosol leads to an increased neutral lipid production. The complete 6879 bp gene (ACCase) was cloned into a vector plasmid under the pFcpB promoter and mobilized to the diatom cells by conjugation technique. The ACCase expression was tested by qPCR and western blot analyses showing an increase compared with the endogenous expression. To understand how metabolic flux changes in the ACCase overexpressed strain, the expression of key enzymes involved in tri-acyl-glyceride synthesis was also monitored. In two different approaches used, a significant increase in lipid concentration has been observed. The increased expression of thioesterase, fatty acid desaturases, and diacylglycerol transferase in response to ACCase overexpression suggests that malonyl coA flows into the triacylglyceride synthesis pathway.