Heterologous expression of a yeast lipid transporter promotes accumulation of storage compounds in chlamydomonas

Authors: Msanne, Joseph; Ashby, Richard - Rick; Olanya, Modesto

Submitted to: Biocatalysis and Agricultural Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/5/2023
Publication Date: 8/6/2023
Citation: Msanne, J.N., Ashby, R.D., Olanya, O.M. 2023. Heterologous expression of a yeast lipid transporter promotes accumulation of storage compounds in chlamydomonas. Biocatalysis and Agricultural Biotechnology. https://doi.org/10.1016/j.bcab.2023.102809.
DOI: https://doi.org/10.1016/j.bcab.2023.102809

Interpretive Summary: Sustainable biomass produced from green microalgae is a valuable alternative for the commercial production of both biofuels and other biomaterials, which are currently produced from crops used as food or feed. Environmentally friendly products extracted from microalgal feedstocks also have the potential to replace petroleum-derived equivalents based on comparable functional properties. In this study, the genetic engineering of the green microalga Chlamydomonas reinhardtii by introduction of a yeast lipid transport protein resulted in improved growth as well as carbon storage compound formation and accumulation. These high-value chemicals can serve as precursors for both biofuel and biomaterial production. Engineered production strains that are capable of sustaining higher biomass and overproduce target chemicals may be essential for the industrial production and long-term economic viability of algal-based bioproducts.

Technical Abstract: Microalgae offer renewable and sustainable sources for the bioindustrial production of next-generation biofuels and biomaterials. In this work, we heterologously expressed a lipid transporter gene (MMF1) from the major facilitator superfamily in the model green alga Chlamydomonas reinhardtii, under the influence of a strong light and temperature-inducible promoter. The full-length cDNA sequence of MMF1 from Moesziomyces antarcticus T-34 (MaMMF1) encodes for a 542 amino acid polypeptide with thirteen transmembrane regions. M. antarcticus is a fungus that can produce and secrete large amounts of glycolipid biosurfactants known as mannosylerythritol lipids (MELs) under nitrogen starvation conditions. Heterologous expression of MaMMF1 in C. reinhardtii resulted in a slight increase in biomass, with mutants exhibiting on average about 1.8-fold larger cell sizes. Total lipid content almost doubled in cells expressing MaMMF1 relative to the control strain when cultures were grown for two days under nitrogen starvation. Moreover, starch content was on average over 2-fold higher in the mutants. Our results showed that algal strains engineered with the MaMMF1 MEL transporter were capable of possibly redirecting the carbon flux, which resulted in improved growth and accumulation of high-value storage compounds.