Engineering the novel extremophile alga Chlamydomonas pacifica for high lipid and high starch production as a path to developing commercially relevant strains

Abstract

Microalgae offer a compelling platform for the production of commodity products, due to their superior photosynthetic efficiency, adaptability to non-arable lands and non-potable water, and their capacity to produce a versatile array of bioproducts, including biofuels and biomaterials. However, the scalability of microalgae as a bioresource has been hindered by challenges such as costly biomass production related to vulnerability to pond crashes during large-scale cultivation. This study presents a pipeline for the genetic engineering and pilot-scale production of biodiesel and thermoplastic polyurethane precursors in the extremophile species Chlamydomonas pacifica. This extremophile microalga exhibits exceptional resilience to high pH, high salinity, and elevated temperatures. Initially, we evolved this strain to also have a high tolerance to high light intensity through mutagenesis, breeding, and selection. Subsequently, we genetically engineered C. pacifica to produce high levels of lipids and starch without compromising growth. We demonstrated the scalability of these engineered strains by cultivating them in pilot-scale raceway ponds and converting the resulting biomass into biodiesel and thermoplastic polyurethanes. This study showcases the complete cycle of transforming a newly discovered species into a commercially relevant commodity production strain. This research underscores the potential of extremophile algae, including C. pacifica, as a key species for the burgeoning sustainable bioeconomy, offering a viable path forward in mitigating environmental challenges and supporting global bioproduct demands. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=90 SRC="FIGDIR/small/604193v1_ufig1.gif" ALT="Figure 1"> View larger version (25K): org.highwire.dtl.DTLVardef@84948eorg.highwire.dtl.DTLVardef@352616org.highwire.dtl.DTLVardef@1577082org.highwire.dtl.DTLVardef@19b8644_HPS_FORMAT_FIGEXP M_FIG C_FIG