Establishing the green algaeChlamydomonas incertaas a platform for recombinant protein production

Chlamydomonas incerta, a genetically close relative of the model green algaChlamydomonas reinhardtii, shows significant potential as a host for recombinant protein expression. Because of the close genetic relationship betweenC. incertaandC. reinhardtii, this species offers an additional reference point for advancing our understanding of photosynthetic organisms, and also provides a potential new candidate for biotechnological applications. This study investigates C. incerta’s capacity to express three recombinant proteins: the fluorescent protein mCherry, the hemicellulose-degrading enzyme xylanase, and the plastic-degrading enzyme PHL7. We have also examined the capacity to target protein expression to various cellular compartments in this alga, including the cytosol, secretory pathway, cytoplasmic membrane, and cell wall. When compared directly withC. reinhardtii,C. incertaexhibited a distinct but notable capacity for recombinant protein production. Cellular transformation with a vector encoding mCherry revealed thatC. incertaproduced approximately 3.5 times higher fluorescence levels and a 3.7-fold increase in immunoblot intensity compared toC. reinhardtii. For xylanase expression and secretion, bothC. incertaandC. reinhardtiishowed similar secretion capacities and enzymatic activities, with comparable xylan degradation rates, highlighting the industrial applicability of xylanase expression in microalgae. Finally,C. incertashowed comparable PHL7 activity levels toC. reinhardtii, as demonstrated by the in vitro degradation of a polyester polyurethane suspension, Impranil® DLN. Finally, we also explored the potential of cellular fusion for the generation of genetic hybrids betweenC. incertaandC. reinhardtiias a means to enhance phenotypic diversity and augment genetic variation. We were able to generate genetic fusion that could exchange both the recombinant protein genes, as well as associated selectable marker genes into recombinant offspring. These findings emphasizeC. incerta’s potential as a robust platform for recombinant protein production, and as a powerful tool for gaining a better understanding of microalgal biology.