Production of milk-derived bioactive peptides as precursor chimeric proteins in chloroplasts of Chlamydomonas reinhardtii

Bioactive peptides are considered high value-added ingredients in functional foods, and the main sources of these are milk, egg, plants, among others. A major limitation in their commercial use is the cost of production. This study deals with the design and production of a chimeric protein in chloroplasts of the microalgae Chlamydomonas reinhardtii to generate bioactive peptides of antihypertensive, opioid, antimicrobial, and hypocholesterolemic activities. A synthetic gene, designated as NCQ, coding for the selected chimeric protein, is transferred to C. reinhardtii using biolistic bombardment. Transplastomic transformants have been identified by PCR and Western blots following selection on a spectinomycin-containing medium. An ELISA quantification assay has revealed that the expressed NCQ protein accumulated at levels ranging between 0.16 and 2.4 % of total soluble protein. These findings demonstrate that chloroplasts of C. reinhardtii could serve as a robust expression platform for production of bioactive peptides.