Effect of recombinant protein production and release on microalgal fitness and the impact of environmental conditions for localized therapeutic delivery

Abstract

Backgroud: Genetically engineered photosynthetic microorganisms have been proposed as a therapeutic approach for the localized delivery of oxygen and recombinant proteins to tissues in various pathological conditions. However, the effect of recombinant protein production and secretion on microalgal fitness, as well as the impact of key environmental conditions on their potential therapeutic performance, has not yet been described. Therefore, in this study, the microalga Chlamydomonas reinhardtii was genetically engineered to produce and release the reporter protein mVenus and was then challenged by exposure to different media, temperatures, and substrates. Results: The genetically modified microalgae were able to produce and release the mVenus protein under standard culture conditions without affecting overall fitness, including cell size and shape, growth potential, and oxygen metabolism, compared to the wild-type strain. Under mammalian cell culture conditions, the strains continued to produce and secrete mVenus protein for up to four days at 22 °C, 30 °C, and 37 °C. Additionally, photosynthetic biomaterials containing the engineered microalgae showed continuous recombinant protein release at 30 °C and 37 °C for up to four days. Conclusion: The microalga Chlamydomonas reinhardtii can be genetically engineered to produce and release recombinant proteins without detrimental effects on its fitness, showing therapeutic potential under mammalian culture conditions and within biomaterials designed to promote tissue regeneration. Overall, these findings support the use of genetically engineered photosynthetic microalgae for the localized and controlled release of oxygen and recombinant proteins for several therapeutic applications.