(582ax) Development of Novel Feed Additives Through the Production of Recombinant Proteins in Microalgal Chloroplasts

Microalgae offer many advantages as systems for recombinant protein production, as they combine the high growth rate and ease of cultivation of microorganisms with the ability to perform post-transcriptional and post-translational modifications of plant systems. Given that many microalgal species are deemed safe for consumption, and are in fact of considerable nutritional value, they present an interesting potential platform for the production of orally delivered therapeutics and vaccines, or as animal feed additives, while avoiding extensive purification costs associated with conventional recombinant microorganism fermentation-based production systems.

     Despite advances over the last decade, however, high-level (i.e. economically viable) expression of recombinant products in microalgae remains anecdotal, and a comprehensive understanding of the factors and systems involved in product yield regulation remains elusive. Several proteins of industrial and therapeutic interest have successfully been expressed at sufficient levels in microalgal chloroplasts, but expression of other genes in otherwise identical expression cassettes is not met with the same success. Despite these drawbacks, microalgae are increasingly regarded as versatile and advantageous recombinant protein expression platforms.

     Our research focuses on the development and cultivation of novel recombinant microalgal strains which express and store enzymes that improve nutrient utilization and degradation of non-digestible matter by animals. When fed to crop animals, such microalgal additives not only provide the nutritional benefits of the enzymes, already recognized and exploited in animal feeds through purified additives, but also provide the value-added nutrition of microalgal biomass, while conferring environmental benefits through decreased nutrient waste. The expression of different gene constructs, under the control of different 5’UTR/promoter sequences, and designed using different codon optimization algorithms, is being investigated, in conjunction with the enzymatic activities of cell culture lysates. The production of products destined for other applications, notably enzymes of therapeutic or medical interest, is also being pursued.