Transgenic microalgae as green cell-factories

There is increasing interest in the use of microalgae for biotechnological applications and as plant model systems. Although biotechnological processes based on transgenic microalgae are still in their infancy, researchers and companies are considering the potential of microalgae as green cell-factories to produce value-added metabolites and heterologous proteins for pharmaceutical applications. New molecular biology tools are needed to standardize genetic modifications of microalgae. Here, we outline methods and strategies for efficient nuclear transformation of microalgae, and discuss the main difficulties associated with stable expression of transgenes. Most progress in the field has been made with Chlamydomonas reinhardtii, but other species have now been successfully transformed, and many others will be transformed in the near future.