Using the tools of genetic engineering, recombinant proteins can be produced using a variety of expression systems and hosts, including microbial, mammalian, insect, plant or algal cells grown in bioreactors as well as transgenic animals and plants. Our laboratory is developing novel expression systems (i.e. the genetic instructions that direct the host cell to produce the non-native protein) and bioprocess engineering technologies to produce recombinant proteins, including human therapeutic proteins, enzymes for cellulose degradation, and biopolymers for materials applications, using whole plants, harvested plant tissues or plant cells grown in-vitro in bioreactors.