Biofuels Engineering

Microalgae are some of the most robust and prolific organisms known to man; their minimal growth requirements and ability to capture energy from sunlight further attest to nature’s evolutionary prowess. For these reasons, microalgae are an attractive platform for the production of various biomolecules. For over 50 years, these unicellular species have been exploited for their natural ability to produce high-value compounds such as antioxidants, polyunsaturated fatty acids, and edible protein for human and aquaculture nutrition (Spolaore et al. 2006). More recently, however, transgenic algae have been developed for recombinant protein expression in the chloroplast (Mayfield et al. 2007). Currently, algae hold great potential for the generation of advanced biomass and biofuel feedstocks (Shenck et al. 2008).

There are many aspects of process engineering associated with microalgal biotechnology, such as photobioreactor design and optimization, harvesting of algal cells, and extraction of desired biomolecules, yet, some of the most significant improvements in efficiency can be made at the sub-cellular level. In order to improve the inherent productivity of these organisms, and even expand their processing capabilities, genetic and metabolic engineering of microalgae must be further developed (Rosenberg et al. 2008). This emerging field has great potential and a number of worthy applications; however, the genetic infrastructure of only a select number of microalgae has been characterized extensively enough to permit such endeavors.

In recent years, our lab has applied the well-established techniques of metabolic engineering in mammalian cell lines to microalgae. In close collaboration with Drs. George Oyler (JHU ChemBE), Stephen Miller (UMBC), Donald Weeks (UNL), and Jim Van Etten (UNL), we have worked toward establishing transformation protocols and expression vectors for a variety of algal species (Fig. 1). Dr. Marc Donohue (JHU ChemBE) has also provided substantial insight regarding novel methods of extracting algal lipids. In the area of biofuels, we are particularly interested in enhanced lipid and isoprenoid biosynthesis and have organized a national consortium of academic researchers dedicated to algal biofuel research, The Algal Bioenergy Alliance.

References:
Spolaore P, Joannis-Cassan C, Duran E, Isambert A: Commercial applications of microalgae. J Biosci Bioeng 2006, 101:87–96

Mayfield SP, Manuell AL, Chen S, Wu J, Tran M, Siefker D, Muto M, Marin-Navarro J: Chlamydomonas reinhardtii chloroplasts as protein factories. Curr Opin Biotechnol 2007, 18:1-8.

Schenk PM, Thomas-Hall SR, Stephens E, Marx UC, Mussgnug JH, Posten C, Kruse O, Hankamer B: Second generation biofuels: high-efficiency microalgae for biodiesel production. Bioenerg Res 2008, 1:20-43.

Rosenberg JN, Oyler GA, Wilkinson L, Betenbaugh MJ: A green light for engineered algae: redirecting metabolism to fuel a biotechnology revolution. Curr Opin Biotechnol 2008, 19:430-36.

 

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