Improving Marine Algae for Bioenergy 291
Conclusion
Microalgae use sunlight to produce TAGs and starch, and their biomass productivity greatly exceeds the
best producing crops. In addition, some of the microalgae are also capable of producing hydrogen—a
fuel that liberates a large amount of energy per unit mass. Microalgae biofuel can be produced on nonarable land, using for this purpose saline and wastewater streams. In this way the production of biofuel
by algae will allow arable land to remain available for cultivation of crops, thus avoiding the adverse
impacts on food supplies. For these features, microalgae have been considered a promising platform to
produce of biofuels. However, it is of critical economic importance—for the practical use of microalgae
as source of renewable energy, to achieve a significant improvement in the efficiency of biofuel
production. Nowadays, with genome sequence data and a wide variety of genetic tools and powerful
analytical techniques available, new genetic engineering modifications can be accomplished to exploit
marine algae as efficient sources of biofuels if protocols for chloroplast and nuclear transformations,
and stable expression of genes are developed for species of interest. Such modifications might include
accurate reprogramming and manipulation of metabolic pathways, combined with strategies to overcome
the limitations of CO 2 fixation and light capture, which are crucial to optimize biomass productivity.
Acknowledgements
This study was funded by Fundação para a Ciência e Tecnologia (FCT-Portugal), Units UID/
AGR/04129/2013 and by a grant from the University of Valencia (UV-INV-AE14-269247).
References
Anemaet, I.G., M. Bekker and K.J. Hellingwerf. 2010. Algal photosynthesis as the primary driver for a sustainable development
in energy, feed and food production. Mar. Biotechnol. 12: 619–629.
Antal, T.K., T.E. Krendeleva and E. Tyystjärvi. 2015. Multiple regulatory mechanisms in the chloroplast of green algae:
relation to hydrogen production. Photosynth. Res. 125: 357–381.
Atsumi, S., T. Hanai and J.C. Liao. 2008. Non-fermentative pathways for synthesis of branched-chain higher alcohols as
biofuels. Nature 451: 86–90.
Baebprasert, W., S. Jantaro, W. Khetkorn, P. Lindblad and A. Incharoensakdi. 2011. Increased H 2 production in the
cyanobacterium Synechocystis sp. strain PCC 6803 by redirecting the electron supply via genetic engineering of the
nitrate assimilation pathway. Metab. Eng. 13: 610–616.
Bailey, S., B. Vick and J. Moseley. 2011. Manipulation of an alternative respiratory pathway in photoautotrophs. US Patent
US8709765 B2.
Ball, S.G. and P. Deschamps. 2009. Starch metabolism. The Chlamydomonas Sourcebook. Elsevier Science and Technology,
New York, 2nd Ed. Vol. 2: 1–40.
Ballat, M. 2008. Potential importance of hydrogen as a future solution to environmental and transportation problems. Int. J.
Hydrogen Energy 33: 4013–4029.
Baltz, A., K.V. Dang, A. Beyly, P. Auroy, P. Richaud, L. Cournac and G. Peltier. 2014. Plastidial expression of type II NAD(P)
H dehydrogenase increases the reducing dtate of plastoquinones and hydrogen photoproduction rate by the indirect
pathway in Chlamydomonas reinhardtii. Plant Physiol. 165: 1344–1352.
Banerjee, C., K.K. Dubey and P. Shukla. 2016. Metabolic engineering of microalgal based biofuel production: prospects and
challenges. Front. Microbiol. 7: 432.
Bar-Even, A., E. Noor, N.E. Lewis and R. Milo. 2010. Design and analysis of synthetic carbon fixation pathways. Proc. Natl.
Acad. Sci. USA 107: 8889–8894.
Bar-Even, A., A. Flamholz, E. Noor and R. Milo. 2012. Thermodynamic constraints shape the structure of carbon fixation
pathways. Biochim. Biophys. Acta 1817: 1646–1659.
Batyrova, K. and P.C. Hallenbeck. 2017. Hydrogen production by a Chlamydomonas reinhardtii strain with inducible expression
of Photosystem II. Int J. Mol. Sci. 18: E647.
Bayro-Kaiser, V. and N. Nelson. 2016. Temperature-sensitive PSII: a novel approach for sustained photosynthetic hydrogen
production. Photosynth. Res. 130: 113–121.
Blankenship, R.E., D.M. Tiede, J. Barber, G.W. Brudvig, G. Fleming, M. Ghirardi, M.R. Gunner, W. Junge, D.M. Kramer,
A. Melis, T.A. Moore, C.C. Moser, D.G. Nocera, A.J. Nozik, D.R. Ort, W.W. Parson, R.C. Prince and R.T. Sayre. 2011.
Comparing photosynthetic and photovoltaic efficiencies and recognizing the potential for improvement. Science 332:
805–809.
Blatti, J.L., J. Beld, C.A. Behnke, M. Mendez, S.P. Mayfield and M.D. Burkart. 2012. Manipulating fatty acid biosynthesis in
microalgae for biofuel through protein-protein interactions. PLoS ONE 7(9): e42949. doi:10.1371/journal.pone.0042949.
Conclusion
Microalgae use sunlight to produce TAGs and starch, and their biomass productivity greatly exceeds the
best producing crops. In addition, some of the microalgae are also capable of producing hydrogen—a
fuel that liberates a large amount of energy per unit mass. Microalgae biofuel can be produced on nonarable land, using for this purpose saline and wastewater streams. In this way the production of biofuel
by algae will allow arable land to remain available for cultivation of crops, thus avoiding the adverse
impacts on food supplies. For these features, microalgae have been considered a promising platform to
produce of biofuels. However, it is of critical economic importance—for the practical use of microalgae
as source of renewable energy, to achieve a significant improvement in the efficiency of biofuel
production. Nowadays, with genome sequence data and a wide variety of genetic tools and powerful
analytical techniques available, new genetic engineering modifications can be accomplished to exploit
marine algae as efficient sources of biofuels if protocols for chloroplast and nuclear transformations,
and stable expression of genes are developed for species of interest. Such modifications might include
accurate reprogramming and manipulation of metabolic pathways, combined with strategies to overcome
the limitations of CO 2 fixation and light capture, which are crucial to optimize biomass productivity.
Acknowledgements
This study was funded by Fundação para a Ciência e Tecnologia (FCT-Portugal), Units UID/
AGR/04129/2013 and by a grant from the University of Valencia (UV-INV-AE14-269247).
References
Anemaet, I.G., M. Bekker and K.J. Hellingwerf. 2010. Algal photosynthesis as the primary driver for a sustainable development
in energy, feed and food production. Mar. Biotechnol. 12: 619–629.
Antal, T.K., T.E. Krendeleva and E. Tyystjärvi. 2015. Multiple regulatory mechanisms in the chloroplast of green algae:
relation to hydrogen production. Photosynth. Res. 125: 357–381.
Atsumi, S., T. Hanai and J.C. Liao. 2008. Non-fermentative pathways for synthesis of branched-chain higher alcohols as
biofuels. Nature 451: 86–90.
Baebprasert, W., S. Jantaro, W. Khetkorn, P. Lindblad and A. Incharoensakdi. 2011. Increased H 2 production in the
cyanobacterium Synechocystis sp. strain PCC 6803 by redirecting the electron supply via genetic engineering of the
nitrate assimilation pathway. Metab. Eng. 13: 610–616.
Bailey, S., B. Vick and J. Moseley. 2011. Manipulation of an alternative respiratory pathway in photoautotrophs. US Patent
US8709765 B2.
Ball, S.G. and P. Deschamps. 2009. Starch metabolism. The Chlamydomonas Sourcebook. Elsevier Science and Technology,
New York, 2nd Ed. Vol. 2: 1–40.
Ballat, M. 2008. Potential importance of hydrogen as a future solution to environmental and transportation problems. Int. J.
Hydrogen Energy 33: 4013–4029.
Baltz, A., K.V. Dang, A. Beyly, P. Auroy, P. Richaud, L. Cournac and G. Peltier. 2014. Plastidial expression of type II NAD(P)
H dehydrogenase increases the reducing dtate of plastoquinones and hydrogen photoproduction rate by the indirect
pathway in Chlamydomonas reinhardtii. Plant Physiol. 165: 1344–1352.
Banerjee, C., K.K. Dubey and P. Shukla. 2016. Metabolic engineering of microalgal based biofuel production: prospects and
challenges. Front. Microbiol. 7: 432.
Bar-Even, A., E. Noor, N.E. Lewis and R. Milo. 2010. Design and analysis of synthetic carbon fixation pathways. Proc. Natl.
Acad. Sci. USA 107: 8889–8894.
Bar-Even, A., A. Flamholz, E. Noor and R. Milo. 2012. Thermodynamic constraints shape the structure of carbon fixation
pathways. Biochim. Biophys. Acta 1817: 1646–1659.
Batyrova, K. and P.C. Hallenbeck. 2017. Hydrogen production by a Chlamydomonas reinhardtii strain with inducible expression
of Photosystem II. Int J. Mol. Sci. 18: E647.
Bayro-Kaiser, V. and N. Nelson. 2016. Temperature-sensitive PSII: a novel approach for sustained photosynthetic hydrogen
production. Photosynth. Res. 130: 113–121.
Blankenship, R.E., D.M. Tiede, J. Barber, G.W. Brudvig, G. Fleming, M. Ghirardi, M.R. Gunner, W. Junge, D.M. Kramer,
A. Melis, T.A. Moore, C.C. Moser, D.G. Nocera, A.J. Nozik, D.R. Ort, W.W. Parson, R.C. Prince and R.T. Sayre. 2011.
Comparing photosynthetic and photovoltaic efficiencies and recognizing the potential for improvement. Science 332:
805–809.
Blatti, J.L., J. Beld, C.A. Behnke, M. Mendez, S.P. Mayfield and M.D. Burkart. 2012. Manipulating fatty acid biosynthesis in
microalgae for biofuel through protein-protein interactions. PLoS ONE 7(9): e42949. doi:10.1371/journal.pone.0042949.