Overcoming biological constraints to enable the exploitation of microalgae for biofuels.

Microalgae have significant potential to form the basis of the next biofuel revolution. They have high growth and solar energy conversion rates. Furthermore, their osmotolerance, metabolic diversity and capacity to produce large amounts of lipids have attracted considerable interest. Although there are a handful of commercially successful examples of the photoautotrophic mass-culture of algae, these have focused on the production of higher value products (pigments, health-foods etc.). The technical and commercial challenges to develop an economically viable process for biofuels are considerable and it will require much further R&D. In this paper the biological constraints, with a particular focus on strain selection are discussed.

[1]  S. Heaney,et al.  OBSERVATIONS ON ZOOSPORIC FUNGI OF CERATIUM SPP. IN LAKES OF THE ENGLISH LAKE DISTRICT; IMPORTANCE FOR PHYTOPLANKTON POPULATION DYNAMICS , 1984 .

[2]  Nicholas H. Putnam,et al.  The tiny eukaryote Ostreococcus provides genomic insights into the paradox of plankton speciation , 2007, Proceedings of the National Academy of Sciences.

[3]  Navid Reza Moheimani,et al.  The long-term culture of the coccolithophore Pleurochrysis carterae (Haptophyta) in outdoor raceway ponds , 2006, Journal of Applied Phycology.

[4]  C. Gobler,et al.  Niche of harmful alga Aureococcus anophagefferens revealed through ecogenomics , 2011, Proceedings of the National Academy of Sciences.

[5]  M. Borowitzka,et al.  The protozoa of a Western Australian hypersaline lagoon , 1983, Hydrobiologia.

[6]  M. Droop Auxotrophy and organic compounds in the nutrition of marine phytoplankton. , 1957, Journal of general microbiology.

[7]  A. Belay Mass culture of Spirulina outdoors--the earthrise farms experience , 1997 .

[8]  P. Falkowski,et al.  Chloroplast redox regulation of nuclear gene transcription during photoacclimation , 1997, Photosynthesis Research.

[9]  E. Grotewold Transcription factors for predictive plant metabolic engineering: are we there yet? , 2008, Current opinion in biotechnology.

[10]  Jean-Michel Claverie,et al.  The Chlorella variabilis NC64A Genome Reveals Adaptation to Photosymbiosis, Coevolution with Viruses, and Cryptic Sex[C][W] , 2010, Plant Cell.

[11]  James R. Bolton,et al.  THE MAXIMUM EFFICIENCY OF PHOTOSYNTHESIS * , 1991 .

[12]  K. Keating,et al.  Allelopathic Influence on Blue-Green Bloom Sequence in a Eutrophic Lake , 1977, Science.

[13]  Leszek Rychlewski,et al.  The Phaeodactylum genome reveals the evolutionary history of diatom genomes , 2008, Nature.

[14]  E. Becker Microalgae: Biotechnology and Microbiology , 1994 .

[15]  C. Lan,et al.  Enhancement of lipid production using biochemical, genetic and transcription factor engineering approaches. , 2009, Journal of biotechnology.

[16]  Emilio Fernández,et al.  Transgenic microalgae as green cell-factories. , 2004, Trends in biotechnology.

[17]  E. Jarvis,et al.  GENETIC TRANSFORMATION OF THE DIATOMS CYCLOTELLA CRYPTICA AND NAVICULA SAPROPHILA , 1995 .

[18]  Kyle Bibby,et al.  Transcriptome sequencing and annotation of the microalgae Dunaliella tertiolecta: Pathway description and gene discovery for production of next-generation biofuels , 2011, BMC Genomics.

[19]  Shin-Han Shiu,et al.  Changes in Transcript Abundance in Chlamydomonas reinhardtii following Nitrogen Deprivation Predict Diversion of Metabolism1[W][OA] , 2010, Plant Physiology.

[20]  J. Jurka,et al.  Genomic Analysis of Organismal Complexity in the Multicellular Green Alga Volvox carteri , 2010, Science.

[21]  Abdul Rahman Mohamed,et al.  Utilization of oil palm as a source of renewable energy in Malaysia , 2008 .

[22]  Corinne Da Silva,et al.  The Ectocarpus genome and the independent evolution of multicellularity in brown algae , 2010, Nature.

[23]  T. Kuroiwa,et al.  A 100%-complete sequence reveals unusually simple genomic features in the hot-spring red alga Cyanidioschyzon merolae , 2007, BMC Biology.

[24]  Lutz Wobbe,et al.  Improvement of light to biomass conversion by de-regulation of light-harvesting protein translation in Chlamydomonas reinhardtii. , 2009, Journal of biotechnology.

[25]  Philip Owende,et al.  Biofuels from microalgae—A review of technologies for production, processing, and extractions of biofuels and co-products , 2010 .

[26]  B. Ibelings,et al.  Parasitic chytrids: their effects on phytoplankton communities and food-web dynamics , 2007, Hydrobiologia.

[27]  G. Knothe Improving biodiesel fuel properties by modifying fatty ester composition , 2009 .

[28]  Michael A. Borowitzka,et al.  Culturing microalgae in outdoor ponds , 2005 .

[29]  H. Iwamoto,et al.  Industrial Production of Microalgal Cell‐Mass and Secondary Products ‐ Major Industrial Species: Chlorella , 2007 .

[30]  L. Stal,et al.  Biochemical partitioning of photosynthetically fixed carbon by benthic diatoms during short-term incubations at different irradiances , 2002 .

[31]  G. Lambrinidis,et al.  Effect of temperature on growth, chemical composition and fatty acid composition of tropical Australian microalgae grown in batch cultures , 2002 .

[32]  D. A. Wardle,et al.  Global sale of green air travel supported using biodiesel 1 1 A web page devoted to this topic will , 2003 .

[33]  M. Fasham,et al.  Photosynthetic response of phytoplankton to light: a physiological model , 1983, Proceedings of the Royal Society of London. Series B. Biological Sciences.

[34]  B. De Baets,et al.  Genome analysis of the smallest free-living eukaryote Ostreococcus tauri unveils many unique features. , 2006, Proceedings of the National Academy of Sciences of the United States of America.

[35]  J. Cañavate,et al.  Assessing chemical compounds for controlling predator ciliates in outdoor mass cultures of the green algae Dunaliella salina , 2001 .

[36]  Nicholas H. Putnam,et al.  The Genome of the Diatom Thalassiosira Pseudonana: Ecology, Evolution, and Metabolism , 2004, Science.

[37]  M. Ramos,et al.  Influence of fatty acid composition of raw materials on biodiesel properties. , 2009, Bioresource technology.

[38]  Sara L. Zimmer,et al.  The Chlamydomonas Genome Reveals the Evolution of Key Animal and Plant Functions , 2007, Science.

[39]  Lewis M. Brown,et al.  Genetic Engineering Approaches for Enhanced Production of Biodiesel Fuel from Microalgae , 1994 .

[40]  Y. Chisti,et al.  A mechanistic model of photosynthesis in microalgae. , 2003, Biotechnology and bioengineering.

[41]  Chris J. Hulatt,et al.  Dissolved organic matter (DOM) in microalgal photobioreactors: a potential loss in solar energy conversion? , 2010, Bioresource technology.

[42]  A. Vonshak,et al.  Lipid and fatty acid composition of the green oleaginous alga Parietochloris incisa, the richest plant source of arachidonic acid. , 2002, Phytochemistry.

[43]  Steven Henikoff,et al.  Targeted screening for induced mutations , 2000, Nature Biotechnology.

[44]  J. Dyer,et al.  Oil accumulation in leaves directed by modification of fatty acid breakdown and lipid synthesis pathways. , 2009, Plant biotechnology journal.

[45]  R. Andersen,et al.  Algal culturing techniques , 2005 .

[46]  J. Lawrence Furtive foes: algal viruses as potential invaders , 2008 .

[47]  G. Charles Dismukes,et al.  Increased Lipid Accumulation in the Chlamydomonas reinhardtiista7-10 Starchless Isoamylase Mutant and Increased Carbohydrate Synthesis in Complemented Strains , 2010, Eukaryotic Cell.

[48]  Gokare A. Ravishankar,et al.  Studies on Haematococcus pluvialis for improved production of astaxanthin by mutagenesis , 2001 .

[49]  Q. Hu,et al.  Microalgal triacylglycerols as feedstocks for biofuel production: perspectives and advances. , 2008, The Plant journal : for cell and molecular biology.

[50]  David Lee,et al.  Evaluating genetic containment strategies for transgenic plants. , 2006, Trends in biotechnology.

[51]  D. Weeks,et al.  Molecular analysis of the acetolactate synthase gene of Chlamydomonas reinhardtii and development of a genetically engineered gene as a dominant selectable marker for genetic transformation. , 2002, The Plant journal : for cell and molecular biology.

[52]  R. Sandaa,et al.  Response of marine viral populations to a nutrient induced phytoplankton bloom at different pCO 2 levels , 2008 .

[53]  J. Benemann,et al.  Look Back at the U.S. Department of Energy's Aquatic Species Program: Biodiesel from Algae; Close-Out Report , 1998 .

[54]  A. Richmond,et al.  The use of rotifers for the maintenance of monoalgal mass cultures of Spirulina , 1987, Biotechnology and bioengineering.

[55]  Teresa M. Mata,et al.  Microalgae for biodiesel production and other applications: A review , 2010 .

[56]  R. Lovitt,et al.  Selection for fitness at the individual or population levels: modelling effects of genetic modifications in microalgae on productivity and environmental safety. , 2010, Journal of theoretical biology.

[57]  A. Richmond Handbook of microalgal culture: biotechnology and applied phycology. , 2004 .

[58]  J. Day,et al.  Cryopreservation Methods for Maintaining Cultures. , 2005 .

[59]  A. Ramazanov,et al.  Isolation and characterization of a starchless mutant of Chlorella pyrenoidosa STL‐PI with a high growth rate, and high protein and polyunsaturated fatty acid content , 2006 .

[60]  H A Spoehr,et al.  THE CHEMICAL COMPOSITION OF CHLORELLA; EFFECT OF ENVIRONMENTAL CONDITIONS. , 1949, Plant physiology.

[61]  F. K. Gleason,et al.  Site of action of the natural algicide, cyanobacterin, in the blue-green alga, Synechococcus sp. , 1984, Archives of Microbiology.

[62]  P. Falkowski,et al.  A novel mechanism for regulating the excitation of photosystem II in a green alga , 1987, Nature.

[63]  L. Laurens,et al.  Microalgae as biodiesel & biomass feedstocks: Review & analysis of the biochemistry, energetics & economics , 2010 .

[64]  Dana Carroll,et al.  Targeted mutagenesis using zinc-finger nucleases in Arabidopsis. , 2005, Proceedings of the National Academy of Sciences of the United States of America.

[65]  J. Harwood Membrane Lipids in Algae , 1998 .

[66]  A. Salamov,et al.  Green Evolution and Dynamic Adaptations Revealed by Genomes of the Marine Picoeukaryotes Micromonas , 2009, Science.

[67]  P. Siegenthaler,et al.  Lipids in Photosynthesis: Structure, Function and Genetics , 1998, Advances in Photosynthesis and Respiration.

[68]  E. Sherr,et al.  Significance of predation by protists in aquatic microbial food webs , 2004, Antonie van Leeuwenhoek.

[69]  A. Zarka,et al.  The host-range of Paraphysoderma sedebokerensis, a chytrid that infects Haematococcus pluvialis , 2009 .

[70]  T. Friedl,et al.  DISTINCTION BETWEEN MULTIPLE ISOLATES OF CHLORELLA VULGARIS (CHLOROPHYTA, TREBOUXIOPHYCEAE) AND TESTING FOR CONSPECIFICITY USING AMPLIFIED FRAGMENT LENGTH POLYMORPHISM AND ITS RDNA SEQUENCES 1 , 2005 .

[71]  P. Roessler,et al.  Changes in the activities of various lipid and carbohydrate biosynthetic enzymes in the diatom Cyclotella cryptica in response to silicon deficiency. , 1988, Archives of biochemistry and biophysics.

[72]  Li Dun-hai,et al.  Lysis of Aphanizomenon flos-aquae (Cyanobacterium) by a bacterium Bacillus cereus , 2006 .

[73]  C. Carrano,et al.  Photolysis of iron–siderophore chelates promotes bacterial–algal mutualism , 2009, Proceedings of the National Academy of Sciences.

[74]  Michael E. Himmel,et al.  Enzymatic conversion of biomass for fuels production. , 1994 .

[75]  John R. Benemann,et al.  BIOFIXATION OF CO 2 AND GREENHOUSE GAS ABATEMENT WITH MICROALGAE - TECHNOLOGY ROADMAP , 2003 .