Professor Anastasios Melis
Anastasios Melis
Photosynthesis, Metabolic Engineering, BioEnergy
Professor & Faculty Biologist LBNL
111 Koshland Hall
Berkeley, California 94720
Phone 510.642.8166
Lab Phone 510.642.6209
Fax 510.642.4995
B.Sc.  University of Athens
Ph.D.  Florida State University
Postdoctoral training: Rijksuniversiteit Leiden, The Netherlands
Postdoctoral training: Carnegie Institution for Science, Stanford, CA
 
 

We study the photosynthesis of plants, microalgae, cyanobacteria, and photosynthetic bacteria. Approaches include biophysics and biochemistry of the process, molecular biology and genetics of the organisms, and scale ups for product generation. Applied aspects include diverting the flow of photosynthesis to generate high-value compounds instead of the normally produced sugars. Products of interest are biofuels, feedstock for the synthetic chemistry industry and pharmaceuticals. Our trademark is product generation directly from photosynthesis, bypassing the need to harvest and process the respective biomass.

Research

Photosynthetic Biofuels and Chemicals
Expertise and Philosophy

The expertise of the Melis lab is in the field of photosynthesis and metabolism. We work with land plants, microalgae, cyanobacteria, and non-oxygenic (anaerobic) photosynthetic bacteria. Our platform includes most aspects of photosynthesis, beginning with organism cultivation, the efficiency of light absorption and utilization, electron transport and biochemical energy generation, and chloroplast and cellular metabolism. Included are the biophysics and biochemistry of the process, the molecular biology and genetics of the organisms, as well as scale ups in the cultivation of the various organisms for product generation.

The concept of “Photosynthetic Biofuels”, envisioned and pioneered by us, entails the direct application of photosynthesis for the generation of biofuels, in a process where a single organism acts both as catalyst and processor, synthesizing and secreting ready to use fuels.

The lab contributed with a breakthrough in the field, when in 2000 we demonstrated, for the first time, how to divert the natural flow of photosynthesis in green microalgae and to sustainably generate hydrogen gas, instead of the normally produced oxygen. This technology is currently employed by many laboratories in several countries, and serves as the platform for further photobiological hydrogen production research in the field.

The Melis lab also pioneered and currently leads an international effort to improve, by up to 300%, the efficiency and productivity of photosynthesis in mass cultures under bright sunlight conditions. This is implemented upon genetically optimizing the size of the array of chlorophyll molecules that serve as antennae to absorb sunlight for the photosynthetic apparatus.

In 2010, the Melis lab pioneered yet a new platform for the renewable generation of isoprene (C5H8) hydrocarbons in cyanobacteria and microalgae, derived entirely from sunlight, carbon dioxide (CO2) and water (H2O), and generated immediately from the primary products of photosynthesis. The process of generating isoprene currently serves as a case study in the development of technologies for the renewable generation of a multitude of biofuels and other useful bio-products.

Hydrogen and hydrocarbon biofuels production via microalgal photosynthesis
Hydrogen and hydrocarbon biofuels may become the primary 21st century energy carriers in California and the nation. Modification of photosynthesis in green microalgae may permit the generation of these biofuels as clean, renewable and economically viable commodities. However, specific biological problems associated with a sustained, high yield photosynthetic production of these biofuels remain to be addressed.
Current Objectives:
  • Maximize the solar-to-chemical conversion efficiency of photosynthesis under mass culture conditions
  • Improve the continuity and yield of the green microalgal hydrogen and hydrocarbon production
  • Develop suitable photobioreactors for biofuels production.
Microalgae for Hydrogen & Hydrocarbon Biofuels Production

The Melis lab has developed cells with a truncated chlorophyll antenna size containing 0.15x10e9 Chl/cell, vs. fully pigmented cells that contain 1.0x10e9 Chl/cell. The goal of this project is to improve the solar-to-chemical conversion efficiency of photosynthesis under bright sunlight from the normally 3% in wild type to 30% in the truncated Chl antenna mutants.

AlgaeVisual demonstration of the effect of differential pigmentation in the cells of the green alga Dunaliella salina. Note the greater transmittance of light through the Chl-deficient culture (left-side bottle) and the strong absorbance of light by the fully pigmented cells (right-side bottle).
H2 AlgaeHydrogen production in a sealed (anaerobic) liquid culture of the green alga Chlamydomonas reinhardtii, showing the hydrogen bubbles as they emanate from the medium. (From Melis and Happe 2001)

Through its Oleomics™ Project, the Melis Lab seeks to identify and exploit biosynthetic pathways leading to hydrocarbon biofuels production by unicellular green algae. Employed in this project are Chlamydomonas reinhardtii, a model green microalga amenable to genetic manipulation, and Botryococcus braunii, a prolific lipid-accumulating unicellular green alga.

Genetic Maps

Genetic maps of wild type and IspS transformants, illustrating a strategy for heterologous transformation of cyanobacteria, and conferring volatile isoprene hydrocarbons production. (From Lindberg et al. 2010)

BT CoilA mechanically compressed Botryococcus braunii var. Showa microcolony, revealing droplets of triterpenoid botryococcene hydrocarbons (Btc-oil) squeezed from the “flattened” micro-colony toward the growth medium. (From Eroglu and Melis 2010)

 

Recent Publications

 

Lindberg P, Park S, Melis A (2010) Engineering a platform for photosynthetic isoprene production in cyanobacteria, using Synechocystis as the model organism. Metabol Engin 12:70-79
 
Eroglu E, Melis A (2010) Extracellular terpenoid hydrocarbon extraction and quantitation from the green microalgae Botryococcus braunii var. Showa. Biores Technol 101:2359-2366
 
Mitra M, Melis A (2010) Genetic and biochemical analysis of the TLA1 gene in Chlamydomonas reinhardtii. Planta 231:729-740
 
Aristilde L, Melis A, Sposito G (2010) Inhibition of photosynthesis by a fluoroquinolone antibiotic. Environ Sci Tech. 44:1444-1450
 
Melis A and Mitra M (2010) Suppression of Tla1 gene expression for improved solar energy conversion efficiency and photosynthetic productivity in plants and algae. United States Patent 7,745,696 (issued 29-June-2010)
 
Eroglu E, Okada S, Melis A (2011) Hydrocarbon productivities in different Botryococcus strains: comparative methods in product quantification. J Appl Phycol 23:763–775
 
Ort DR, Zhu X-G, Melis A (2011) Optimizing antenna size to maximize photosynthetic efficiency. Plant Physiol. 155(1):79-85 
 
Eroglu E, Melis A (2011) Photobiological hydrogen production: Recent advances and state of the art. Biores. Technol. 102:8403–8413
 
Blankenship RE, Tiede DM, Barber J, Brudvig GW, Fleming G, Ghirardi ML, Gunner MR, Junge W, Kramer DM, Melis A, Moore TA, Moser CC, Nocera DG, Nozik AJ, Ort DR, Parson WW, Prince RC, Sayre RT (2011) Comparing photosynthetic and photovoltaic efficiencies and recognizing the potential for improvement. Science 332:805-809
 
Melis A (2011) Short chain volatile hydrocarbon production using genetically engineered microalgae, cyanobacteria or bacteria. United States Patent 7,947,478 (green microalgae; issued 24-May-2011)
 
Bentley FK, Melis A (2012) Diffusion-based process for carbon dioxide uptake and isoprene emission in gaseous/aqueous two-phase photobioreactors by photosynthetic microorganisms. Biotech Bioeng 109:100-109 
 
Mitra M, Ng S, Melis A (2012) The TLA1 protein family members contain a variant of the plain MOV34/MPN domain. Amer J Biochem Mol Biol. 2(1): 1-18
 
Melis A (2012) Photosynthesis-to-Fuels: From sunlight to hydrogen, isoprene, and botryococcene production. Energy Environ. Sci. 5(2): 5531-5539
 
Kirst H, Garcia-Cerdan JG, Zurbriggen A, Melis A (2012) Assembly of the light-harvesting chlorophyll antenna in the green alga Chlamydomonas reinhardtii requires expression of the TLA2-CpFTSY gene. Plant Physiol 158: 930–945
 
Mitra M, Dewez D, García-Cerdán JG, Melis A (2012) Polyclonal antibodies against the TLA1 protein also recognize with high specificity the D2 reaction center protein of PSII in the green alga Chlamydomonas reinhardtii. Photosynth Res 112:39-47
 
Melis A (2012) Short chain volatile hydrocarbon production using genetically engineered microalgae, cyanobacteria or bacteria. United States Patent 8,133,708 (cyanobacteria; issued 13-Mar-2012)
 
Zurbriggen A, Kirst H, Melis A (2012) Isoprene production via the mevalonic acid pathway in Escherichia coli (Bacteria). BioEnergy Res 5(4): 814-828, DOI 10.1007/s12155-012-9192-4
 
Hong S-Y, Zurbriggen A, Melis A (2012) Isoprene hydrocarbons production upon heterologous transformation of Saccharomyces cerevisiae. J Appl Microbiol 113: 52-65
 
Xie D-Y, Melis A (2012) Special Issue on metabolic plant biology (Editorial). Planta 236:763–764
 
Kirst H, Garcia-Cerdan JG, Zurbriggen A, Ruehle T, Melis A (2012) Truncated photosystem chlorophyll antenna size in the green microalga Chlamydomonas reinhardtii upon deletion of the TLA3-CpSRP43 gene. Plant Physiol. 160(4):2251-2260
 
Mitra M, Kirst H, Dewez D, Melis A (2012) Modulation of the light-harvesting chlorophyll antenna size in Chlamydomonas reinhardtii by TLA1 gene over-expression and RNA interference.  Phil. Trans. R. Soc. B 367:3430-3443
 
Bentley FK, García-Cerdán JG, Chen H-C, Melis A (2013) Paradigm of monoterpene (β-phellandrene) hydrocarbons production via photosynthesis in cyanobacteria. BioEnergy Res. 6:917–929; DOI: 10.1007/s12155-013-9325-4
 
Melis A (2013) Carbon partitioning in photosynthesis. Curr Opin Chem Biol. 17:453–456; http://dx.doi.org/10.1016/j.cbpa.2013.03.010
 
Chen H-C, Melis A (2013) Marker-free genetic engineering of the chloroplast in the green microalga Chlamydomonas reinhardtii. Plant Biotech J. 11: 818–828; DOI: 10.1111/pbi.12073
 
Kirst H, Melis A (2014) The chloroplast Signal Recognition Particle pathway (CpSRP) as a tool to minimize chlorophyll antenna size and maximize photosynthetic productivity. Biotechnology Advances 32: 66–72
 
Bentley FK, Zurbriggen A, Melis A (2014) Heterologous expression of the mevalonic acid pathway in cyanobacteria enhances endogenous carbon partitioning to isoprene. Molecular Plant 7:71-86
 
Formighieri C, Melis A (2014) Regulation of β‑phellandrene synthase gene expression, recombinant protein accumulation, and monoterpene hydrocarbons production in Synechocystis transformants. Planta DOI: 10.1007/s00425-014-2080-8 in press
 
Kirst H, Formighieri C, Melis A (2014) Maximizing photosynthetic efficiency and culture productivity in cyanobacteria upon minimizing the phycobilisome light-harvesting antenna size. Biochim Biophys Acta - Bioenergetics DOI: 10.1016/j.bbabio.2014.07.009 in press
 

Honors and Awards

Election to the rank of Fellow, American Association for the Advancement of Science - 2011
Research Achievement Award - US Department of Energy, Hydrogen Program - 2004
University Research Award - DaimlerChrysler Corporation - 2003
Distinguished Teaching Award - College of Natural Resources - 1994