(480d) Towards an Autonomous Cyanobacterial Biorefinery: Continuous Production of Bio-Hydrogen and Biomass

Due to the rapid rise in global population, demands for food and energy have been projected to increase significantly over the coming decades [1, 2]. At the same time, increasing concerns over climate change have emphasized the need to transform current methods of food and energy production into more environmentally sustainable alternatives [3].

          Cyanothece sp. ATCC 51142, a unicellular nitrogen-fixing marine cyanobacterium, has been reported for its excellent nutritional value in terms of biochemical composition (50 – 60% protein dry weight) [4] as well as its high production rate of molecular hydrogen (H₂) [5], an energy carrier which has great potential to provide clean power needed for transport, heating and electricity [6], thereby appearing to be a promising microbial platform to address the above concerns.

In our presentation, we will report our advanced engineering approach (through the design of a novel photo-bioreactor system and the judicial determination of optimal cultivation conditions) to harness cyanobacterial platforms for the mass production of food and energy vectors. A two-stage chemostat photo-bioreactor system, which enables continuous co-production of H₂ and biomass, was demonstrated for thirty consecutive days [7]. This photo-bioreactor development offers significant improvements in hydrogen (5.5 fold) and biomass (2 fold) productivities over batch processes.

In addition, other pertinent factors that affect productivity such temperature and light intensity will be discussed [8]. We will conclude with the conceptual analysis of the merits of an autonomous cyanobacterial biorefinery.

1.            Bruinsma, J., The resource outlook to 2050: by how much do land, water and crop yields need to increase by 2050?, 2009, FAO.

2.         EIA, International Energy Outlook, 2011.

3.         EIA, Clean Energy Progress Report 2011, OECD/IEA: Paris.

4.         Schneegurt, M.A., et al., Compositional and toxicological evaluation of the diazotrophic cyanobacterium, Cyanothece sp strain ATCC-51142. Aquaculture, 1995. 134(3-4): p. 339-349.

5.         Bandyopadhyay, A., et al., High rates of photobiological H₂ production by a cyanobacterium under aerobic conditions. Nat Commun, 2010. 1: p. 139.

6.         Dunn, S., Hydrogen futures: toward a sustainable energy system. International Journal of Hydrogen Energy, 2002. 27(3): p. 235-264.

7.         Pongsathorn Dechatiwongse, Geoffrey Maitland and Klaus Hellgardt, Enhancements in H₂ and Biomass Productivity of Unicellular Cyanobacterium using a Two-Stage Chemostat Photobioreactor System (in preparation).

8.         Pongsathorn Dechatiwongse, Suna Srisamai, Geoffrey Maitland and Klaus Hellgardt, Effects of Light and Temperature on the Photoautotrophic Growth of the Hydrogen-Producing Cyanobacterium Cyanothece sp. ATCC 51142 Algal Research (under review), 2014.