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Microbial Production of Hydrogen

Microbial Production of Hydrogen. Dr. Bhavesh Patel Principal V.P. and R.P.T.P. Science College, Vallabh Vidyanagar Email- bhavesh1968@rediffmail.com. Outline. Importance of hydrogen production Types of hydrogen production Fermentative Photosynthetic The hydrogenase enzyme

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Microbial Production of Hydrogen

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  1. Microbial Production of Hydrogen Dr. Bhavesh Patel Principal V.P. and R.P.T.P. Science College, Vallabh Vidyanagar Email- bhavesh1968@rediffmail.com

  2. Outline • Importance of hydrogen production • Types of hydrogen production • Fermentative • Photosynthetic • The hydrogenase enzyme • Hydrogen production by Chlamydomonas reinhardtii • Research proposal

  3. Importance of Hydrogen as an Alternative Fuel • Increased levels of CO2 from fossil fuels cause an increase in the Greenhouse Effect • One of the detrimental effects of the Greenhouse Effect is Global Warming • Combustion of Hydrogen produces water, which is not detrimental to the environment

  4. Effects of Global Warming • Changes in climate • Sea level rise due to melting of polar icecaps • US seas rising 2.5-3.0mm/yr • By year 2050 it is most likely sea levels will rise by 15cm, but 1% chance they will rise one meter (Titus et al 1991) • One meter rise in sea level will cause $270-475 billion dollars in damage (Titus and Narayanam 1995)

  5. Microbial Hydrogen Production • Types of microbial hydrogen production • Fermentative • Photosynthetic (aerobic/anaerobic) • Most interest in hydrogen production research in US during the Energy Crisis of the 1970s • Interest in hydrogen production again in 1990s due to the awareness of Global Warming, etc.

  6. Fermentative Production of Hydrogen • Clostridia species - Clostridia beijerincki • Used in fuel cell that produced 15mA over 20 days using waste from alcohol distillery (Taguchi et al 1992) • Methanogens -Methanotrix soehngenii • Archeabacteria -Pyrococcus furiosus (hyperthermophile) • Eschericia coli - Formate Hydrogen Lyase pathway, which is inefficient

  7. Photosynthetic Production of Hydrogen • Purple Sulfur bacteria (Thiocapsa and Chromantium) • Non-Sulfur bacteria (Rhodospirillum and Rhodopseudomonas) • Green Algae (Chlamydomonas reinhardtii) • Advantages: • Photosynthetic organsims produce more hydrogen than fermentative organisms (Nandi and Sengupta 1998) • Photosynthetic organisms only require light and water

  8. The purple sulfur bacteria and the non-sulfur bacteria produce hydrogen through a reversible hydrogenase and as a by-product of denitrification. Chlamydomonas reinhardtii a green algae, produces hydrogen through hydrogenase. Hydrogenase is induced under anaerobic conditions Photosynthetic Hydrogen Production Mechanisms

  9. Hydrogenase • Many bacteria use it for H2 dissimulation to use the electrons for electron transport • Two types of hydrogenases • Nickel-Iron centered - dissimulate hydrogen • Iron-only centered - evolve H2

  10. Mechanism of Hydrogenase • Hydrogen Dissimulation • H2 Hydrogenase 2H+ + 2e- • Hydrogen Evolution • Fd-reduced + 2H+ Hydrogenase H2

  11. Comparison of Hydrogenase Yields Chlamydomonas has the highest hydrogen yield

  12. Advantages of UsingC. reinhardtii • Cheap and easy to grow • Requires fluorescent light and 5% CO2 • Grows at room temp. in water • Mutants have been isolated that are more energetically efficient (lack Photosystem I) • Research into its life cycle and flagella have yielded useful molecular techniques for studying the organism

  13. Chlamydomonas reinhardtii • Green-alga (eukaryotic) • Biflagellated, unicellular, photosynthetic • Reproduces asexually or sexually under adverse conditions

  14. Chlamydomonas reinhardtii

  15. C. reinhardtii Hydrogenase • Enzyme located in the chloroplast • Receives electrons from reduced ferrodoxin • Hydrogenase stimulated under anaerobic conditions (Happe et el 1994) • Hydrogenase inhibited by O2, which is produced by C. reinhardtii during photosynthesis

  16. Research Needs • Investigate hydrogenase oxygen inhibition • Investigate production of hydrogen by the Photosystem I mutant

  17. Research Proposal • Problem: Hydrogenase in C. reinhardtii inhibited by oxygen, which is made by the organism. • Solution: Determine Oxygen binding site on hydrogenase and create a clone with lower O2 binding and therefore higher H2 production.

  18. Research Approach • Isolate gene for hydrogenase (BAC library has recently become available) • Sequence the hydrogenase gene and determine the oxygen binding site. • Create hydrogenase clone that does not bind oxygen through site-directed mutagenesis. • Isolate hydrogenase deficient C. reinhardtii mutant through UV-mutagenesis. • Introduce mutant hydrogenase into hydrogenase deficient clone.

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