Projects

The field of synthetic biology

The field of synthetic biology is rapidly

growing and evolving as it establishes itself

in the scientific community. Consequently,

the emergence of synthetic biology has been

increasingly reported in the press of different

countries. At this early stage, it is worthwhile

to note that the coverage of synthetic

biology varies from country to country;

with some countries emphasizing potential

risks or benefits, others focusing on future

applications, and still others examining the

social and ethical concerns that might arise as

the technology is developed.

BioHydrogen Generation by Genetically Engineered

Microorganisms

Engineering a Direct Pathway for Hydrogen Generation

James Swartz, Professor, Chemical Engineering; Alfred M. Spormann, Associate

Professor, Civil and Environmental Engineering, Biological Sciences, and Geological and

Environmental Sciences; Chia-Wei Wang, Postdoctoral Researcher, Chemical

Engineering; and Marcus Boyer and Keith Gneshin, Ph.D. Candidate Graduate

Researchers, Chemical Engineering

Introduction

The longterm goal for this project is to develop efficient and economical technology

for the biological conversion of solar energy into molecular hydrogen. The first portion

of the project (Part I) seeks to develop an organism/bioreactor system employing a

genetically engineered organism that is effective in the DIRECT conversion of sunlight to

hydrogen. The organism will use a shuttle protein, ferredoxin, to transfer electrons from

the reaction of water photolysis to the hydrogenase enzyme.

The following diagram (Figure 1) shows that this pathway is simple and short and

therefore offers attractive conversion efficiencies. The photosystem of a bacterium

such as Synechocystis captures sunlight and splits water to generate molecular oxygen,

protons, and mobilized electrons. These electrons are transferred to an electron carrying

protein, ferredoxin. We propose to introduce into the cyanobacterium a new hydrogenase

enzyme that will accept the electrons from ferredoxin and combine them with the protons

to make molecular hydrogen. However, the first and major problem is that existing

hydrogenase enzymes are inactivated by molecular oxygen. Thus, the initial focus is to

evolve a highly active hydrogenase to be resistant to inactivation by molecular oxygen.