Future Trends in Microelectronics: Up the Nano Creek

Guided Evolution in Interacting Microchemostat Arrays for Optimization of Photobacterial Hydrogen Production

R. H. Austin, P. Galajda, and J. Keymer

Dept. of Physics, Princeton University, Princeton, NJ 08540, U.S.A.

1.   Introduction

Microorganisms are incredibly sophisticated chemical factories that can transform, with great precision and efficiency, raw chemical energy (food) into the most directed and precise of products necessary for the organism’s survival in the particular ecological niche it finds itself. Microorganisms do not always need to eat food to survive: some have the ability to use not chemicals but light as an energy source. Although biological chemistry has attempted to deconstruct these remarkable factories with much success, and this is a worthy goal, a more opportunistic approach is simply to guide the intact factory in the cell through directed evolution towards an externally defined goal, that goal being the most efficient production of hydrogen gas (H₂) by the organism.

Ordinarily evolution experiments are done in chemostats that maintain a constant inflow of nutrients and outflow of waste in a stirred vessel containing a colony of bacteria or similar microorganism in solution. We wish to take the present chemostat design dramatically further by using our microfabrication technology to construct interacting arrays of chemostats, and then use our ability to sense the level of H₂ production within each microchemostat to punish colonies that have low H₂