Methods and procedures for designing and constructing microbes with the ability to harvest light energy are described. In certain embodiments, these methods and procedures are used to construct a photosynthetic yeast based on proteorhodopsin (PR) expression. Proteorhodopsin is a light powered proton pump used by some ocean bacteria to scavenge light energy. By illuminating single yeast cells expressing PR, controlled amounts of energy can be delivered to these cells. A light-harvesting yeast is a unique bioenergetics research platform for investigating the interplay of biofuel production, cellular ATP levels, and the proton-motive-force (pmf). Also, a strain of yeast with light-boosted biomass to biofuel conversion efficiency possesses direct industrial and commercial utility.
STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
 This work was supported in part by Contract No. DE-AC02-05CH11231 awarded by the US Department of Energy. The U.S. government has certain rights in the invention.