Unstable fuel prices and increased pressure to lower dependency on fossil fuel drive efforts to produce biofuels by microbial fermentation of biomass. In comparison to other feedstocks, algae can provide a high-yield source of biofuels without compromising food supplies, rainforests or arable land. Green seaweeds represent an important biomass that can easily be cultured. Among the polymers synthesized by these species, cell wall polysaccharides represent around 38-54% of the dry algal matter. The leading approach for converting biomass into ethanol is based on microbial fermentation. This methodology takes advantage of the vast enzymatic and metabolic machineries present in microbial genomes, which allow multiple reactions to take place under fairly mild conditions (temperature, pressure, pH etc.). In addition, the advances in microbial metabolic and enzymatic engineering enabled the further expansion of the range of biomass that can be fermented. Our lab exploits these new tools and aims to develop a bacterial system that can convert the biomass of the green algae, Ulva sp., to ethanol. In order to construct a consolidated bio-process that transforms the Ulva polysaccharides into ethanol, major challenges must be addressed. The first is identification and cloning of the enzymatic machinery required for the saccharification of the polysaccharides into monosaccharides. The second challenge is to engineer the bacterium to transport the monosaccharides into the cell and metabolize them into ethanol. By mining the genome of bacteria that can degrade Ulva we have already been able to identify and express several new enzymes that are required for the degradation of complex algal polysaccharides and to improve the fermentation of the monomers by metabolic engineering of ethanologenic strain.