Hydrogen production by fermentative consortia

In this work, H 2 production by anaerobic mixed cultures was reviewed. First, the different anaerobic microbial communities that have a direct relation with the generation or consumption of H 2 are discussed. Then, the different methods used to inhibit the H 2-consuming bacteria are analyzed (mainly in the methanogenesis phase) such as biokinetic control (low pH and short hydraulic retention time), heat-shock treatment and chemical inhibitors along with their advantages/disadvantages for their application on an industrial scale. After that, biochemical pathways of carbohydrate degradation to H 2, organic acids and solvents are showed. Fourth, structure, diversity and dynamics of H 2-producers communities are detailed. Later, the hydrogenase structure and activity is related with H 2 production. Also, the causes for H 2 production inhibition are analyzed along with strategies to avoid it. Finally, immobilized-cells systems are presented as a way to enhance H 2 production.