Hydrogen production by fermentative consortia

In this work, H2 production by anaerobic mixed cultures was reviewed. First, the different anaerobic microbial communities that have a direct relation with the generation or consumption of H2 are discussed. Then, the different methods used to inhibit the H2-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 H2, organic acids and solvents are showed. Fourth, structure, diversity and dynamics of H2-producers communities are detailed. Later, the hydrogenase structure and activity is related with H2 production. Also, the causes for H2 production inhibition are analyzed along with strategies to avoid it. Finally, immobilized-cells systems are presented as a way to enhance H2 production.