Metabolic Engineering and Synthetic Biology in Biohydrogen Production

Hydrogen is a well-accepted clean fuel which is gradually replacing the conventional fossil fuels, and biohydrogen is a net zero fuel produced via biophotolysis, photofermentation, dark fermentation and microbial electrolysis cell. Commercialization of biohydrogen production is not yet realized due to its low yield and high production cost as compared to hydrogen produced from conventional methods. Modification of metabolic pathways, microorganisms and enzymes involved can lead to increase in biohydrogen yield and also eliminate the production of other undesired metabolites. Moreover, in order to overcome the disadvantages due to oxygen sensitivity of the hydrogenase and nitrogenase enzymes involved in hydrogen production, an in-depth analysis of the metabolic pathways is important. Metabolic flux balance analysis aids in understanding the complex metabolic pathways and to select specific genes for deletion in order to enhance hydrogen production. Flux models developed for hydrogen producing microorganisms can be used to accurately predict the hydrogen production, thereby minimizing the number of experiments required. This chapter presents an overview of metabolic engineering approach and synthetic biology tools developed to improve biohydrogen production.