Characterization and screening of algal strains for sustainable biohydrogen production: Primary constraints

Abstract

Algae have emerged as one of the most promising sources for biofuel production. In particular, microalgae can provide several different types of renewable biofuels like biodiesel, ethanol, and biohydrogen. Oxygenic photosynthesis splits water to release oxygen gas and uses the hydrogen atoms to drive the reduction of carbon dioxide to sugars. Under some circumstances, cyanobacteria are able to release the reductant as hydrogen gas. Hydrogen is an excellent source for fuel cells and has some attractive features such as three times more potentiality than ethanol. Algal communities including cyanobacteria can produce H2 through three main routes: (1) H2 production directly from native bidirectional hydrogenase, (2) H2 production from a native nitrogenase, and (3) H2 production from an introduced hydrogenase. Over the last decade or so, several new algal hydrogenases have been reported in literature, and efforts have been undertaken by manipulation of genetic pathways and metabolic engineering approaches. However, such approaches have shown constraints in terms of scale-up at the industrial level. This chapter highlights the aspect of metabolic engineering approaches and underlying constraints for biohydrogen production from algae. This chapter mainly discusses biohydrogen production potential of algae with a focus on understanding of biomass production, optimization of H2 production in response to strength of selected solution, and pH of the culture medium.