Microalgae for Energy

Abstract

Algae are capable of switching their metabolism that is integrated with photosynthesis under certain conditions to produce H2gas and substrates for fuels such as biodiesel. H2is produced by microalgae under anaerobic conditions induced by sulfur deprivation as the most commonly applied treatment. Under these conditions, the demand for reducing electrons by the CO2fixation process is decreased making them available for H2production by algal O2‐senstive hydrogenase enzymes. The electrons are generated from water oxidation by the photosynthetic linear electron transfer and the oxidation of stored organic compounds such as starch. Biodiesel as fatty acid methyl esters can be produced from algal triacylglycerides by a transesterification process. The triacylglyceride synthesis in microalgae can be induced under stress conditions such as nitrogen (N) deprivation. Proteomic studies have shown that N stress can cause a shift in metabolism in favor of directing carbon skeletons toward fatty acid biosynthesis for triacylglyceride production. Several important factors limiting the potential of microalgae for biofuel production and their possible solutions, including the production of other fuels such as bioethanol and biomethane from algal biomass are also presented.