Algae Produce More Biofuel When Starved of Nitrogen, But Why?

by Emil Morhardt

Algae, like all organisms, require nitrogen to produce amino acids, the building blocks of proteins, and necessary for DNA synthesis. When deprived of nitrogen, some species, such as the micro alga Chlamydomonas reinhardtii studied by Valledor et al. (2014), produce more lipids (oil) than normal, presumably as a stored energy source to tide them over until nitrogen again becomes available. These lipids could become the major source of biofuel if their production can be sufficiently ramped up. Valledor et al. wanted a better understanding of what was going on at the molecular level in the nitrogen-deprived algae so that they could eventually modify the species genetically to enhance oil production. They limited nitrogen, and quantified the changes in the cellular mix of protein and metabolic products (the proteome and metabolome), looking at the levels of over 1,200 proteins, 845 of which were recognized as enzymes mediating 157 known cellular metabolic pathways, half of those known for this species. Then they reintroduced nitrogen and followed the process further. Continue reading