Use of a chemical inhibitor as an alternative approach to enhance lipid production in Chlamydomonas reinhardtii (Chlorophyceae)

Previously, the best ways of inducing oil production by algae was to remove the nitrogen source in the medium or to provide a fixed, small amount of N and allowing cells to enter a state of N depletion. These conventional methods for achieving N starvation are time consuming and expensive; therefore an alternative method is needed. Here we show that the chemical inhibitor of nitrogen assimilation, methionine sulfoximine (MSX), can be successfully used to rapidly induce conditions similar to nitrogen starvation in Chlamydomonas reinhardtii. This resulted in a twofold increase in lipid content. In addition, the MSX-treated cells are photosynthetically more competent compared with the conventional method for inducing N starvation. Although MSX is not the ideal inhibitor to use in commercial algal lipid production because of its toxicity to animals, this work serves as a proof of the concept that inhibitors might be used to provide a simpler, cost- and time-effective chemical approach to induce conditions leading to enhanced lipid production.