Reactive oxygen species and their applications toward enhanced lipid accumulation in oleaginous microorganisms

Oleaginous microorganisms are among the most promising alternative sources of lipids for oleochemicals and biofuels. However, in the course of lipid production, reactive oxygen species (ROS) are generated inevitably as byproducts of aerobic metabolisms. Although excessive accumulation of ROS leads to lipid peroxidation, DNA damage, and protein denaturation, ROS accumulation has been suggested to enhance lipid synthesis in these microorganisms. There are many unresolved questions concerning this dichotomous view of ROS influence on lipid accumulation. These include what level of ROS triggers lipid overproduction, what mechanisms and targets are vital and whether ROS act as toxic byproducts or cellular messengers in these microorganisms? Here we review the current state of knowledge on ROS generation, antioxidative defense system, the dual effects of ROS on microbial lipid production, and ROS-induced lipid peroxidation and accumulation mechanisms. Toward the end, the review summarizes strategies that enhance lipid production based on ROS manipulation.