Manipulating the generation of reactive oxygen species through intermittent hypoxic stress for enhanced accumulation of arachidonic acid-rich lipids.

Abstract: The accumulation of reactive oxygen species (ROS) can induce oxidative damage which can be detrimen- tal to microbial biomass and product yields. In this study, we used intermittent hypoxic stress (IHS) to eliminate the main source of ROS during the production of arachidonic acid (ARA)-rich lipids by Mortierella alpina. Biomass, lipid- and ARA concentration simultaneously reached their peak values, and the ARA yield increased by about 20% along with a lower level of ROS concentration. Under these con- ditions, more NADPH, substrate and energy may be available for lipid biosynthesis. The efficacy of this strategy was also confirmed in a bioreactor, with similar results. Interestingly, the total power required for stirring fell by about 4%, which may be of practical value for energy savings. This work offers new insights into the control of ROS generation in M. alpina and might be applicable to other microbial PUFAs producers.