Repeated fed-batch culture methods

A method of producing oil comprising the steps of:

• (a) providing a container comprising one or more oil-producing microorganisms and medium, wherein the oil-producing microorganisms and medium form a start volume;
• (b) culturing the oil-producing microorganisms in the medium in the container under conditions that favor biomass production then lipid production until the oil-producing microorganisms in the medium completes fermentation and the medium reaches a threshold volume, wherein the threshold volume is greater than the start volume, and wherein culturing comprises feeding one or more carbon sources to the medium;
• (c) harvesting a portion of the threshold volume of the medium from the container to leave a residual volume that is 10% to 40% of the start volume;
• and
• (d) adding fresh medium to the container in an amount to return the volume of the medium to the start volume;
• (e) isolating the oil from the harvested portion of the threshold volume, wherein the oil comprises fatty acids and the fatty acids comprise docosahexaenoic acid (DHA);
• and
• (f) repeating steps (a) to (e) one or more times.