Herein disclosed is a method of processing a medium containing algae microorganisms to produce algal oil and by-products, comprising providing the medium containing algae microorganisms; passing the medium through a rotor-stator high shear device; disintegrating cell walls of and intracellular organelles in the algae microorganisms to release algal oil and by-products; and removing the algae medium from an outlet of the high shear device. In an embodiment, disintegration is enhanced by a penetrating gas capable of permeating the cell wall. In an embodiment, enhancement is accomplished by super-saturation of the penetrating gas in the medium or increased gas pressure in a vessel. In an embodiment, the penetrating gas is different from the gas produced by the cell during respiration. A suitable system is also discussed in this disclosure.