A photobioreactor apparatus in which a reaction chamber contains a slurry of water, nutrients and photosynthetic organisms. The sidewall of the reaction chamber is constructed of translucent material, thereby permitting light to be conveyed into the slurry to promote photosynthesis. The interior of the reaction chamber is in fluid communication with a gas dispenser. A lift member is disposed in the reaction chamber and gas is introduced in the slurry beneath the lift member, thereby providing buoyancy to lift the lift member, thereby providing agitation and movement of the slurry within the photobioreactor and enhancing growth of photosynthetic organisms.