Abstract: A bioreactor for cultivating phototrophic microorganism, includes a transparent upper plate and a lower plate, the upper plate being disposed above and spaced apart from the lower plate and defining therebetween a continuous cultivation volume having an inlet port and an outlet port, each of the plates including a plurality of parallel-facing deformations including peaks and troughs disposed in a regularly repeating geometric pattern. Further, a method of operating the bioreactor includes supplying a liquid culture of phototrophic microorganisms in the cultivation volume, supplying the microorganisms with nutrients, incubating the culture in daylight and harvesting at least one of the microorganisms and metabolites that have diffused into the culture medium are harvested.