Method for collecting seed algae from microalgae on liquid surface, and for performing culturing in separate culture vessel, in method for culturing microalgae on liquid surface
Provided is a method for culturing microalgae that makes it possible to reduce the production cost of a biomass derived from microalgae. A method for culturing microalgae, including: a first-stage culture whereby a biofilm in the form of a film-shaped structure or three-dimensional structure composed of microalgae is formed on the liquid surface of a culture broth by culturing microalgae, obtained via a microbial purification step, in the culture broth in a first culture vessel； and a second-stage culture whereby the microalgae are cultured on the liquid surface of the culture broth by using, as seed algae, at least some of the biofilm in the form of a film-shaped structure or three-dimensional structure formed on the liquid surface.
