The invention relates to a novel gassing system that can be used particularly but not exclusively in biotechnology for supplying oxygen to cells or microorganisms. The gassing system comprises a bubble column and a distributor. There is furthermore a fluid medium in the tank that is to be supplied with gas. A vector is used as a transport means for the gas. The gas is incorporated into the bubble column and taken up by the vector here. The vector is applied to the fluid surface in droplet form via the distributor, sinks down into the medium and releases a portion of the absorbed gas to the medium. There is a collection device on the floor of the tank wherein the vector drops coalesce and enter the bubble column again. The invention furthermore relates to a bioreactor comprising the novel gassing system. The invention furthermore relates to a method for gassing a fluid medium, preferably an aqueous suspension comprising cells or microorganisms.