A method for the microbial production of fermentation products from organic feedstock in a reactor (1, 21), wherein the organic feedstock contains or consists of at least one of the following organic substances: - polysaccharide, such as cellulose, hemicellulose or starch and - lignocellulose characterized by a. producing enzymes for the enzymatic degradation of organic feedstock by aerobic microorganism (12, 32) in an aerobic zone of a reactor, wherein the reactor (1, 21) contains an oxygen permeable membrane (8, 28) separating an oxygen supply compartment (10, 30), wherein the oxygen supplied to the oxygen supply compartment is dissolved in a liquid, from a fermentation compartment (11, 31), the oxygen permeable membrane (8, 28) contains a surface, which is facing the fermentation compartment (11, 31) and on which a biofilm (14, 34) is located, and the biofilm (14, 34) contains a consortium of at least two species of microorganisms, wherein the consortium contains two or three groups of strains of aerobic microorganisms (12, 32) located adjacent to the surface of the membrane in the aerobic zone of the fermentation compartment for the production of extracellular enzymes in situ, wherein said groups of microorganisms are: - a group of strains with at least one strain of aerobic microorganisms for the production of cellulases, - a group of strains with at least one strain of aerobic microorganisms for the production of amylases, and - a group of strains with at least one strain of aerobic microorganisms for the production of lignin-modifying enzymes, and the fermentation compartment (11, 31) further contains at least one strain of an anaerobic microorganism (13, 33) located in the biofilm on the membrane in an anaerobic zone of the fermentation compartment (11, 31) for the fermentation of fermentable sugars, wherein the at least one strain of aerobic microorganism is supplied with oxygen through the membrane (8, 28), and wherein in the fermentation compartment (11, 31) the following process steps take place: b. enzymatically degradating the organic feedstock to fermentable sugars with the aerobic microorganisms; c. fermentating of the fermentable sugars to fermentation products by the anaerobic microorganism (13, 33) in the anaerobic zone, and. d. removing the fermentation product from the fermentation compartment by transporting the fermentation products through the membrane (8, 28) into the oxygen supply compartment (10, 30), wherein the fermentation products passing the membrane and entering the oxygen supply compartment are dissolved in the liquid. - polysaccharide, such as cellulose, hemicellulose or starch and - lignocellulose a. producing enzymes for the enzymatic degradation of organic feedstock by aerobic microorganism (12, 32) in an aerobic zone of a reactor, wherein the reactor (1, 21) contains an oxygen permeable membrane (8, 28) separating an oxygen supply compartment (10, 30), wherein the oxygen supplied to the oxygen supply compartment is dissolved in a liquid, from a fermentation compartment (11, 31), the oxygen permeable membrane (8, 28) contains a surface, which is facing the fermentation compartment (11, 31) and on which a biofilm (14, 34) is located, and the biofilm (14, 34) contains a consortium of at least two species of microorganisms, wherein the consortium contains two or three groups of strains of aerobic microorganisms (12, 32) located adjacent to the surface of the membrane in the aerobic zone of the fermentation compartment for the production of extracellular enzymes in situ, wherein said groups of microorganisms are: - a group of strains with at least one strain of aerobic microorganisms for the production of cellulases, - a group of strains with at least one strain of aerobic microorganisms for the production of amylases, and - a group of strains with at least one strain of aerobic microorganisms for the production of lignin-modifying enzymes, and the fermentation compartment (11, 31) further contains at least one strain of an anaerobic microorganism (13, 33) located in the biofilm on the membrane in an anaerobic zone of the fermentation compartment (11, 31) for the fermentation of fermentable sugars, wherein the at least one strain of aerobic microorganism is supplied with oxygen through the membrane (8, 28), and wherein in the fermentation compartment (11, 31) the following process steps take place: - a group of strains with at least one strain of aerobic microorganisms for the production of cellulases, - a group of strains with at least one strain of aerobic microorganisms for the production of amylases, and - a group of strains with at least one strain of aerobic microorganisms for the production of lignin-modifying enzymes, - a group of strains with at least one strain of aerobic microorganisms for the production of amylases, and - a group of strains with at least one strain of aerobic microorganisms for the production of lignin-modifying enzymes, b. enzymatically degradating the organic feedstock to fermentable sugars with the aerobic microorganisms; c. fermentating of the fermentable sugars to fermentation products by the anaerobic microorganism (13, 33) in the anaerobic zone, and. d. removing the fermentation product from the fermentation compartment by transporting the fermentation products through the membrane (8, 28) into the oxygen supply compartment (10, 30), wherein the fermentation products passing the membrane and entering the oxygen supply compartment are dissolved in the liquid.