The invention discloses a biocatalytic oxidation. There is provided a method of oxidising at least one organic substance in aerobic conditions to produce at least one alcohol, amine, acid, aldehyde, and/or ketone, the method comprising: (a) producing ethanol and/or acetate from acarbon source in aerobic conditions, comprising (i) contacting the carbon source with a reaction mixture comprising a first acetogenic microorganism in an exponential growth phase; free oxygen; and a second acetogenic microorganism in a stationary phase, wherein the first and second acetogenic microorganism is capableof converting the carbon source to the acetate and/or ethanol; and (b) contacting the acetate and/or ethanol from step (a) with the organic substance and with a third microorganism capable of oxidising the organic substance to produce the alcohol, amine, acid, aldehyde, and/or ketone and wherein the acetate is a co-substrate.