The viability and C11beta-hydroxylation activity of Absidia coerulea were measured after treatment with compressed or supercritical CO2 and C2H4 under various initial pH and temperature conditions. The specific activity of A. coerulea on C11beta-hydroxylation can reach 23% and 75%, respectively, after treatment with 7.5 MPa of CO2 and C2H4, leading to the feasibility of enhancing both the solubility of the reactants and the beta-hydrocortisone yield for the hydroxylation of Reichsterin's substance acetate by using supercritical C2H4 as an alternative to the organic solvent.