The enzymatic transformation of water-insoluble reactants in nonaqueous solvents. Conversion of cholesterol to cholest-4-ene-3-one by a Nocardia sp. (Reprinted from Biotechnology and Bioengineering, vol 17, pg 815-826, 1975)

The rapid conversion of cholesterol to cholestenone by Nocardia in the pres ence of high proportions of water-immiscible solvent has been demonstrated. At high agitator speeds, the reaction rate was not limited by the rates of transfer of oxygen or cholesterol to the microorganisms. Using 100 g of th awed cells in 200 mi of carbon tetrachloride containing 16% (w/v) cholester ol, at 20 degrees C cholestenone was formed at 7 g/hr, Cells could be separ ated easily from the organic solvent and reused. After 7 runs (69 hr) the r eaction rate had fallen only to half the value for the first run.