The cyclohexanone monooxygenase (CHMO) from Acinetobacter calcoaceticus NCIMB 9871 has been cloned into Escherichia coli in an L-arabinose inducible vector. The recombinant E. coli containing the L-arabinose inducible CHMO was grown at 1.5 litres under controlled conditions to determine the parameters for growth and induction. It was found that induction with 0.1% (w/v) L-arabinose at late logarithmic phase of growth and growth for a further 2.5 to 3 h gave the optimal CHMO titre (similar to 3500 U.1(-1).630 U . g dry cell weight(-1)). High dissolved oxygen concentrations were shown to be deleterious to the CHMO titre. This influenced the strategy for growth and induction, and was optimal when the oxygen uptake rate was maximized but the dissolved oxygen concentration was zero. Finally, a 300 litre scale fermentation was carried out giving a total CHMO titre of >8 x 10(5) U. (C) 2001 Elsevier Science Inc. All rights reserved.