1 This is the authors’ version of a manuscript that has been published in Biotechnology & Bioengineering (2002) volume 79, pages 154-164. Development of (R)-4-hydroxymandelonitrile synthesis in an aqueous-organic biphasic stirred tank batch reactor Running title: Development of (R)-4-hydroxymandelonitrile synthesis W.F. Willeman 1 , R. Neuhofer 2 , I. Wirth 2 , P. Pöchlauer 2 , A.J.J. Straathof 1 and J.J. Heijnen 1 1 Delft University of Technology, Kluyver Laboratory for Biotechnology Julianalaan 67, NL-2628 BC Delft, The Netherlands Tel.: +31-15-278-2330; fax.: +31-15-278-2355; e-mail: straathof@stm.tudelft.nl 2 DSM Fine Chemicals Austria, Research and Development, P.O. Box 933, A-4021 Linz, Austria