1. Laboratory of Microbial Ecology and Technology (LabMET), Faculty of Bioscience Engineering, Ghent University (UGent), Coupure Links 653, B-9000 Gent, Belgium, Laboratory of Food Chemistry, Wageningen University (WUR), P.O. Box 8129, 6700 EV Wageningen, The Netherlands, and Laboratory of Pharmacognosy and Phytochemistry, Faculty of Pharmaceutical Sciences, Ghent University (UGent), Harelbekestraat 72, B-9000 Gent, Belgium