Did you ever figure out where to purchase xylose isomerase? We are also looking. Thanks, Kirsty Kirsty A. Salmon, Ph.D. Manager/Project Scientist II Institute for Genomics & Bioinformatics University of California, Irvine Room 1309, CAL(IT)2 Campus Dr. Irvine, CA 92697-2800 ksalmon from uci.edu