Schematic representation of possible d-xylose and l-arabinose catabolic pathways in C. acetobutylicum. xylT (cac1345), d-xylose transporter; xylA (cac2610), d-xylose isomerase; xylB (cac2612), xylulokinase; araE (cac1339), l-arabinose transporter; araA (cac1342, cac1346), l-arabinose isomerase; araB (cac1344?), l-ribulokinase; araD (cac1341), l-ribulose-5-phosphate 4-epimerase.