Inulooligosaccharides (IOS) production from chicory extract was carried out using endoinulinase obtained from a new isolate, Xanthomonas oryzae No. 5. The IOS production from chicory extract was maximum when 50 g/liter of chicory extract was utilized as the substrate. As the substrate concentration increased, the IOS production accordingly decreased probably due to substrate inhibition. For a comparative study, enzyme reactions were carried out from pure inulin as substrate. Though total IOS contents indicated higher IOS yield with pure inulin compared to that of chicory extract, the distribution of inulooligosaccharide components between pure inulin and chicory extract was not significantly different; i.e. DP5 and higher oligosaccharides are major products in case of both chicory extract and pure inulin as substrate. A considerable amount of oligofructose (about 30%, w/w), which were originally present in chicory extract, resulted in the change of the enzyme kinetics. A reaction pH 7 was found to be most suitable for enzyme reaction. The initial reaction rates increased with increasing enzyme dosage, although the relative composition of the IOS produced remain unchanged. (C) 2001 Elsevier Science Inc. All rights reserved.