Aureobasidium pullulans has been a major source of fructosyltransferase (EC 2.4.1.9) for the production of fructooligosaccharides from sucrose. The organism is known to produce both intra and extra cellular FTase. The present study examines the effect of ultrasonication on the release of FTase from A. pullulans CFR 77, and subsequently on the enzymatic production of fructooligosaccharides. The acoustic power (W), and the processing time (min) were the chosen key elements to study their effect on the release of the enzyme. The release of the enzyme (FTase) was monitored by determining the OD at 275 nm, and the protein content of the fractions. The intracellular FTase obtained after the sonication was used for the production of FOS. The amount of FOS produced ranged from 57 to 59%. Based on the energy cost of he system, and the maximum amount of FOS produced, ultrasonication of the cells at acoustic power of 20 W for 9 min was found to be optimum. Thus, the study demonstrates the potential role of ultrasonication in efficient release of the intracellular FTase which can be used for the production of FOS, an industrially important prebiotic. (c) 2006 Elsevier Inc. All rights reserved.