Seventeen different strains of filamentous fungi were grown in batch cultures to compare their abilities for the production of beta-fructofuranosidase. Three of them, Aspergillus oryzae IPT-301, Aspergillus niger ATCC 20611 and strain IPT-615, showed high production with total fructosyltransferase activity higher than 12,500 units l(-1). In addition, the beta-fructofuranosidases of those strains have a high fructosyltransferase activity-to-hydrolytic activity ratio. The temperature and pH effects on the sucrose-beta-fructofuranosidase reaction rate were studied using a 2(2) factorial experimental design. The comparative analysis of the tested variable coefficients shows that the variable pH contributes mostly to the changes in the fructosyltransferase and hydrolytic rates and in the V (t)/V (h) ratio. At 40 and 50 degrees C, there were no significant differences between the fructosyltransferase and hydrolytic velocities of these enzymes.

β-fructofuranosidase (EC 3.2.1.26) from Aspergillus sp 27H isolated from soil was investigated for production of fructooligosaccharides (FOS) using whole cells. It possesses hydrolytic and transfructosylating activities that can be altered by modifying the reaction conditions. The optimal conditions for the transfructosylating activity occur in the pH range 5.5-6.0 and at 60• C, while hydrolytic activity was highest at pH 4.0 and 55• C. At low sucrose concentration (10 g dm −3 ) there was rapid conversion of sucrose to glucose and fructose and very low concentrations of FOS were obtained. However, at sucrose concentrations higher than 216 g dm −3 the concentrations of hydrolysis products were reduced. Under the following conditions: pH 5.5, temperature 40• C, sucrose concentration 615 g dmand enzyme concentration 20β-fructofuranosidase units g −1 of sucrose, the FOS concentration reached a maximum value of 376 g dm −3 (234 g dm −3 1-kestose and 142 g dm −3 nystose) and the proportion of FOS in the solids in the reaction mixture was 600-620 g kg −1 at 6 h. These results suggest that β-fructofuranosidase from Aspergillus sp 27H could be an appropriate enzyme for the commercial production of FOS.

Aspergillus oryzae IPT-301, previously reported as a β-fructofuranosidase producing microorganism, was successfully mutated using UV irradiation at 253.7 nm followed by the screening of survivors resistant to certain stress conditions. Strains were first subjected to the β-fructofuranosidase activity assay using a portion from the colony grown in Petri dish as the enzyme source. Seven mutants with β-fructofuranosidase activity values relative to the parent culture between 140 -190% were selected from survivors grown at temperature of 40ºC or 0.018% (w/v) sodium dodecyl sulfate concentration. They were cultivated on a rotary shaker to characterize mycelium and extracellular fructosyltransferase activities.Three mutants named IPT-745, IPT-746 and IPT-748 showed the highest amount of mycelium activity whose values increased 1.5 -1.8 fold, compared with the parent strain. It was found that more than 55% of total enzyme activity (mycelium-plus extracellular-activity) from these strains was detected in the mycelium fraction. Only one mutant, IPT-747, exceeded the amount of extracellular enzyme exhibited by the parent strain (1.5 times). This mutant also showed the highest value of total fructosyltransferase activity.

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