The production of fructooligosaccharides
(FOS) and b-fructofuranosidase (FFase) by immobilized
cells of Penicillium expansum was evaluated. In an initial
stage, different low-cost materials including synthetic fiber,
polyurethane foam, stainless steel sponge, loofah sponge,
and cork oak were tested as carrier for the fungus immobilization.
Additionally, the influence of the inoculum age
(1 or 3 weeks) on cells immobilization, FOS and FFase
production was also verified. Synthetic fiber and polyurethane
foam were the best materials for P. expansum
immobilization (2.21 and 1.98 g/g carrier, respectively)
and FOS production (120.3 and 104.8 g/l), and gave also
high results of FFase activity (23.01 and 32.42 U/ml).
Then, the production of FOS and FFase by repeated batch
fermentation with P. expansum immobilized on synthetic
fiber was studied, aiming to improve the batch fermentation
results. The results obtained in this stage were very
promising with FOS yields of 87, 72, and 44 %, in the 3
initial cycles (60 h), respectively; the FFase activity was
constant throughout the process (6 cycles, 96 h). Repeated
batch fermentation with immobilized cells of P. expansum
was found as being a technology with great potential for
FOS and FFase production on industrial scaleThe financial support from FCT, the Portuguese Foundation for Science and Technology (research grant SFRH/BPD/38212/2007) is gratefully acknowledged
