Biotechnologie, Agronomie, Société et Environnement (Jan 2008)
Improvement of xylanase production by Penicillium canescens 10-10c in solid-state fermentation
Abstract
Among hemicellulases, xylanases are catalysts of considerable interest so as fundamental than applied point of view. However,it is paradoxical to note that the high cost of their production limits their use on a large scale. The use of purified xylan as culturesubstrate increases the production cost of the enzyme. Consequently, for commercial applications, it is advisable to developprocesses starting from inexpensive substrates. The purpose of this study is to optimise xylanases production in solid-statefermentation based on agricultural residues. The strain is Penicillium canescens 10-10c, selected in our laboratory for his abilityto produce xylanase activity free of cellulase. Assays concern optimization of different culture parameters in order to developin the future a solid-state fermentation reactor with soya oil cake. These parameters are: medium composition, temperatureincubation, induction and repression mechanisms. Soya oil cake in pellets (size > 10 mm) gave a higher enzymatic activity.Great volume of culture medium reduced the enzymatic production. The presence of lactose, saccharose or starch of corn hasa positive effect on the production of xylanase while the presence of xylose, mannose, galactose, arabinose, cellobiose andpectin or methylcellulose reduces the production of xylanase. The sources of phosphorus (di-potassic and di-sodic) enhancexylanase production. The enzymatic production obtained in Erlenmeyer flasks (250 ml) after 7 days incubation at 30°C isabout 14 000 U.g-1 of carbon source. The nature of inoculum affects the enzymatic productivity. Indeed, better productivitywas obtained with inoculation by solid preculture (956 U.g-1 per day) than liquid preculture (473 U.g-1 per day) and sporessuspension (383 U.g-1 per day). These observed enzymatic activity levels are higher than those related in the literature, whichshows all the potentialities of this strain and this technique for the production of xylanase and allow to develop our solid-statefermentation bioreactor.
