Improvement of a fed-hatch process for high level xylanase production by aBacillus strain

In this paper, the improvement of a fed-batch fermentation from the point o f view of an industrial xylanase production process is described. The Bacil lus strain chosen for this study is able to produce high quantities of a xy lanase that is suitable to be used as bleach boost agent hi chlorine-free b leaching sequences of paper. pulp, ft was found that xylo-oligosaccharides (hydrolysis products from xylan by xylanase action) were indispensable for induction of the enzyme synthesis, but that their presence in quantities of only 0.1 g dm(-3) xylose equivalents led to catabolite repression. A subst rate-limited fed-batch process, that is the most adapted, was furthermore I mproved with regard to nutrient requirement of the microorganism, especiall y the nitrogen source. A process with constant supply of a culture medium c ontaining xylan, peptone and mineral nitrogen was able to produce 20 240 nk at cm(-3) with a productivity of 910 nkat cm(-3)h(-1), which places the pro cess among the best ever reported. (C) 2001 Society of Chemical industry.