PRODUCTION OF FUNGAL XYLANASES

Applications of xylanases can be found in the food feed and pulp/paper industry. Filamentous fungi are particularly interesting producers of this enzyme from an industrial point of view, due to the fact that th ey excrete xylanases into the medium. Furthermore, xylanase levels fro m fungal cultures are generally much higher than those from yeasts or bacteria. In addition to xylanase, fungi typically produce several acc essory xylanolytic enzymes, which are necessary for debranching substi tuted xylans. An important factor for efficient xylanase production is the choice of ail appropriate inducing substrate, either insoluble or soluble, as well as optimization of the medium composition. In additi on, the substrate can influence the concomitant formation of celluloly tic enzymes in certain organisms. Bioprocess parameters, that can affe ct activities and productivities of xylanase attained in a fermentatio n process, as well as the concurrent formation of cellulases, include the pH, temperature, or agitation. Xylanase activities produced by dif ferent organisms, including filamentous fungi and yeasts, are compared for both submerged and solid-state fermentations. When available darn on the concurrent formation of cellulolytic enzyme activities are inc luded. On an industrial scale, xylanases are produced mainly by Asperg iilus and Trichoderma spp. A list of commercially available xylanases and their potential applications is given. Copyright (C) 1997 Elsevier Science Ltd.