Fungal xylanase production

Fungal xylanases including A. oryzae xylanase have been reviewed recently by Haltrich et al (8). Xylanases produced by A. oryzae have been already studied fi om different aspects. Induction of xylanase production by a synthetic xyiobiose anidog, ft-metiiyl-D-xyloside, was dmonstrated by Bailey et al (9). Purification and characterization of xylanase components was studied in detail (10,11). Xylanase production in a 10-1 laboratory fermenter was also performed (12). 

Gonjalves TA, Damasio ARL, Segato F, Alvarez TM, Bragatto J, Brenelli LB, Citadini APS, Murakami MT, Ruller R, Leme AFP, Prade RA, Squina FM. (2012). Functional characterization and synergic action of fungal xylanase and arabino-furanosidase for production of xylooligosaccharides. Bioresour Technol, 119, 293—299. 

In the treatment of cellulose pulps one essential criterion for a suitable enzyme preparation is that its cellulase activity should be as low as possible, or preferably absent completely. As even extremely low cellulase activities may ruin pulp quality, Trichoderma enzyme preparations are unlikely to be suitable for these applications. Many bacterial and fungal enzymes with low cellulase activity have been shown to be suitable for treatment of pulps 14, 15, 16,17), Regulation of the often synchronous production of cellulolytic and hemicellulolytic enzymes in micro-organisms is not well understood, and is further complicated by substrate cross-specificity of these enzymes. Enzymes with both endoglucanase and xylanase activity have been reported for bacteria 18, 19) and fungi 20, 21, 22), In addition to selection of strain and... 

Similar approaches to cloning of bacterial xylanases have been used for genes from Clostridium acetobutylicum (30), Bacillus polymyxa (31), Bacteroides succinogenes (32), Clostridium thermocellum (33) and Pseudomonas fluorescens subsp. cellulosa (34). In each case the xylanases were predominantly located intracellularly and the levels of xylanases produced from cloned systems were, in general, very low in comparison to yeast and fungal systems. A comparison of the production yields and extent of extracellular production for various cloned xylanase genes is found in Table... 

The use of filamentous fungi for production of xylanases was initially attractive because the enzymes are released extracellularly thus eliminating the need for cell lysis procedures. In addition, xylanase levels in fungal culture filtrates are typically in much higher concentrations than from yeasts and bacteria. Many examples of xylanases produced from fungi are listed in the review by Dekker (41). 

It has been proposed that the production of xylanases and cellulases is under separate regulatory control in some filamentous fungi (1). Hrmova et al. (42) reached a similar conclusion after monitoring the daily production of these enzymes in Trichoderma reesei QM 9414. Xylanase and cellulase activities followed independent production profiles during fungal growth. The same effect has been observed in batch cultures of T. harzianum. We have observed peak xylanase activity on the third day of growth whereas the cellulase activity peaked after day five or six (unpublished). 

These references contain a comprehensive list of bacterial and fungal strains and species that have been screened for the production of D-xylanase, but that are too numerous to include in this Table. 

The Degradation Products Arising from the Hydrolysis of D-Xylans by Endo-D-xylanases of Fungal Origin... 

Berrin, J.G., Williamson, G., Puigserver, A., Ghaix, J.C., McLauchlan, W.R., Juge, N., 2000. High-level production of recombinant fungal endo-p-1, 4-xylanase in the methylotrophic yeast Pichia pastoris. Protein Expression and Purification 19 (1), 179-187. 

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