Yeast, xylanase production

Xylan fragments induced xylanase also in non-cellulolytic microorganisms like Streptomyces sp. (71) and yeasts of the genus Cryptococcus and Trichosporon (72-74). In these strains xylanase could be efficiently induced also by methyl P-D-xylopyranoside, which is extremely slowly metabolized in the cells (72-74). TTie glycoside accelerated xylanase production in hyperproducing color variants of A. pullu-lans (75) and in several strains of Aspergillus (70). Low cost and easy preparation of methyl p-D-xylopyranoside favors its use for large-scale xylanase production. 

Xylanase production has been reported to occur in a wide spectrum of organisms. Although absent in vertebrate animals, xylanases are produced in many forms of bacteria, fungi and yeasts, crustaceans, algae and plant seeds. Current interest in xylanases has been focused primarily on the enzymes produced by fungi and bacteria and, to a lesser extent, yeasts. The high yields and relative ease of production have made these systems the most promising for future commercialization. 

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). 

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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