Influence of temperature on the properties of the xylanolytic enzymes of the thermotolerant fungus Aspergillus phoenicis

Abstract

This study reports on the effects of growth temperature on the secretion and some properties of the xylanase and beta-xylosidase activities produced by a thermotolerant Aspergillus phoenicis. Marked differences were observed when the organism was grown on xylan-supplemented medium at 25 degrees C or 42 degrees C. Production of xylanolytic enzymes reached maximum levels after 72 h of growth at 42 degrees C; and levels were three- to five-fold higher than at 25 degrees C. Secretion of xylanase and beta-xylosidase was also strongly stimulated at the higher temperature. The optimal temperature was 85 degrees C for extracellular and 90 degrees C for intracellular beta-xylosidase activity, independent of the growth temperature. The optimum temperature for extracellular xylanase increased from 50 degrees C to 55 degrees C when the fungus was cultivated at 42 degrees C. At the higher temperature, the xylanolytic enzymes produced by A. phoenicis showed increased thermostability, with changes in the profiles of pH optima. The chromatographic profiles were distinct when samples obtained from cultures grown at different temperatures were eluted from DEAE-cellulose and Biogel P-60 columns.

Production of xylanase by Aspergilli using alternative carbon sources: application of the crude extract on cellulose pulp biobleaching

“…1b). This result suggested a thermotolerant character for A. fumigatus, as previously reported for A. phoenicis [2,6] and A. caespitosus [8]. For other Aspergillus species, such as A. awamori, A. niger, A. nidulans, A. oryzae and A. tamari, the best xylanase production occurs when the fungi are grown at lower temperatures [4].…”

“…In the last decades, an increased number of studies were devoted to the biobleaching of cellulose pulp [1][2][3][4][5][6][7][8][9]. In order to induce xylanase synthesis from microbial sources, agricultural residues, such as rye Xakes, wheat bran, oat Xakes, corn Xakes, crushed corncob, rice straw, sugar cane bagasse and others can be used [4,8].…”

<b>Reuse of wastewater from pulp industry for the optimization of fungal xylanase production

“…The best temperatures for fungal xylanases lie between 30 and 60°C. Higher temperatures are usually associated with a short period production, unlike conditions in current study, where high temperatures were associated with a long period of production (7 days) with negative influence of the 40-60°C temperature range, indicating the mesophilic characteristic of A. niger used (Rizzatti, Sandrim, Jorge, Terenzi, & Polizeli, 2004;Chandra & Sankhwar, 2011;De Alencar Guimarães et al, 2013;Pérez-Rodríguez et al, 2014).…”

Xylanases from Aspergillus niger, Aspergillus niveus and Aspergillus ochraceus produced under solid-state fermentation and their application in cellulose pulp bleaching

“…For this reason, different lignocellulolytic residues, such as wheat bran and other agro-wastes, have been used as growth substrates to produce high yields of xylanolytic enzymes using solid state fermentation (SSF). Fungal xylanolytic enzymes have received a great deal of attention in the last years, and a large number of different Aspergillus species have been reported as good producers of xylanases [1,[6][7][8][9]. The aim of this work was to describe the xylanases produced by strains of Aspergillus niger, A. niveus, and A. ochraceus with different characteristics from those described in the literature [1,9,10], to investigate the effect of environment and nutritional parameters on xylanase production and to analyze the effect of the biobleaching on eucalyptus pulp using these fungal xylanases.…”