Xylanase Production by Aspergillus awamori in Solid-State Fermentation and Influence of Different Nitrogen Sources

Abstract

The use of purified xylan as a substrate for bioconversion into xylanases increases the cost of enzyme production. Consequently, there have been attempts to develop a bioprocess to produce such enzymes using different lignocellulosic residues. Filamentous fungi have been widely used to produce hydrolytic enzymes for industrial applications, including xylanases, whose levels in fungi are generally much higher than those in yeast and bacteria. Considering the industrial importance of xylanases, the present study evaluated the use of milled sugarcane bagasse, without any pretreatment, as a carbon source. Also, the effect of different nitrogen sources and the C:N ratio on xylanase production by Aspergillus awamori were investigated, in experiments carried out in solid-state fermentation. High extracellular xylanolytic activity was observed on cultivation of A. awamori on milled sugarcane bagasse and organic nitrogen sources (45 IU/mL for endoxylanase and 3.5 IU/mL for beta-xylosidase). Endoxylanase and beta-xylosidase activities were higher when sodium nitrate was used as the nitrogen source, when compared with peptone, urea, and ammonium sulfate at the optimized C:N ratio of 10:1. The use of yeast extract as a supplement to the these nitrogen sources resulted in considerable improvement in the production of xylanases, showing the importance of this organic nitrogen source on A. awamori metabolism.

Production of fibrolytic enzymes by Aspergillus japonicus C03 using agro-industrial residues with potential application as additives in animal feed

“…Peptone produced the best result for both enzymes, increasing 12 and 29% xylanase and cellulase activities, respectively. These results are in agreement with those reported in the literature where fungi were found to produce higher xylanase activities on organic nitrogen sources [25][26][27].…”

Production of xylanase under solid-state fermentation by Aspergillus tubingensis JP-1 and its application

“…Similar effects of moisture content on xylanase production have also been reported by other researchers [22,30]. High moisture enhanced fungal growth and subsequent early initiation of the enzyme production when lignocellulosic substrates were used as carbon sources [10,31].…”

“…Further incubation did not show any increment in the level of xylanase production. The production of xylanases using other substrates such as wheat bran, sugarcane baggase, corn cobs, soybean hull and rice straw has also been reported by other researchers [13,28,31]. Kheng and Omar [37] reported xylanase production of 35 U/g of palm kernel cake (PKC) using Aspergillus niger USM AI 1 under SSF system.…”

Ultrasounds pretreatment of olive pomace to improve xylanase and cellulase production by solid-state fermentation

“…Carbon and nitrogen sources are important components for fungal growth and should be given significant consideration (Rodríguez-Leon et al, 2008). The optimum C/N ratio for SSF is closed to 15 (Lemos et al, 2001), so that to achieve this value additional source of N should be added.…”