Characterization of Hemicellulolytic Enzymes Produced by Aspergillus niger NRRL 328 under Solid State Fermentation on Soybean Husks

Abstract

This manuscript describes the analysis of xylanase production by Aspergillus niger NRRL 328 in solid state fermentation (SSF) of soybean husks. A maximum value of extracellular xylanase activity of approximately 950 U g -1 was achieved after 96 h. Proteomic analyses performed on the enzymatic mixture responsible for the maximum value of xylanase activity in SSF revealed the presence of two xylanases. This xylanolytic mixture was partially purified and characterized. It followed Michaelis-Menten kinetics towards xylan, with a KM of 7.92 ±0.97 mg xylan/mL and a Vmax of 262.2 ± 27.8 g L -1 s -1 . The optimum pH for the enzyme is 5.3, and the optimal temperature is 50 °C. The enzyme retains 100% of its activity at 40 °C for at least 1 month. It shows very high stability in a broad pH range, with a half-life of 40 days at pH 5.3, pH 6.0, pH 6.5, pH 7.0, and pH 8.0.

Screening of Fungal Strains for Cellulolytic and Xylanolytic Activities Production and Evaluation of Brewers’ Spent Grain as Substrate for Enzyme Production by Selected Fungi

“…[25][26][27][28][29]. When compared with the xylanase production by SSF reported for other Aspergillus spp., the maximum value of U/mL achieved by A. niger LPB-334 was higher than some fungi [16,[29][30][31][32][33][34] and lower than others [25,35,36] (Table 2). As far as cellulase production is concerned, the maximum value achieved by A. niger LPB 334 was, in most cases, higher [29,32,33,[37][38][39] and only in a few cases lower [26,36] than reported for other Aspergillus strains (Table 2).…”

“…Spore suspension and pre-inoculum production of Aspergillus spp. were performed as reported in Montibeller Weingartner et al [16]. Approximately 10 7 spores g −1 were inoculated on 25 g of dry BSG, in 250 mL Erlenmeyer flasks, in duplicate.…”

“…The flasks were incubated statically at 30 • C for 16 days. Enzyme extraction was performed according to Montibeller Weingartner et al [16].…”

Bioreactors for lignocellulose conversion into fermentable sugars for production of high added value products

“…Several efforts are under way to improve both the molecular systems, hydrolytic enzymes (Amore et al 2012 , 2013 , 2015 ; Salmon et al 2014 ; Weingartner Montibeller et al 2014 ; Giacobbe et al 2014 ), and microorganisms (Liguori et al 2015 ; Ventorino et al 2015 ), and bioreactor systems adopted for the biomasses bioconversion process in order to solve the environmental and economical issues of the process (Wang et al 2011 ; Khoo 2015 ).…”