Production of β-Glucosidase by Aspergillus niger on Wheat Bran and Glycerol in Submerged Culture: Factorial Experimental Design and Process Optimization

Abstract

The goal of this study was to develop a fermentation process for the production of β-glucosidase, an important enzyme in the hydrolysis of lignocellulose and has many applications in food and flavor industries, using low-cost agricultural residues as substrates. Based on statistical experimental design, high-titer production of β-glucosidase on wheat bran and glycerol by Aspergillus niger in a submerged culture was achieved. A 2-level Plackett-Burman design was first used to screen the bioprocess parameters affecting β-glucosidase production. Among the tested parameters, the concentrations of wheat bran, glycerol, corn steep liquor and KCl showed significant effects on β-glucosidase production. These four medium components were further optimized using a 3-level Box-Behnken design, and their optimal levels were found to be: wheat bran, 3.5 g/L; glycerol, 5 g/L; KCl, 0.1 g/L and corn steep liquor, 7.5 g/L, giving a high βglucosidase titer of 9.37 IU/ml, 1.6-fold of the maximum level obtained in the screening experiment. With the optimized medium, 5.41 IU/ml of β-glucosidase was produced in a stirred-tank bioreactor inoculated with a spore suspension. When the reactor was inoculated with precultured cell pellets and operated at optimized agitation (450 rpm) and aeration rates (2 vvm), β-glucosidase production increased to 9.33 IU/ml, which was comparable to the level obtained in shake-flasks. This study demonstrated a scalable fermentation process for the production of β-glucosidase on low-cost wheat bran and glycerol, which should have important industrial applications.

Optimization of cultivation conditions in banana wastes for production of extracellular β-glucosidase byTrichoderma harzianumRifai efficient forin vitroinhibition ofMacrophomina phaseolina

“…The studies reported that the activities of b-glucosidase produced by both these fungi peaked when the pH of the broth cultures was maintained at pH 5. In fact, the preferred neutral optimal pH in the broth cultures of T. harzianum is similar to that reported for an A. niger isolate [51].…”

Production of Biomass-Degrading Enzymes by Trichoderma reesei Using Liquid Hot Water-Pretreated Corncob in Different Conditions of Oxygen Transfer

“…Fontana et al [42] observed a minimum pH of 2.7 in a STB, reaching 5.10 at the end of the fermentation process by Aspergillus oryzae. This drop in pH Abdella et al [55] Peniciliium echinulatum S1M29 Cellulose plus glycerol Schneider et al [56] BGL beta-glucosidase activity, BXL beta-xylosidase activity, LHW-pretreated CC corncob pretreated by liquid hot water, OPEFB oil palm empty fruit bunch, DSB sugarcane bagasse pretreated by steam followed by delignification with NaOH, MC microcrystalline cellulose, n.d. not determined a Medium also containing sucrose, soybean meal, wheat bran in lower concentrations The values presented correspond to mean values of two replicate experiment could be related to the production of acid metabolic by-products, as well as with the acetic acid released from hemicellulose during the degradation of the lignocellulosic substrate by the produced xylanases. Similar trend in pH decrease was also reported by Khanahmadi et al [47] and Abdella et al [48].…”

Characterization of aromas of instant oolong tea and its counterparts treated with two crude enzymes from Aspergillus niger

“…As a result, exquisite processes have been developed to culture A. niger strains in an effort to yield natural food‐grade enzymes (Aguilar, Augur, Favela‐Torres, & Viniegra‐González, ). Researchers have shown that A. niger can grow on some agricultural byproducts such as potato, jamun leaves, tea wastes (TW), and wheat bran (WB), and synthesize multiple enzymes via fermentation (Abdella, Elsayed Mazeed, Yang, & Elbaz, ; Ni, Chen, et al, ; Wang, Ni, Cai, & Xiao, ). Recently, the crude enzymes prepared from A. niger via fermentation on TW medium and wheat bran and orange peel (WBOP) medium have been found in our preliminary tests to be able to change and improve the aroma profile of instant Oolong tea.…”

“…As a result, exquisite processes have been developed to culture A. niger strains in an effort to yield natural food-grade enzymes (Aguilar, Augur, Favela-Torres, & Viniegra-Gonz alez, 2001). Researchers have shown that A. niger can grow on some agricultural byproducts such as potato, jamun leaves, tea wastes (TW), and wheat bran (WB), and synthesize multiple enzymes via fermentation (Abdella, Elsayed Mazeed, Yang, & Elbaz, 2014;Wang, Ni, Cai, & Xiao, 2012).…”