Production and Characterization of Highly Thermostableβ-Glucosidase during the Biodegradation of Methyl Cellulose byFusarium oxysporum

Abstract

Production of β-glucosidase from Fusarium oxysporum was investigated during degradation of some cellulosic substrates (Avicel, α-cellulose, carboxymethyl cellulose (CMC), and methylcellulose). Optimized production of β-glucosidase using the cellulosic substrate that supported highest yield of enzyme was examined over 192 h fermentation period and varied pH of 3.0–11.0. The β-glucosidase produced was characterized for its suitability for industrial application. Methyl cellulose supported the highest yield of β-glucosidase (177.5 U/mg) at pH 6.0 and 30°C at 96 h of fermentation with liberation of 2.121 μmol/mL glucose. The crude enzyme had optimum activity at pH 5.0 and 70°C. The enzyme was stable over broad pH range of 4.0–7.0 with relative residual activity above 60% after 180 min of incubation. β-glucosidase demonstrated high thermostability with 83% of its original activity retained at 70°C after 180 min of incubation. The activity of β-glucosidase was enhanced by Mn2+ and Fe2+ with relative activities of 167.67% and 205.56%, respectively, at 5 mM and 360% and 315%, respectively, at 10 mM. The properties shown by β-glucosidase suggest suitability of the enzyme for industrial applications in the improvement of hydrolysis of cellulosic compounds into fermentable sugars that can be used in energy generation and biofuel production.

Characterization of thermophilic fungi producing extracellular lignocellulolytic enzymes for lignocellulosic hydrolysis under solid-state fermentation

“…7a. Hence, declining in enzyme activity with the further increase in temperature could be due to denaturation by heat (Olajuyigbe et al 2016). Figure 7b depicts the crude cellulase retained 80% of its initial activity in first 20 min of incubation at 60 °C, but this gradually decreased in the next 40 min, providing a maximum of 65-70% activity after 40 min.…”

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

“…It is known that b-glucosidase activity tends to vary under different culture temperatures and is strain dependent as well [37]. Likewise, physiological analysis of the effect of various carbon sources on enzyme activity is also important.…”

“…As indicated in [37], the maximum production of b-glucosidase would be supported by a suitable growth temperature and inoculum size. Hence, the interactive effects of temperature and inoculum size, AC, on the activity of b-glucosidase were evaluated, while the percentage of carbon sources and pH were maintained at their central values of 10% (w/v) and pH 7, respectively ( Figure 3).…”

“…The particularly low b-glucosidase activity at low pH levels was likely brought about by the extreme low pH values that dramatically shifted the pH transition region for the unfolding of the b-glucosidase system [37]. Since conditions of elevated pH and temperature have been thought to improve b-glucosidase activity [47], the relatively moderate optimum growth temperature and pH that produced high b-glucosidase activity in the broth cultures of T. harzianum seen in this study were unlike those previously reported.…”

Insights into structure ofPenicillium funiculosumLPMO and its synergistic saccharification performance with CBH1 on high substrate loading upon simultaneous overexpression

“…They are vital for cellulose degradation by catalyzing the hydrolysis of β-1,4 glycosidic bonds in cellulosic materials, to produce short cellulo-oligosaccharides and glucose (4). These enzymes from filamentous fungi perform a central role in the global carbon cycle by degrading insoluble cellulose to soluble sugars (5–7). Over time, the secretomes of many fungal genera such as Trichoderma, Aspergillus, Neurospora and Penicillium have been studied for their ability to produce cellulolytic enzymes.…”