Abstract
Endoglucanase B (EGLB) derived from Aspergillus niger BCRC31494 has been used in the food fermentation industry because of its thermal and alkaline tolerance. It was cloned and expressed in Pichia pastoris. According to sequence analysis, the gene open reading frame comprises 1,217 bp with five introns (GenBank GQ292753). According to sequence and protein domain analyses, EGLB was assigned to glycosyl hydrolase family 5 of the cellulase superfamily. Several binding sites were found in the promoter region. The purified recombinant enzyme was induced by 0.5% methanol, and it exhibited optimal activity at 70 °C and pH 4. EGLB was stable for 3 h at temperatures below 60 °C, with more than 90% of its activity remaining. The enzyme was specific for substrates with β-1,3 and β-1,4 linkages. In Lineweaver-Burk plot analysis, the Km and Vmax values of EGLB for β-D-glucan were 134 mg/mL and 4.68 U/min/mg, respectively. The enzyme activity was increased by 1.86-fold by Co2+ and by 2-fold by Triton X-100 and Tween 80. These favorable properties make EGLB a potential candidate for use in laundry and textile industrial applications.
Highlights
IntroductionA polymer of glucose with β-1,4 linkages, is the most abundant biomass on Earth
Cellulose, a polymer of glucose with β-1,4 linkages, is the most abundant biomass on Earth
Exoglucanases catalyze the hydrolysis of crystalline cellulose from the ends of the cellulose chain to produce cellobiose, which is hydrolyzed to glucose by β-glucosidases [7,8]
Summary
A polymer of glucose with β-1,4 linkages, is the most abundant biomass on Earth. Aspergillus niger is the most important cellulase source for the fermentation of Asian foods [14] This fungus can secrete large amounts of different cellulases, and it is recognized as one of the more efficient cellulose-degrading microorganisms. Three endoglucanase genes, eglA, eglB, and eglC, had been found in A. niger. The molecular weight of eglA and eglB were 30 to 55 kDa and the two enzymes have high specificity toward beta-glucan Both two genes lack a cellulose-binding domain (CBD) and the associated linker region. A transcriptional activator XlnR regulates the transcription of the xlnB, xlnC, and xlnD genes encoding the main xylanolytic enzymes (endoxylanases B and C and β-xylosidase, respectively) [16]. The XlnR activates transcription of three endoglucanase-encoding genes, eglA, eglB, and eglC, indicating that transcriptional regulation by. In this study, through nested PCR and function-driven screening, the endoglucanase gene eglBwas identified using the genomic DNA of A. niger. eglB was expressed in Picha pastoris, and the recombinant enzyme was purified to characterize its properties
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
