Enhancing the ethanol production by exploiting a novel metagenomic-derived bifunctional xylanase/β-glucosidase enzyme with improved β-glucosidase activity by a nanocellulose carrier

Abstract

Some enzymes can catalyze more than one chemical conversion for which they are physiologically specialized. This secondary function, which is called underground, promiscuous, metabolism, or cross activity, is recognized as a valuable feature and has received much attention for developing new catalytic functions in industrial applications. In this study, a novel bifunctional xylanase/β-glucosidase metagenomic-derived enzyme, PersiBGLXyn1, with underground β-glucosidase activity was mined by in-silico screening. Then, the corresponding gene was cloned, expressed and purified. The PersiBGLXyn1 improved the degradation efficiency of organic solvent pretreated coffee residue waste (CRW), and subsequently the production of bioethanol during a separate enzymatic hydrolysis and fermentation (SHF) process. After characterization, the enzyme was immobilized on a nanocellulose (NC) carrier generated from sugar beet pulp (SBP), which remarkably improved the underground activity of the enzyme up to four-fold at 80°C and up to two-fold at pH 4.0 compared to the free one. The immobilized PersiBGLXyn1 demonstrated 12 to 13-fold rise in half-life at 70 and 80°C for its underground activity. The amount of reducing sugar produced from enzymatic saccharification of the CRW was also enhanced from 12.97 g/l to 19.69 g/l by immobilization of the enzyme. Bioethanol production was 29.31 g/l for free enzyme after 72 h fermentation, while the immobilized PersiBGLXyn1 showed 51.47 g/l production titre. Overall, this study presented a cost-effective in-silico metagenomic approach to identify novel bifunctional xylanase/β-glucosidase enzyme with underground β-glucosidase activity. It also demonstrated the improved efficacy of the underground activities of the bifunctional enzyme as a promising alternative for fermentable sugars production and subsequent value-added products.

Enzyme technology in bioethanol production from lignocellulosic biomass: Recent trends with a focus on immobilized enzymes

“…As in the previous work, better results were achieved with coffee residue waste (Ariaeenejad et al 2021). The amount of reducing sugar produced from enzymatic saccharification enhanced from 15.9 g/L (Ariaeenejad et al 2021) to 19.7 g/L (Ariaeenejad et al 2023) and reached a bioethanol concentration of 51.5 g/L after 72 h fermentation, while 29.3 g/L for the soluble enzyme. The bifunctional biocatalyst reached 53.2% of retained xylanase and 39.3% of its β-glucosidase activity after 8 cycles.…”

“…More recently, the same group published a new study to identify a bifunctional enzyme with better β-glucosidase activity (Ariaeenejad et al 2023). This specific enzyme is responsible for hydrolyzing the oligomeric molecules, generating glucose (Allardyce et al 2010).…”

Characterization of a thermophilic and glucose-tolerant GH1 β-glucosidase from hot springs and its prospective application in corn stover degradation

“…D1 to exhibit β-galactosidase activity, thus rendering it a multifunctional enzyme. Akin findings are echoed by Ariaeenejad et al (2023) , who unveiled a novel recombinant bifunctional enzyme (xylanase/β-glucosidase), PersiBGLXyn1, within the human bovine rumen metagenome. These observations accentuate the enhanced utility of such bifunctional enzymes ( Bao et al, 2012 ; Ariaeenejad et al, 2021 ).…”

A refined picture of the native amine dehydrogenase family revealed by extensive biodiversity screening

“…Given access to the DNA of an entire microbiome, it is now possible to explore the biocatalytic potential of the global proteome. Many examples of metagenome-based enzymes have now been described for industrial applications, such as ligninases and xylanases for bioethanol 12 . In reality, many obstacles still have to be overcome to take full advantage of this type of resource for application.…”