Abstract
Cellulose is the cheapest, natural, renewable organic substance that is used as a carbon source in various fields. Water hyacinth, an aquatic plant rich in cellulose, is often used as a raw material in fuel production. However, natural cellulase can be hardly used in industrial production on account of its low thermal stability and activity. In this study, a metagenomic library was constructed. Then, a new cellulase gene, cel1029, was screened by Congo red staining and expressed in the prokaryotic system. Enzymatic properties of Cel1029 were explored, including optimum temperature and pH, thermal and pH stability, and tolerance against organic solvents, metal ions, and salt solutions. Finally, its ability of degrading water hyacinth was identified and evaluated. Cel1029 displayed high homology with endoglucanase in the glycoside hydrolase family 5 (GH5) and had high stability across a broad temperature range. More than 86% of its enzymatic activities were retained between 4 and 60 °C after 24 h of incubation. Single-factor analysis and orthogonal design were further conducted to determine the optimal conditions for the highest reducing sugar yield of water hyacinth. Interestingly, Cel1029 efficiently transformed water hyacinth with a reducing sugar yield of 430.39 mg/g in 22 h. These findings may open the door for significant industrial applications of a novel GH5 cellulase (NCBI Reference Sequence: MK051001, Cel1029) and help identify more efficient methods to degrade cellulose-rich plants.
Highlights
Cellulase, including endoglucanase, exoglucanase and glucosidase (1,4-D-glueosidase, EC3.2.1.21), is a type of enzymes that can hydrolyze the β-1,4-glycosidic bond between cellulose molecules (Lin et al 2016)
Cellulase is distributed in many families, and the endoglucanases belonging to the glycoside hydrolase family 5 (GH5) have high similarity in both amino acid sequence and two strict conserved catalytic residues of glutamic acid (Yuan et al 2019; Matsuyama et al 1999)
We screened 7, 200 positive clones from a metagenomic library, which was built by extracting the total DNA from soil microbes
Summary
Cellulase, including endoglucanase (endo-1,4-D-glueanase, EC3.2.1.4), exoglucanase (exo-1,4-Dglucanase, EC3.2.1.91) and glucosidase (1,4-D-glueosidase, EC3.2.1.21), is a type of enzymes that can hydrolyze the β-1,4-glycosidic bond between cellulose molecules (Lin et al 2016). Endocellulase mainly catalyzes degradation of the amorphous region in cellulose, providing the starting site for further catalysis of exocellulase, so it plays an important role in efficient degradation of cellulose. The two residues are considered as catalytic proton donors and active site nucleophiles, respectively. They can maintain the structure of the substrate isocarbon of the enzyme (Valérie et al 1995). Various cellulase has been isolated from bacteria, fungi (Okada 1976), plants and higher animals, thermostable cellulase with excellent properties still needs to be discovered (Morteza et al 2020; Zheng et al 2018)
Sign-in/Register to view highlights & summary 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 callMore From: International microbiology : the official journal of the Spanish Society for Microbiology
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
