Enhanced catalytic efficiency of Bacillus amyloliquefaciens SS35 endoglucanase by ultraviolet directed evolution and mutation analysis

Shweta Singh, Arun Dhillon and Arun Goyal

Renewable Energy, 2020, vol. 151, issue C, 1124-1133

Abstract: Bacillus amyloliquefaciens SS35 was subjected to ultraviolet irradiation to improve the enzymatic hydrolysis of lignocellulosic biomass. The resulting mutant, UV2, produced endoglucanase, carboxymethyl cellulase, CMCase-UV2 with 1.6–4.1-fold higher activity against cellulosic substrates than the wild type, CMCase-WT. CMCase-UV2 exhibited wider pH stability in the acidic range than CMCase-WT. The TLC analysis showed that the hydrolysis of CMC-Na and β-glucan by CMCase-UV2 produced glucose along with cello-oligosaccharides and cellobiose in 45 min, whereas, CMCase-WT produced, only cello-oligosaccharides and cellobiose in 120 min by endolytic mode of action. The hydrolysis of pretreated Pennisetum purpureum by CMCase-UV2 gave total reducing sugar yield 154.2 mg/g pretreated biomass in 48 h, which was 1.8-fold higher than CMCase-WT. CMCase-UV2 was the promising endoglucanase which improves the saccharification of lignocellulosic biomass therefore, it will improve the efficiency of the process, lignocellulose-based biorefineries for bioethanol production. The gene encoding cellulase was amplified from wild-type and UV2 strains using degenerate primers designed from phylogenetically related spp. Bacillus amyloliquefaciens KHG19 for family 5 glycoside hydrolase. Sequences analysis of genes from wild-type and UV2 strains showed the mutation, D233G. These results will provide information for protein engineering in designing mutant of endoglucanase for improved catalytic efficiency and pH stability.

Keywords: Carboxymethylcellulase; Ultraviolet directed evolution; Catalytic efficiency; pH tolerance; Saccharification; Point mutation (search for similar items in EconPapers)
Date: 2020
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Persistent link: https://EconPapers.repec.org/RePEc:eee:renene:v:151:y:2020:i:c:p:1124-1133

DOI: 10.1016/j.renene.2019.11.105

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