Two promising alkaline β-glucosidases isolated by functional metagenomics from agricultural soil, including one showing high tolerance towards harsh detergents, oxidants and glucose. (1st March 2014)

• Record Type: Journal Article
• Authors: Biver, Sophie; Stroobants, Aurore; Portetelle, Daniel; Vandenbol, Micheline
• Is Part Of: Journal of industrial microbiology & biotechnology. Volume 41:Number 3(2014)
• Page Start: 479
• Page End: 488
• Publication Date: 2014-03-01
• Subjects: Alkaline enzyme -- β-Glucosidase -- Detergent -- Functional metagenomics -- Glucose tolerance; Industrial microbiology -- Periodicals; 660.62
• DOI: 10.1007/s10295-014-1400-0
• Languages: English
• ISSNs: 1367-5435

Abstract

Abstract: New β-glucosidase activities were identified by screening metagenomic libraries constructed with DNA isolated from the topsoil of a winter wheat field. Two of the corresponding proteins, displaying an unusual preference for alkaline conditions, were selected for purification by Ni-NTA chromatography. AS-Esc6, a 762-amino-acid enzyme belonging to glycoside hydrolase family 3, proved to be a mesophilic aryl-β-glucosidase with maximal activity around pH 8 and 40 °C. A similar pH optimum was found for AS-Esc10, a 475-amino-acid GH1-family enzyme, but this enzyme remained significantly active across a wider pH range and was also markedly more stable than AS-Esc6 at pH greater than 10. AS-Esc10 was found to degrade cellobiose and diverse aryl glycosides, with an optimal temperature of 60 °C and good stability up to 50 °C. Unlike AS-Esc6, which showed a classically low inhibitory constant for glucose (14 mM), AS-Esc10 showed enhanced activity in the presence of molar concentrations of glucose. AS-Esc10 was highly tolerant to hydrogen peroxide and also to sodium dodecyl sulfate, this being indicative of kinetic stability. This unique combination of properties makes AS-Esc10 a particularly promising candidate whose potential in biotechnological applications is worth exploring further.