Discovery of two novel β-glucosidases from an Amazon soil metagenomic library

Abstract An Amazon soil microbial community metagenomic fosmid library was functionally screened for β-glucosidase activity. Contig analysis of positive clones revealed the presence of two ORFs encoding novel β-glucosidases, AmBGL17 and AmBGL18, from the GH3 and GH1 families, respectively. Both AmBGL17 and AmBGL18 were functionally identified as β-glucosidases. The enzymatic activity of AmBGL17 was further characterized. AmBGL17 was tested with different substrates and showed highest activity on pNPβG substrate with an optimum temperature of 45 °C and an optimum pH of 6. AmBGL17 showed a Vmax of 116 mM s−1 and Km of 0.30 ± 0.017 mM. This is the first report of β-glucosidases from an Amazon soil microbial community using a metagenomic approach. Two novel beta-glucosidase enzymes were found through a functional screening of a metagenomic library constructed from total DNA isolation of Amazon soil. One of the enzymes was successfully purified and chemically characterized. This is the first report of β-glucosidase discovery using a metagenomic approach from an Amazon soil microbial community.