Dictyoglomus turgidum is a hyperthermophilic, anaerobic, gram-negative bacterium that shows an array of putative glycoside hydrolases (GHs) encoded by its genome, a feature that makes this microorganism very interesting for biotechnological applications. The aim of this work is the characterization of a hyperthermophilic GH5, Dtur_0671, of D. turgidum, annotated as endoglucanase and herein named DturCelB in agreement to DturCelA, which was previously characterized. The synthetic gene was expressed in Escherichia coli. The purified recombinant enzyme is active as a monomer (40 kDa) and CD structural studies showed a conserved α/β structure at different temperatures (25 and 70 °C) and high thermoresistance (Tm of 88 °C). Interestingly, the enzyme showed high endo-β-1,4-mannanase activity vs various mannans, but low endo-β-1,4 glucanase activity towards carboxymethylcellulose. The KM and Vmax of DturCelB were determined for both glucomannan and CMC: they were 4.70 mg/ml and 473.1 μmol/min mg and 1.83 mg/ml and 1.349 μmol/min mg, respectively. Its optimal activity towards temperature and pH resulted to be 70 °C and pH 5.4, respectively. Further characterization highlighted good thermal stability (~ 50% of enzymatic activity after 2 h at 70 °C) and pH stability over a broad range (> 90% of activity after 1 h in buffer, ranging pH 5–9); resistance to chemicals was also observed.
CITATION STYLE
Fusco, F. A., Ronca, R., Fiorentino, G., Pedone, E., Contursi, P., Bartolucci, S., & Limauro, D. (2018). Biochemical characterization of a thermostable endomannanase/endoglucanase from Dictyoglomus turgidum. Extremophiles, 22(1), 131–140. https://doi.org/10.1007/s00792-017-0983-6
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