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An optimal blend of single autodisplayed cellulases for cellulose saccharification – a proof of concept

Obeng, Eugene Marfo, Ongkudon, Clarence M, Budiman, Cahyo, Maas, Ruth, Jose, Joachim
Journal of chemical technology and biotechnology 2018 v.93 no.9 pp. 2719-2728
beta-glucosidase, calcium chloride, cellulose, endo-1,4-beta-glucanase, hydrolysis, lignocellulose, mixing, pH, polysorbates, saccharification, screening, sugars, synergism, temperature
BACKGOUND: To date, it has been challenging to determine the optimal proportions of the individual cellulases in crude extracts and multienzyme systems to promote enzyme synergism. The application of single surface‐display of enzymes may obviate such challenges. This article presents a proof of concept of the optimal mixing of single surface‐displayed cellulases for cellulose hydrolysis using Simplex lattice mixture design. RESULTS: The recently discovered maximized autotransporter‐mediated expression system was used to express the three cellulases. The biochemical screening analysis revealed that the enzymes have a broad range of functional pH (4–9) and temperature (30–100 °C) characteristics. The evaluated optima were pH 6 and 60 °C. Through the statistical design of experiment, a blend ratio of 1: 1.6: 1.4 of endoglucanase: exoglucanase: β‐glucosidase was identified as the ‘sweet spot’ for optimum sugar yield. The application of this blend generated about 0.354 mg mL‐¹ and 0.446 mg mL‐¹ of sugars from filter paper (Ø 6 mm, ∼2.5 mg) and 2.5% pretreated EFB, respectively, within 12 h. Supplementing the enzyme blend with CaCl₂ and Tween 20 improved the sugar yield. CONCLUSION: This research has revealed an interesting concept of efficiently addressing cellulase synergism. The overall outcome of this research is promising for the derivation of value from lignocellulose. © 2018 Society of Chemical Industry