Statistical optimization of one-step immobilization process for recombinant endoglucanase from Clostridium thermocellum

• Fuse endoglucanase CelA with plant-oil protein Oleosin (Ole-CelA).
• Assemble artificial oil bodies (AOBs) using oil and Ole-CelA to display CelA.
• Statistically optimize one-step refolding and immobilization of CelA on AOBs.
• Statistically optimize the reaction condition for CelA-bound AOBs.
• Stably recycle CelA-bound AOBs for reaction.

Endoglucanase CelA from Clostridium thermocellum (CtCelA) is a thermophilic endo-β-1,4-glucanase and has a low solubility when expressed in Escherichia coli. To make industrial application of CtCeA more appealing, artificial oil bodies (AOBs) was implemented for one-step renaturation and immobilization of recombinant CtCelA. CtCelA was first fused with oleosin (Ole-CtCelA), a structural protein of plant seed oils. Ole-CtCelA was overexpressed in E. coli, and its insoluble form was recovered and mixed with plant oils to assemble AOBs. Moreover, the Box–Behnken design and the central composite design were employed to optimize the condition for assembly of AOBs and the enzymatic reaction condition, respectively. Consequently, the approach led to the resumption of active CtCelA on AOBs. CtCelA-bound AOBs exhibited an optimum activity at 69 °C and pH 6.3 while the immobilized protein remained stable for several hours at 70 °C and after 5 repeated uses. Overall, it indicates a promise of this novel approach for direct processing and immobilization of recombinant CtCelA.