Surface plasmon resonance imaging of the enzymatic degradation of cellulose microfibrils

We present the first study of the interaction of a cellulase enzyme mixture with cellulose microfibrils using surface plasmon resonance (SPR) imaging. The cellulose microfibrils, obtained from the bacterium Acetobacter xylinum, were heterogeneously distributed on a thin layer of thioglucose deposited onto a gold film. SPR images collected as a function of time allowed us to observe the adsorption of the enzymes onto both the cellulose microfibrils and the bare surface, and the subsequent degradation of the cellulose microfibrils in real time. In particular, we were able to characterize the decrease in the thickness and variations in thickness of the cellulose microfibril-coated regions with time, and to define a characteristic time for the removal of cellulose from the surface. These results demonstrate the distinct advantage of the SPR imaging technique for measuring the effectiveness of enzymes on cellulose microfibrils and provide useful metrics of enzyme activity that are of relevance to the cellulosic ethanol industry.