Fig. 4

Time-lapse AFM topography and recognition images of an isolated pretreated crystalline cellulose hydrolyzed by CBH I and β-G. Topography images (a–e, k–o) and recognition images (f–j, p–t) show the cellulose structure before enzyme hydrolysis and at 15, 45, 135, 170, 220, 250, 295, 340, 465 min after addition of CBH I and β-G. The cross section analysis along the green lines is presented under each image. The cellulose is divided into three regions and labeled them as A, B, and C in (b). Peaks generated from the cellulose peeling action on each region are marked using solid red circle, blue diamond and yellow circle in the cross section profiles, separately. All images were taken in 400 × 400 nm scan size. u Schematic presentation of possible hydrolysis mechanism of pretreated cell wall on the presence of CBH I