Fig. 5

Tracking xylanase hydrolysis of UBKP using OC15 probe. Paper discs were incubated with xylanase (0.4 U/paper disc and 0.1 U/paper disc) for up to 18 h (pH 6) at room temperature under continuous agitation (150 rpm). Untreated UBKP and xylanase-treated UBKP paper discs were incubated with OC15 probe (0.06 µg/µL) for 1 h at room temperature under agitation. Three percent (w/v) milk (20 mM Tris–HCl, pH 7.5 with 20 mM NaCl and 5 mM CaCl₂) was used to minimize paper auto-fluorescence and non-specific binding of the OC15 probe. The fluorescence values were converted to OC15 (µg/mm²) using a standard curve (Additional file 9)