Fig. 4

Surface display and activity assessment of different IsPETase variants. a Activity of wt, Austin, and Son IsPETase variants expressed via the LppOmpA surface display module prior to and post TEV cleavage, hence release from the cell surface. To allow comparison of absorbance, values are relative to IsPETase^WT activity prior to TEV cleavage. Expression of all samples was performed at 16 °C. b Whole-cell fluorescence verification of surface-displayed IsPETase variants (wt, Austin, Son) prior to TEV cleavage. c Activity of IsPETase^WT and IsPETase^Son on pNP-acetate after His-tag purification. Buffer blank: 50 mM HEPES buffer. d Activity and detection of the previously described IsPETase variants expressed on the surface and subsequently cleaved off (TEV supernatant) and His-tag purified (purified). Activity of the released IsPETase variants on PET microparticles (upper half) and detection of the His-tagged enzymes via western blot (lower half) using an anti-His antibody. NC: Negative control BL21(DE3) cells