Expression of xylanase on Escherichia coli using a truncated ice nucleation protein of Erwinia ananas (InaA)

Abstract

Cell surface display involves the anchoring of enzymes on the surface of cells to be used as whole-cell biocatalysts. In this study, an ice nucleation protein (INP) anchor from Erwinia ananas IN-10, InaA, was used to display xylanase. The ability of InaA to be targeted to the outer membrane was compared to cells displaying xylanase using two other INPs, InaK and InaZ. SDS-PAGE and western blot of the outer membrane fraction proved that surface targeting was successful. Whole-cell xylanase activity showed that InaA anchored xylanase gave an activity of 92.2 U/g dry cell weight which was up to three times higher than the other two display constructs used. Surface anchoring of InaA was up to four times better compared to the other two INP anchors as was confirmed by flow cytometry. Expression of InaA on the surface was optimized by one-factor-at-a-time (OFAT) to obtain the optimum parameter conditions for highest surface expression. The results presented showed that InaA is an excellent INP for surface display for xylanase and has great potential in the degradation of xylan.