Whole-cell immobilization using cell surface-exposed cellulose-binding domain

Specific adhesion of Eshcherichia coli with surface-exposed cellulose-bindi ng domain (CBD) to cellulosic materials was investigated. Whole-cell immobi lization was very specific, forming essentially a monolayer of cells onto t he different supports. Cells with surface-exposed CBD bound specifically an d tightly to cellulose supports at a wide range of pH. In contrast to CBD, which shows the highest binding to cellulose at 4 degreesC, highest cell lo ading was observed at 37 degreesC. The extent of immobilization was depende nt on the amount of surface-exposed CBD. Cells binding increased with incre asing amount of CBD until binding was saturated. Even induction of very low level of CBD (0.05 mM IPTG) was sufficient to provide specific and tight b inding to cellulose support. Because optimal binding can be obtained under physiological conditions such as pH 7 and 37 degreesC, the results demonstr ate the general utility of surface-exposed CBD as an efficient means of who le-cell immobilization.