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

Specific adhesion of Eshcherichia coli with surface-exposed cellulose-binding domain (CBD) to cellulosic materials was investigated. Whole-cell immobilization was very specific, forming essentially a monolayer of cells onto the different supports. Cells with surface-exposed CBD bound specifically and tightly to cellulose supports at a wide range of pH. In contrast to CBD, which shows the highest binding to cellulose at 4 degrees C, highest cell loading was observed at 37 degrees C. The extent of immobilization was dependent on the amount of surface-exposed CBD. Cells binding increased with increasing 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 binding to cellulose support. Because optimal binding can be obtained under physiological conditions such as pH 7 and 37 degrees C, the results demonstrate the general utility of surface-exposed CBD as an efficient means of whole-cell immobilization.