Sol-Gel Entrapment of Escherichia coli

Whole cell bacteria have been entrapped within sol-gel silica matrices in order to perform bio-catalytic experiments. Escherichia coli have been chosen as a model for sol-gel encapsulation. Transmission electron microscopy shows that bacteria are randomly dispersed within the silica matrix and that their cellular organization is preserved. The -galactosidase activity of entrapped E. coli was studied using p-NPG as a substrate. The formation of p-nitrophenol was followed by optical absorption. These experiments show that E. coli still exhibit noticeable enzymatic activity after encapsulation in wet gels. They follow the well known Michaelis-Menten kinetic law but their activity decreases in dried xerogels.