Utilization of sol–gel ceramics for the immobilization of living microorganisms

Two possible methods are described for using sol–gel technology to immobilize living microorganisms, either embedding the cells within thin silica layers, or using the technique of freeze-gelation to immobilize microorganisms within molded ceramic parts. The preparation and structure of both biocer variants are outlined, and examples are given for the activity and storage stability of embedded microorganisms. Silica layers were used to immobilize various bacteria and algae. Survival rates after storage are given for Pseudomonas fluorescence bacteria and for green algae such as H. pluvialis, C. vulgaris, B. braunii and N. limnetica embedded within thin transparent silica layers. The bioactivity of bacteria immobilized in freeze-gelation ceramics was investigated by monitoring glucose consumption for P. fluorescens NCIMB 11764, and phenol degradation for Rhodococcus ruber.