Multistep reactions with immobilized microorganisms.

This review presents some examples of new semicontinuous and continuous processes for product formation and for degradation of xenobiotics with immobilized microorganisms. A semicontinuous process for glycerol formation with Saccharomyces cerevisiae cells, adsorbed on sintered glass, and a continuous production of citric acid with Aspergillus niger, entrapped in calcium alginate, are given as examples of the production of primary metabolites. The production of ergot alkaloids with entrapped Claviceps purpurea demonstrates the possibilities of production of secondary metabolites. The continuous degradation of phenolic substances and that of 4-chlorophenol by entrapped and adsorbed microorganisms are given as examples of the possibility of a continuous degradation of xenobiotics by immobilized microorganisms. The continuous degradation of these substances was successful not only in artificial solutions but also in sterile and nonsterile wastewater.