Assessment of macroporous polystyrene-based polymers for the immobilization of Citrobacter freundii

POLYHIPE™ polymers represent a novel immobilization support possessing many desirable characteristics. These materials have been used to immobilize Citrobacter freundii in order to develop a continuous bioconversion system for the anaerobic production of trimethylene glycol from glycerol. Several immobilization methods were employed, of which the most successful involved culturing the organism with POLYHIPE in shake-flasks, transferring the contents into a column, and growing the cells in situ within the column. Cell activity was determined by the amount of TMG produced from a buffered glycerol solution. The latter was passed through the columns by either a recirculation system or the superior single-pass method. The optimal system was scaled up and showed potential for further large-scale investigations. Cell lifetime in the column could be improved by supplying the cells with diluted growth medium in place of the buffer.