Application of polyelectrolyte complex gel composed of xanthan and chitosan to the immobilization of Corynebacterium glutamicum

Polyelectrolyte complex (PEG) gel prepared from xanthan and chitosan was applied to the immobilization of Corynebacterium glutamicum (IAM 12433) having fumarase activity. A C. glutamicum cells suspension was mixed with xanthan and chitosan solution in the presence of NaCl below room temperature. Thereafter, the mixture was rinsed in distilled water and the PEC immobilized cells were obtained. The fumarase activity of the immobilized cells or intact ones was estimated by the amount of malate produced. The fumarase activity of immobilized cells was about 5 times that of intact cells. It was suggested that the interaction between the polycation (chitosan) and the C. glutamicum cells contributed to the enhancement of fumarase activity. In the column experiment, the immobilized cells were stable in an electrolyte solution of high concentration; about 90% of the initial fumarase activity was retained for 240 h. In addition, the pore size distribution for the xanthan/chitosan gel was measured by a solute exclusion method. As the result, the pore size of the xanthan/chitosan gel was similar to that of polysaccharide gels. (C) 1996 John Wiley & Sons, Inc.