A polyelectrolyte complex gel was prepared by mixing chitosan and K-carrageenan solutions in the presence of NaCl. To study the effect of ambient pH on the swelling behavior, the diameter of the cylindrical gel ( 4 mm X 8 mm) immersed in aqueous NaOH, KOH, or HC1 solution was measured. In the range of pH 10-12, the diameter increased with time, and the gel reached swelling equilibrium within 6 days. In an NaOH solution of pH 10.5, the maximum swelling occurred, and the volume of the gel at equilibrium was 10.2 times as large as the initial one. At pH below 9 and at pH 13, no swelling was observed. Thus, the swelling of the complex gel prepared in this study was sensitive to a rather narrow range of pH. The swelling equilibrium in the presence of NaCl was also investigated at various pH.

No abstract

No abstract

-ku, Tokyo, J a p a n SYNOPSIS Polyelectrolyte complex (PEC) 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 immobilizedcells 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.

No abstract