CELLULOSE BEAD ENTRAPPED MICROBIAL-CELLS FOR BIOTECHNICAL APPLICATIONS

Immobilization of intact or pretreated microbial cells instead of partially purified enzymes offers several advantages. A novel method has been applied to entrap Actinoplanes missouriensis, Bacillus coagulans, Kluyveromyces fragilis, K. lactis, Saccharomyces cerevisiae, Serratia sp., and Streptomyces albus cells within α-cellulose beads, with activity recoveries of about 22 to 85%. The best results were obtained with S. albus for glucose isomerase and with S. cerevisiae for invertase. The application of entrapped glucose isomerase-active A. missouriensis cells to increase the sweetness of β-galactosidase-hydrolysed dairy products was investigated in detail. Pressure drop across the column reactor bed was negligible; the stability of the entrapped enzyme was highest at pH 7.5 in the presence of both Mg2+ and Co2+, although Co2+ could be omitted with little effect on performance; and the activity was drastically affected by Ca2+ content of substrate due to competition with Mg2+. The reactor was successfully operated for more than 5 weeks for the isomerization of demineralized concentrated whey hydrolysate of 8% lactose, 23% galactose, and up to 36% added glucose to obtain a syrup of sweetness approaching that of sucrose. © 1979.