Immobilization of Saccharomyces cerevisiae in Gelatin Cross-Linked with Chromium Ions for Conversion of Sucrose by Intracellular Invertase

Abstract

A novel immobilized biocatalyst with invertase (β-D-fructofuranosidase, E.C.3.2.1.26) activity was prepared by immobilizing Saccharomyces cerevisiae cells into gelatin by using chromium salts. The effect of chromium salts on cell growth of free and immobilized cells was investigated, and optimum concentrations for chromium acetate and chromium sulfate were found to be 0.016 M and 0.008 M, respectively. Since a medium feeding strategy was applied, higher enzymatic activities were obtained with developed biocatalyst compared to free S. cerevisiae cells. Immobilized samples could be used 10 times in a 30-day period with negligible activity loss. After storing it at 25°C for 28 days, our biocatalyst was used 15 times with 2-day intervals with only a slight amount of activity decrease. As a result we managed to produce a very stable biocatalyst with high invertase activity using an inexpensive methodology.

Keywords:

• Cell immobilization
• Chromium salts
• Gelatin
• Invertase
• Saccharomyces cerevisiae
• Sucrose
• Yeast