Optimization of the concentrations of agar, chitosan and sodium polyphosphate for the immobilization of yeast (Saccharomyces cerevisiae) in carboxymethyl-nata

Date

4-2010

Degree

Bachelor of Science in Chemistry

Adviser/Committee Chair

Veronica C. Sabularse

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Abstract

Carboxymethyl-nata was synthesized from nata de coco. The preparation involved pretreatment using isopropyl alcohol, mercerization, and etherification. The physico-chemical properties of derived CMN were determined. The moisture content, degree of substitution, molecular weight, and degree of polymerization were 4.16%, 0.22, 425 KDa, and 2.62 x 103, respectively. The percent solubles in water was 15.92%. The derivatization of CMN from nata cellulose was confirmed by infrared spectroscopy. Yeast cells were immobilized in beads composed of CMN, agar, chitosan, and sodium polyphosphate. The optimum agar, chitosan, and sodium polyphosphate concentration for bead formation and immobilization were 2%, 1%, and 1%, respectively. The Km for the immobilized cells was 0.050 M and the Vmax was 7.53 μmole/min. The free yeast cells had a Km of 0.064 M and a Vmax of 7.69. The Km values indicated the greater affinity of immobilized cells for sucrose. The immobilized yeast cells exhibited maximal activity at a pH of 4.5, a temperature of 65oC, and a sucrose concentration of 0.3 M. The free yeast cells, however, showed maximal activity at a relatively lower pH of 4.0, and a lower temperature of 60oC. The optimum sucrose concentration of the free yeast cells was also at 0.3 M. The immobilized yeast cells were relatively stable toward repeated use. After five days of repeated use the activity of the immobilized yeast cells was 11% more than the initial activity.

Language

English

Call Number

LG 993.5 2010 C42 D53

Document Type

Thesis

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