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Biotechnology and Applied Biochemistry (2003) 38, (43–51) (Printed in Great Britain)

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A strategic study using mutant-strain entrapment in calcium alginate for the production of Saccharomyces cerevisiae cells with high invertase activity

Juan Carlos Rossi-Alva*¹ and Maria Helena Miguez Rocha-Leão†

*Departamento de Bioquímica, Instituto de Química, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21910-21900, Brazil, and †Departamento de Engenharia Bioquímica, Escola de Química, Universidade Federal do Rio de Janeiro, 21910.900, Rio de Janeiro, Brazil

Key words: calcium alginate, cell entrapment, invertase, sucrose hydrolysis, yeast.

Abbreviations used: F cells, free cells; E cells, entrapped cells; EGM cells, entrapped cells previously grown inside the matrix; PFK, phosphofructokinase.

¹To whom correspondence should be addressed (e-mail jcrossi@iq.ufrj.br).

Entrapped cells and entrapped cells grown inside of a calcium alginate matrix as well as free cells have been investigated using Saccharomyces cerevisiae mutant strains with regard to their pattern of growth and invertase activity. The repression of invertase by glucose and glucose-consumption ability were considered in the selection process of the mutants. Efficient sucrose bioconversion due to high invertase activity was obtained when entrapped mutant strain Q6R2 cells were grown within calcium alginate gel beads using sucrose plus glucose as the carbon source. Under these conditions, 1 mg (dry weight) of entrapped cells is able to produce 20 mmol of inverted sugar in 3 min (the maximum activity obtained was 20 units·mg^-1). The experiments were carried out for 6 months without appreciable loss of either bead integrity or invertase activity. The biocatalyst was also stored at 4 °C for 6 months without appreciable loss of the invertase activity. This work shows that entrapped yeast cells with a weak ability to consume sugar may be used to produce inverted sugar.

Received 24 October 2002/6 February 2003; accepted 27 February 2003

Published as Immediate Publication 27 February 2003, DOI 10.1042/BA20020101

© 2003 Portland Press Ltd