Abstract
A flocculent Saccharomyces cerevisiae strain secreting Aspergillus niger β-galactosidase activity was constructed by transforming S. cerevisiae NCYC869-A3 strain with plasmid pVK1.1 harboring the A. niger β-galactosidase gene, lacA, under the control of the ADH1 promoter and terminator. Compared to other recombinant S. cerevisiae strains, this recombinant yeast has higher levels of extracellular β-galactosidase activity. In shake-flask cultures, the β-galactosidase activity detected in the supernatant was 20 times higher than that obtained with previously constructed strains (Domingues et al. 2000a). In bioreactor culture, with cheese-whey permeate as substrate, a yield of 878.0 nkat/gsubstrate was obtained. The recombinant strain is an attractive alternative to other fungal β-galactosidase production systems as the enzyme is produced in a rather pure form. Moreover, the use of flocculating yeast cells allows for enzyme production with high productivity in continuous fermentation systems with facilitated downstream processing.
Original language | English |
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Pages (from-to) | 645-650 |
Journal | Applied Microbiology and Biotechnology |
Volume | 58 |
Issue number | 5 |
DOIs | |
Publication status | Published - 22 Apr 2002 |
MoE publication type | A1 Journal article-refereed |
Funding
Acknowledgements The authors acknowledge the financial support provided by the Instituto de Biotecnologia e Química Fina (IBQF), Portugal. Lucília Domingues was supported by a grant (PRAXIS XXI/BD/11306/97) from Fundação para a Ciência e Tecnologia, Portugal.
Keywords
- Fermentation
- Saccharomyces cerevisiae
- Aspergillus niger
- Recombinant strain
- continuous fermentation