ISSN:
1432-0614
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Process Engineering, Biotechnology, Nutrition Technology
Notes:
Summary The cellular β-galactosidase activities produced by thelac'Z gene ofEscherichia coli, cloned on YEp, YRp, or YCp-type plasmids in host cells ofSaccharomyces cerevisiae with different ploidies, and which was expressed by a modified jeastHIS5 promoter, showed characteristic differences depending on the plasmid. But for any given plasmid, the isogenic diploid and tetraploid transformants showed slightly lower enzyme activities than their respective haploid transformants. This was due to the similar copy numbers of the plasmids in host cells. Since the cell number per unit volume of the culture decreased with increasing cell ploidy, the enzyme activity per unit volume of the culture decreased significantly. The holding stability of plasmids increased with increasing ploidy of the host cell, especially that of the YRp plasmid. On the YRp plasmid, thelac'Z gene showed higher productivity withTRP1 thanLEU2 as the selection marker for the plasmid.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00938964
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