This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Gasent-Ramirez, J. M. Articles by Benitez, T. Search for Related Content PubMed PubMed Citation Articles by Gasent-Ramirez, J. M. Articles by Benitez, T. Agricola Articles by Gasent-Ramirez, J. M. Articles by Benitez, T.

 Previous Article  |  Next Article 

Appl. Environ. Microbiol., Dec 1997, 4800-4806, Vol 63, No. 12
Copyright © 1997, American Society for Microbiology

Lysine-overproducing mutants of Saccharomyces cerevisiae baker's yeast isolated in continuous culture

JM Gasent-Ramirez and T Benitez
Department of Genetics, University of Seville, Spain.

Saccharomyces cerevisiae baker's yeast mutants which produce 3 to 17 times as much lysine as the wild type, depending on the nitrogen source, have been selected. The baker's yeast strain was growth in a pH- regulated chemostat in minimal medium with proline as the nitrogen source, supplemented with increasing concentrations of the toxic analog of the lysine S-2-aminoethyl-L-cysteine (AEC). The lysine-overproducing mutants, which were isolated as AEC-resistant mutants, were also resistant to high external concentrations of lysine and to alpha- aminoadipate and seemed to be affected in the lysine biosynthetic pathway but not in the biosynthetic pathways of other amino acids. Lysine overproduction by one of the mutants seemed to be due to, at least, the loss of repression of the homocitrate synthase encoded by the LYS20 gene. The mutant grew slower than the wild type, and its dough-raising capacity was reduced in in vitro assays, probably due to the toxic effects of lysine accumulation or of an intermediate produced in the pathway. This mutant can be added as a food supplement to enrich the nutritive qualities of bakery products, and its resistance to alpha- aminoadipate, AEC, and lysine can be used as a dominant marker.

This article has been cited by other articles:

• Arensdorf, J. J., Loomis, A. K., DiGrazia, P. M., Monticello, D. J., Pienkos, P. T. (2002). Chemostat Approach for the Directed Evolution of Biodesulfurization Gain-of-Function Mutants. Appl. Environ. Microbiol. 68: 691-698 [Abstract] [Full Text]  
• Rincon, A. M., Codon, A. C., Castrejon, F., Benitez, T. (2001). Improved Properties of Baker's Yeast Mutants Resistant to 2-Deoxy-D-Glucose. Appl. Environ. Microbiol. 67: 4279-4285 [Abstract] [Full Text]