Enhanced accumulation of toxic compound in yeast cells having high glycolytic activity: a case study on the safety of genetically engineered yeast


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The cellular level of methylglyoxal (MG), a highly toxic 2-oxoaldehyde, in Saccharomyces cerevisiae cells transformed with genes for some of the glycolytic enzymes was determined as an index of the safety of genetically engineered yeast and the level was compared with that in non-transformed control cells. the phosphoglucose isomerase (PGI), phosphofructokinase (PFK) and triosephosphate isomerase (TPI) activities significantly increased in the transformants and were approximately five-, three- and sevenfold higher, respectively, than those in the control. When these transformed cells were used for alcohol fermentation from glucose, they accumulated MG in cells at a level sufficient to induce mutagenicity. These results illustrate that careful thought should be given to the potential metabolic products and their safety when a genetically engineered yeast is applied to food-related fermentation processes.