Alterations of the glucose metabolism in a triose phosphate isomerase‐negative Saccharomyces cerevisiae mutant

Abstract

The absence of triose phosphate isomerase activity causes an accumulation of only one of the two trioses, dihydroxyacetone phosphate, and this produces a shift in the final product of glucose catabolism from ethanol to glycerol (Compagno et al., 1996). Alterations of glucose metabolism imposed by the deletion of the TPI1 gene in Saccharomyces cerevisiae were studied in batch and continuous cultures. The Dtpi1 null mutant was unable to grow on glucose as the sole carbon source. The addition of ethanol or acetate in media containing glucose, but also raffinose or galactose, relieved this effect in batch cultivation, suggesting that the Crabtree effect is not the primary cause for the mutant's impaired growth on glucose. The addition of an energy source like formic acid restored glucose utilization, suggesting that a NADH/energy shortage in the Dtpi1 mutant could be a cause of the impaired growth on glucose. The amount of glycerol production in the Dtpi1 mutant could represent a good indicator of the fraction of carbon source channelled through glycolysis. Data obtained in continuous cultures on mixed substrates indicated that different contributions of glycolysis and gluconeogenesis, as well as of the HMP pathway, to glucose utilization by the Dtpi1 mutant may occur in relation to the fraction of ethanol present in the media.

Saccharomyces cerevisiae KNU5377 Stress Response during High-Temperature Ethanol Fermentation

“…Gpd1 (Tdh1) and Gpd2 (Tdh2) convert DHAP to glycerol-3-phosphate (G3P). High Gpd activity maintains the cytosolic redox balance during batch growth on ethanol-containing medium (Compagno et al, 2001). Accordingly, high Gpd (GAPDH or Tdh) expression was observed in KNU5377 during batch fermentation (Figs.…”

“…Reduced Tpi1p activity causes an accumulation of dihydroxyacetone phosphate (DHAP). Increased DHAP alters cell metabolism by depleting ATP and trapping inorganic phosphate, forming a toxic methylglyoxal (MG) by non-enzymatic/ enzymatic conversion of DHAP, leading to stress sensitivity (Compagno et al, 2001). The most remarkable effect in tpi1 mutant cells is that the final product of glucose catabolism is glycerol instead of ethanol.…”

Phylogenetic Selection Guided Saccharomyces Cerevisiae S288c Glucose Fermentation Modeling

“…Figure 2 shows the phylogeny of GLK1 gene to cluster the genes similar to GLK1 for tracing the closest genetic copy [ Homozygous diploid GPM1 mutant studied [21] failed to sporulate [24], which proved that gluconeogenesis was required for sporulation [16] ADH3 reduce acetaldehyde to ethanol [27] during glucose fermentation. ADH4 was purified later to study its activity [28].…”

Metabolic Engineering of Glycerol Production inSaccharomyces cerevisiae

“…Glucose repression of the synthesis of key enzymes of respiratory glucose dissimilation (16,50) may therefore prevent growth of tpi1⌬ mutants on glucose in batch cultures. However, tpi1⌬ mutants also failed to grow in aerobic, glucose-limited chemostat cultures, in which glucose repression is alleviated (11). As in batch cultures, growth on glucose in chemostat cultures required the inclusion of ethanol in the medium feed (11).…”

“…However, tpi1⌬ mutants also failed to grow in aerobic, glucose-limited chemostat cultures, in which glucose repression is alleviated (11). As in batch cultures, growth on glucose in chemostat cultures required the inclusion of ethanol in the medium feed (11). This indicated that glucose repression of respiration is not the only factor that prevents growth of tpi1⌬ mutants on glucose as the sole carbon source.…”