Enhanced fermentative capacity of yeasts engineered in storage carbohydrate metabolism

Abstract

During yeast biomass production, cells are grown through several batch and fed-batch cultures on molasses. This industrial process produces several types of stresses along the process, including thermic, osmotic, starvation, and oxidative stress. It has been shown that Saccharomyces cerevisiae strains with enhanced stress resistance present enhanced fermentative capacity of yeast biomass produced. On the other hand, storage carbohydrates have been related to several types of stress resistance in S. cerevisiae. Here we have engineered industrial strains in storage carbohydrate metabolism by overexpressing the GSY2 gene, that encodes the glycogen synthase enzyme, and deleting NTH1 gene, that encodes the neutral trehalase enzyme. Industrial biomass production process simulations were performed with control and modified strains to measure cellular carbohydrates and fermentation capacity of the produced biomass. These modifications increased glycogen and trehalose levels respectively during bench-top trials of industrial biomass propagation. We finally show that these strains display an improved fermentative capacity than its parental strain after biomass production. Modification of storage carbohydrate content increases fermentation or metabolic capacity of yeast which can be an interesting application for the food industry.

MAL62 Overexpression Enhances Freezing Tolerance of Baker’s Yeast in Lean Dough by Enhancing Tps1 Activity and Maltose Metabolism

“…That may be because neutral trehalase could be encoded by multiple genes, such as the NTH2 gene. , However, NTH1 deletion can still help slow down the trehalose degradation in B – NTH1, B – N + T, B – N + T + K, B – N + M, and B – N + T + MAL62 strains. This explains why the tripartite mutant (B – N + T + MAL62) provides the best enhancement for the freezing tolerance and improves the fermentation characteristics …”

MAL62 overexpression and NTH1 deletion enhance the freezing tolerance and fermentation capacity of the baker’s yeast in lean dough

“…In addition, we found that NHT1 deletion (B-NTH1, B-NTH1 + K and B-NTH1 + MAL62) induced a low neutral trehalase (Table 3 ), which caused a lower level of trehalose degradation. High activity of trehalose synthase (+MAL62) [ 38 ] and low activity of neutral trehalase (−NTH1) increase the intracellular trehalose level [ 26 ], which explains why the double mutant (B-NTH1 + MAL62) provides the best freezing tolerance and fermentation characteristics [ 39 ].…”

Genetically Modified Yeasts in Wine Biotechnology

“…Overexpression of TPS1 (synthase subunit of trehalase-6-P synthase/phosphatase complex) and deletion of NTH1 (neutral trehalose) increase ethanol tolerance [17]. Besides, overexpression of GSY2 (Glycogen synthase) and NTH1 increased respectively glycogen and trehalose levels that are important for the fermentative capacity [18]. Global transcription machinery engineering (gTME) is a technique that alter key proteins to regulate the global transcriptome by error-prone polymerase chain reaction (epPCR) mutations.…”