Metabolic Engineering of Acetaldehyde Production by Streptococcus thermophilus

Metabolic engineering of acetaldehyde production by Streptococcus thermophilus.

The process of acetaldehyde formation by the yogurt bacterium Streptococcus thermophilus is described in this paper. Attention was focused on one specific reaction for acetaldehyde formation catalyzed by serine hydroxymethyltransferase (SHMT), encoded by the glyA gene. In S. thermophilus, SHMT also possesses threonine aldolase (TA) activity, the interconversion of threonine into glycine and ace...

Enhanced exopolysaccharide production by metabolic engineering of Streptococcus thermophilus.

It is possible that the low levels of production of exopolysaccharides (EPSs) by lactic acid bacteria could be improved by altering the levels of enzymes in the central metabolism that influence the production of precursor nucleotide sugars. To test this hypothesis, we identified and cloned the galU gene, which codes for UDP glucose pyrophosphorylase (GalU) in Streptococcus thermophilus LY03. H...

High-level acetaldehyde production in Lactococcus lactis by metabolic engineering.

Efficient conversion of glucose to acetaldehyde is achieved by nisin-controlled overexpression of Zymomonas mobilis pyruvate decarboxylase (pdc) and Lactococcus lactis NADH oxidase (nox) in L. lactis. In resting cells, almost 50% of the glucose consumed could be redirected towards acetaldehyde by combined overexpression of pdc and nox under anaerobic conditions.

Streptococcus thermophilus.

Streptocus tmophilus, as a species designation (Orla-Jensen, 1919), has included those members of the nonhemolytic streptococci that possess the unusual combination of characteristics of extreme salt sensitivity, nonobligate thermophily, a rigorous fermentative pattern with respect to certain sugars (Sherman, 1937), and, based upon attempts to culture on synthetic media, a notoriety for nutriti...

The Fermentation of Disaccharides by Streptococcus thermophilus.