Acetaldehyde: an intermediate in the formation of ethanol from glucose by lactic acid bacteria.
Group N streptococci formed acetaldehyde and ethanol from glucose. As the enzymes aldehyde dehydrogenase, phosphotransacetylase and acetate kinase were present this would enable these organisms to reduce acetyl-CoA to acetaldehyde and convert acetyl-CoA to acetyl phosphate and acetate. A pentose phosphate pathway which converted ribose-5-phosphate to glyceraldehyde-3-phosphate was also present. Acetaldehyde could not be formed via the hexose monophosphate shunt or by direct decarboxylation of pyruvate, as the enzymes phosphoketolase and alpha-carboxylase were absent. Phosphoketolase activity was induced in Streptococcus lactis subsp. diacetylactis after growth on D-xylose. Group N streptococci also contained an NAD-dependent alcohol dehydrogenase which reduced acetaldehyde to ethanol while both NAD- and NADP-dependent alcohol dehydrogenase activities were found in Leuconostoc cremoris.
D000079:Acetaldehyde / Q000378:metabolism*; D000429:Alcohol Oxidoreductases / Q000378:metabolism; D000445:Aldehyde Oxidoreductases / Q000378:metabolism; D000446:Aldehyde-Lyases / Q000378:metabolism; D002474:Cell-Free System; D000431:Ethanol / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D007778:Lactobacillus / Q000378:metabolism*; D007934:Leuconostoc / Q000378:metabolism; D008956:Models, Chemical; D010376:Pediococcus / Q000378:metabolism; D010709:Phosphate Acetyltransferase / Q000378:metabolism; D010770:Phosphotransferases / Q000378:metabolism; D011767:Pyruvate Decarboxylase / Q000378:metabolism; D013289:Streptococcaceae / Q000378:metabolism*; D013291:Streptococcus / Q000378:metabolism
D000431:Ethanol; D000429:Alcohol Oxidoreductases; D000445:Aldehyde Oxidoreductases; D010709:Phosphate Acetyltransferase; D010770:Phosphotransferases; D011767:Pyruvate Decarboxylase; D000446:Aldehyde-Lyases; D000079:Acetaldehyde; D005947:Glucose