Biochemistry

The reduction of acetaldehyde to ethyl alcohol is completed by alcoholic fermentation. CM CHfCH 2 0H Ethanol HCOOH Formic acid СНгСНгСН г -СН 2 0Н Butanol CHfCO — CH5 Acetone CH j -CHOH-CH j Isopropanol CHj-CO-CKOH-CHj Acetoin C0 z CHj-COOH Acetic acid GHf-CHOH-COOH Lactic acid CHf~CH 2 ~C00H Propionic acid CHf-CHfCH 2 -G00H Butyric acid H00C — CHi~CHfC00H Succinicacid Carbon dioxide Иг Hydrogen CH ( Methane Figure 11.9 - The types of fermentation Lactic-acid fermentation - is the conversion of sugar by the action of enzymes of lactic-acid bacteria into lactic acid. Homo and hetero fermentativelactic-acid fermentation are distinguished. During homofermentativefermentation, microorganisms ferment hexoses, mainly to lactic acid, and only trace amounts of by-productsare formed: volatile acids, ethanol, fumaric acid, and CO 2 . The overall equation of this type of fermentation: C 6 H 12 O 6 + 2ADP + 2F H -» 2CH 3 - CHOH - COOH + 2ATP. sugar lactic acid Schematically heterofermentative lactic-acid fermentation can be represented by the following equation: 238