Fig. 2.

The metabolic pathways for 2,3-butanediol synthesis in bacteria (modified, based on Magee & Kosaric, 1987). 1, glycolysis and pentose phosphate pathway enzymes; 2, pyruvate kinase; 3, α-acetolactate synthase; 4,α-acetolactate decarboxylase; 5, acetoin reductase (2,3-butanediol dehydrogenase); 6, pyruvate–formate lyase; 7, phospho-transacetylase; 8, acetate kinase; 9, acetaldehyde dehydrogenase; 10, ethanol dehydrogenase; 11, actate dehydrogenase; 12, phosphoenolpyruvate decarboxylase ; 13, malate dehydrogenase; 14, fumarase; 15, succinate dehydrogenase.