Function
Catalyzes the reversible reduction of (S)-acetoin to (S,S)-butane-2,3-diol (L-BD) in the presence of NADH. To a lesser extent, can also catalyze the irreversible reduction of diacetyl to (S)-acetoin. Cannot oxidize meso-BD, D-BD, 2-butanol, 1,2-propanediol, ethanol, acetol, 1,2-butanediol, 1,3-butanediol, n-butanol, and n-propanol. Cannot reduce (R)-acetoin, acetol, dihydroxyacetone and 2,4-pentanedione.