Industrial Biotransformations

Acetolactate decarboxylase
Bacillus brevis
1) Reaction conditions
[2]: < 1.13 µM, < 0.1 mg · L –1 [88.11 g · mol –1 ]
pH: < 4.0
T: 13°C
medium: aqueous
reaction type: decarboxylation
catalyst: solubilized enzyme
enzyme: (S)-2-hydroxy-2-methyl-3-oxobutanoate carboxy-lyase
(α-acetolactate decarboxylase)
strain: Bacillus brevis
CAS (enzyme): [9025-02–9]
2) Remarks
O
HO
1
COOH
● During beer fermentation diacetyl is formed by a non-enzymatic oxidative decarboxylation of
α-acetolactate.
● Diacetyl has a very low flavor threshhold, compared with acetoin.
EC 4.1.1.5
1 = α-acetolactate
2 = acetoin Novo Nordisk
Fig. 4.1.1.5 – 1
E
- CO 2
● The problem is the slow reaction rate for the conversion of α-acetolactate to diacetyl with subsequent
conversion of diacetyl to acetoin. The addition of acetolactate decarboxylase allows the
bypassing of the slow oxidation step:
O
2
OH
449