P. Kiemer et al., DEGRADATION OF BENZOATE VIA BENZOYL-COENZYME-A AND GENTISATE BY BACILLUS-STEAROTHERMOPHILUS PK-1, AND PURIFICATION OF GENTISATE 1,2-DIOXYGENASE, Biology and fertility of soils, 23(3), 1996, pp. 307-313
The thermophilic Bacillus stearothermophilus PK1 utilized benzoate, 3-
hydroxybenzoate, and gentisate as sole source of carbon and energy. 2-
and 4-Hydroxybenzoate, 2,3- and 3,4-dihydroxybenzoate, and catechol d
id not support growth. Degradation of benzoate proceeded via benzoyl-c
oenzyme A (benzoyl-CoA) and gentisate. The inducible benzoyl-CoA ligas
e converted benzoate but not 3-hydroxybenzoate to its coenzyme A thioe
ster. Gentisate 1,2-dioxygenase from B. stearothermophilus PK1 was pur
ified to homogeneity. The enzyme is presumed to be a homohexamer with
a subunit molecular mass of 40 kDa. It showed maximal activity at 65-7
0 degrees C. After incubation for 80 min at 65 degrees C, 50% of the o
riginal activity was lost. Gentisate 1,2-dioxygenase activity from str
ain PK1 was strictly dependent on exogenously added Fe2+, and it was i
nhibited by, metal-chelating agents, indicating an essential role of F
e2+ in catalysis.