Anaerobic degradation of 3-hydroxybenzoate by a newly isolated nitrate-reducing bacterium.
A Gram-negative nitrate-reducing bacterium, strain Asl-3, was isolated from activated sludge with nitrate and 3-hydroxybenzoate as sole source of carbon and energy. The new isolate was facultatively anaerobic, catalase- and oxidase-positive and polarly monotrichously flagellated. In addition to nitrate, nitrite, N2O, and O2 served as electron acceptors. Growth with 3-hydroxybenzoate and nitrate was biphasic: nitrate was completely reduced to nitrite before nitrite reduction to N2 started. Benzoate, 3-hydroxybenzoate, 4-hydroxybenzoate, protocatechuate or phenyl-acetate served as electron and carbon source under aerobic and anaerobic conditions. During growth with excess carbon source, poly-beta-hydroxybutyrate was formed. These characteristics allow the affiliation of strain Asl-3 with the family Pseudomonadaceae. Analogous to the pathway of 4-hydroxybenzoate degradation in other bacteria, the initial step in anaerobic 3-hydroxybenzoate degradation by this organism was activation to 3-hydroxy-benzoyl-CoA in an ATP-consuming reaction. Cell extracts of 3-hydroxybenzoate-grown cells exhibited 3-hydroxybenzoyl-CoA synthetase activity of 190 nmol min-1 mg protein-1 as well as benzoyl-CoA synthetase activity of 86 nmol min-1 mg protein-1. A reductive dehydroxylation of 3-hydroxybenzoyl-CoA could not be demonstrated due to rapid hydrolysis of chemically synthesized 3-hydroxybenzoyl-CoA by cell extracts.
Heising
S
S
Lehrstuhl für Mikrobiologie I, Eberhard-Karls-Universität, Tübingen, F.R.G.
Brune
A
A
Schink
B
B
D000693:Anaerobiosis; D003066:Coenzyme A Ligases / Q000032:analysis; D006090:Gram-Negative Bacteria / Q000201:enzymology / Q000302:isolation & purification / Q000378:metabolism*; D062385:Hydroxybenzoates / Q000378:metabolism*; D009566:Nitrates / Q000378:metabolism*; D009573:Nitrites / Q000378:metabolism; D009609:Nitrous Oxide / Q000378:metabolism; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism
D062385:Hydroxybenzoates; D009566:Nitrates; D009573:Nitrites; C032948:3-hydroxybenzoic acid; D003066:Coenzyme A Ligases; D009609:Nitrous Oxide; D010100:Oxygen