Anaerobic degradation of 3-halobenzoates by a denitrifying bacterium.
A denitrifying bacterium was isolated from a river sediment after enrichment on 3-chlorobenzoate under anoxic, denitrifying conditions. The bacterium, designated strain 3CB-1, degraded 3-chlorobenzoate, 3-bromobenzoate, and 3-iodobenzoate with stoichiometric release of halide under conditions supporting anaerobic growth by denitrification. The 3-halobenzoates and 3-hydroxybenzoate were used as growth substrates with nitrate as the terminal electron acceptor. The doubling time when growing on 3-halobenzoates ranged from 18 to 25 h. On agar plates with 1 mM 3-chlorobenzoate as the sole carbon source and 30 mM nitrate as the electron acceptor, strain 3CB-1 formed small colonies (1-2 mm in diameter) in 2 to 3 weeks. Anaerobic degradation of both 3-chlorobenzoate and 3-hydroxybenzoate was dependent on nitrate as an electron acceptor and resulted in nitrate reduction corresponding to the stoichiometric values for complete oxidation of the substrate to CO2. 3-Chlorobenzoate was not degraded in the presence of oxygen. 3-Bromobenzoate and 3-iodobenzoate were also degraded under denitrifying conditions with stoichiometric release of halide, but 3-fluorobenzoate was not utilized by the bacterium. Utilization of 3-chlorobenzoate was inducible, while synthesis of enzymes for 3-hydroxybenzoate degradation was constitutively low, but inducible. Degradation was specific to the positive of the halogen substituent, and strain 3CB-1 did not utilize 2- or 4-chlorobenzoate.
Häggblom
M M
MM
Environment, Cook College, Rutgers, State University of New Jersey, New Brunswick 08901, USA. haggblom@aesop.rutgers.edu
Young
L Y
LY
D000693:Anaerobiosis; D001565:Benzoates / Q000378:metabolism*; D001673:Biodegradation, Environmental; D001970:Bromobenzoates / Q000378:metabolism; D002723:Chlorobenzoates / Q000378:metabolism; D006090:Gram-Negative Bacteria / Q000254:growth & development / Q000302:isolation & purification / Q000378:metabolism*; D007463:Iodobenzoates / Q000378:metabolism; D009566:Nitrates / Q000378:metabolism; D009573:Nitrites / Q000378:metabolism; D014871:Water Microbiology
D001565:Benzoates; D001970:Bromobenzoates; D002723:Chlorobenzoates; D007463:Iodobenzoates; D009566:Nitrates; D009573:Nitrites; C036427:3-chlorobenzoic acid