Transformation of mono- and dichlorinated phenoxybenzoates by phenoxybenzoate-dioxygenase in pseudomonas pseudoalcaligenes POB310 and a modified diarylether-metabolizing bacterium.
Pseudomonas pseudoalcaligenes POB310 contains genes that encode phenoxybenzoate dioxygenase. The enzyme transforms mono- and dichlorinated phenoxybenzoates to yield protocatechuate that is used as a growth substrate and chlorophenols that are nonmetabolizable. Mass spectral analysis of (18)O metabolites obtained from the protocatechuate 3,4-dioxygenase-deficient mutant, POB310-B1, suggested that the reaction mechanism is a regioselective angular dioxygenation. A cloning vector containing reaction relevant genes (pD30.9) was transferred into Pseudomonas sp. strain B13 containing a modified ortho-cleavage pathway for aromatic compounds. The resultant Pseudomonas sp. strain B13-D5 (pD30.9) completely metabolized 3-(4-chlorophenoxy)benzoate. During growth on 3-phenoxybenzoate, strain B13-D5 (pD30.9) (K(s) = 0.70+/-0.04 mM, mu(max) = 0.45+/-0.03 h(-1), t(d) = 1.5 h, Y = 0.45+/-0.03 g bio- mass x g substrate(-1)) was better adapted to low substrate concentrations, had a faster rate of growth, and a greater yield than POB310 (K(s) = 1.13+/-0.06 mM, mu(max) = 0.31+/-0.02 h(-1), t(d) = 2.2 h, Y = 0.39+/-0.02 g biomass. g substrate(-1)).
Halden
R U
RU
Department of Civil Engineering, University of Minnesota, Minneapolis, Minnesota 55455, USA.
Peters
E G
EG
Halden
B G
BG
Dwyer
D F
DF
D001426:Bacterial Proteins; D001565:Benzoates / Q000378:metabolism*; D004790:Enzyme Induction; D006899:Mixed Function Oxygenases / Q000096:biosynthesis / Q000378:metabolism*; D011549:Pseudomonas / Q000201:enzymology* / Q000254:growth & development; D013379:Substrate Specificity
D001426:Bacterial Proteins; D001565:Benzoates; D006899:Mixed Function Oxygenases; C092910:PobB protein, Pseudomonas pseudoalcaligenes