Transformation of mono- and dichlorinated phenoxybenzoates by phenoxybenzoate-dioxygenase in Pseudomonas pseudoalcaligenes POB310 and a modified diarylether-metabolizing bacterium
✍ Scribed by Rolf U. Halden; Eric G. Peters; Barbara G. Halden; Daryl F. Dwyer
- Book ID
- 101243522
- Publisher
- John Wiley and Sons
- Year
- 2000
- Tongue
- English
- Weight
- 105 KB
- Volume
- 69
- Category
- Article
- ISSN
- 0006-3592
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✦ Synopsis
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-dioxygenasedeficient 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-(4chlorophenoxy)benzoate. During growth on 3-phenoxybenzoate, strain B13-D5 (pD30.9) (K s = 0.70 ± 0.04 mM, µ max = 0.45 ± 0.03 h -1 , t d = 1.5 h, Y = 0.45 ± 0.03 g biomass и 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, µ max = 0.31 ± 0.02 h -1 , t d = 2.2 h, Y = 0.39 ± 0.02 g biomass и g substrate -1 ).