THE METABOLISM OF HALOGEN-SUBSTITUTED BENZOIC ACIDS BY PSEUDOMONAS FLUORESCENS

Publisher Website
Google Scholar
Abstract
Washed suspensions of P. fluorescens, grown with benzoate as sole C source, oxidize monohalogenobenzoates in the following descending order of effectiveness benzoate, fluorobenzoates, chlorobenzoates, bromobenzoates and iodobenzoates. Cells grown on asparagine oxidize benzoate after an adaptive period of 90-120 min. This adaptive period is increased by halogenobenzoates in the following approximate descending order of effectiveness: chlorobenzoates, fluorobenzoates ( = bromobenzoates) and iodobenzoates. This inhibition of adaptation by halogeno analogues which depends on the concentration of benzoate is apparently competitive. Cells do not adapt to oxidize the halobenzoates when the halogeno analogues are inducers. However, the fluorobenzoates reduce the lag period taken to form the benzoate-oxidizing system. The halogenobenzoates inhibit adaptation to citrate and nicotinate but not so effectively as benzoate itself. This is presumably a "diauxic" effect. The analogues do not inhibit adaptation to catechol. The halogenobenzoates are not used as sole C source for growth nor do they increase growth when cells grow with asparagine as the main C source. This inability to use the analogues for growth may be due partly to inability of the cells to liberate the halogen and to carry the oxidation to a stage at which C may be assimilated and partly to the inhibition of the induction of the oxidizing enzymes.