The Growth of Pseudomonas putida on Chlorinated Aliphatic Acids and its Dehalogenase Activity

Abstract

Two strains of Pseudomonasputida, S3 and P3, were shown to contain dehalogenase activity against monochloroacetate, dichloroacetate, 2-monochloropropionate and 2,2'-dichloropropionate but differed markedly in their levels of enzyme activity. Strain S3 had activities of less than 1 pmol substrate converted (mg protein)-l h-l and was unable to grow on any of nine chlorinated compounds tested. Strain P3 had enzyme activities 10 to 40 times greater than those of strain S3 but was capable of growth only on 2-monochloropropionate and 2,2'-dichloropropionate. In strain P3, dehalogenase activity was induced by a number of chlorinated compounds other than those that acted as growth substrates. Strain P3 dehalogenase activity dehalogenated C-2 substituted compounds. The evidence of the dehalogenase activity profiles in chemostat cultures and from thermal denaturation experiments suggested that there was more than one dehalogenase enzyme in P . putida strain P3. In crude extract, the enzyme activity was optimal at pH 7.9 to 8.1 and apparent K, values were in the millimolar range for the four major substrates, monochloroacetate, dichloroacetate, 2-monochloropropionate and 2,2'-dichloropropionate.

The Dehalogenase Complement of a Soil Pseudomonad Grown in Closed and Open Cultures on Haloalkanoic Acids

“…Growth on MCA in closed culture was not obtained since MCA at the initial concentrations usually used (0.5 g carbon 1-l) was inhibitory, and indeed growth was not obtained at 10-fold lower concentrations. This was similar to the effect of halogenated acetic acids on the growth of Pseudomonas putida PP3 previously reported (Slater et al, 1979); however, growth on these compounds can be obtained as long as continuous-flow culture systems are used to prevent the accumulation of high, toxic concentrations of halogenated alkanoic acids (Slater et al, 1979). This was achieved for Pseudomonas sp.…”

“…In addition, particularly in those strains containing two or more dehalogenases, it is possible that these organisms will provide an opportunity to study the pattern of complex regulatory mechanisms, their interaction and, perhaps, the evolution of control mechanisms. Previous studies (Slater et al, 1979;Weightman & Slater, 1980) have shown that the organism's growth rate significantly affects dehalogenase specific activities, with a pattern characteristic of catabolic enzymes (Clarke 8z Lilly, 1969;Dean, 1972).…”

“…Possession of enzymes known as dehalogenases (Jensen, 1960;Slater et al, 1979) or halidohydrolases (Goldman et al, 1968;Little &Williams, 197 1) enables micro-organisms to utilize halogenated alkanoic acids as their sole carbon and energy sources. Several bacteria have been isolated from soil with different dehalogenating capabilities towards monochloroacetic acid (MCA), dichloroacetic acid (DCA), 2-monochloropropionic acid (2MCPA) and 2,2-dichloropropionic acid (22DCPA) (Hardman & Slater,198 1).…”

Isolation and characterization of a haloalkane halidohydrolase from Rhodococcus erythropolis Y2

“…Activity stain PAGE, utilizing Ag+ to precipitate free halide ions in regions of dehalogenase activities, has been employed to identify electrophoretically distinguishable 2-haloacid halidohydrolases (Slater et al, 1979;Hardman & Slater, 1981 ;Allison et al, 1983). The same technique was used by Scholtz et al (1988) to visualize one of the dehalogenase activities in Arthrobacter sp.…”

“…Soil samples were obtained from a discharge point at an industrial site where haloalkanes had been used for several decades. Soil samples (5 g) were incubated in 250 ml screwtop bottles containing 20 ml defined growth medium (Slater et al, 1979) at pH 7.0 containing modified quantities of (1-I): Na2HP0,.12 H,O, 4 g; KH2P0,, 1 g; NaHCO,, 1 g; yeast extract, 20 mg; CoC12.6H20, 100 pg; NiC12.6 H 2 0 , 20 pg; and H3B03, 100 pg. 1-Chlorobutane was added as the sole carbon and energy source at 0.9 g 1-'.…”