Reasons for the Acclimation for 2,4‐D Biodegradation in Lake Water

Abstract

A study was undertaken to determine reasons for the occurrence of an acclimation period for the biodegradation of 2,4‐dichlorophenoxyacetate (2,4‐D) in lake water. The length of the acclimation period was not affected by removal of larger protozoa from the water or the presence of cycloheximide and nystatin. The population of 2,4‐D‐degrading bacteria increased long before 2,4‐D loss was detected, and herbicide loss was evident only when the population size was large. The acclimation phase was virtually eliminated if a culture of 2,4‐D‐utilizing bacteria was added to lake water. A culture of glucose‐grown 2,4‐D‐degrading bacteria metabolized the herbicide in a time interval far shorter than the acclimation phase. The time for acclimation was identical in 14 replicate samples of the same lake water. These data suggest that the length of the acclimation phase is not mainly a result of the time for reduction of grazing pressure on 2,4‐D‐degrading bacteria, the destruction of antimicrobial compounds, the decomposition of alternative C sources used preferentially to the herbicide, induction of the requisite enzymes, or the appearance of a mutant able to utilize the pesticide. The acclimation for 2,4‐D degradation in lake water appears chiefly to reflect the time for a small population of bacteria able to use the compound to become sufficiently large to cause a detectable loss of the chemical.

Survival of 2,4-dichlorophenoxyacetic acid degrading Alcaligenes eutrophus AE0106(pR0101) in lake water microcosms

“…Our finding that A. eutrophus AEO106 was the only organism able to utilize 2,4-D as a carbon source during the experiments is in accordance with previous work by Chen and Alexander [6]. These authors reported that the acclimation period for 2,4-D biodegradation in lake water was 18 days.…”

Role of inoculum preparation and density on the bioremediation of 2,4-D-contaminated soil by bioaugmentation

“…Changes in other parameters (OD, chloride and 2,4-D concentration) became measurable only when the viable cell density reached 2 × 106 cfu/ml. For all reactors, growth of BRI6001 on 1 m~ 2,4-D yielded a maximum cell density of about 1.4 × 10 ~ cfu/ ml, indicating that one cell consumed 1.5 pg of substrate, a value in relatively close agreement with that of .3 pg/cell reported by others (Chen and Alexander 1989).…”

“…1A-F). Viable cell counts demonstrated that the acclimation period reflected the time required for multiplication of a small active population in reactors inoculated with the 2,4-D-induced biomass as previosuly suggested (Chen and Alexander 1989). With the 2,4-D-uninduced biomass, the acclimation time also reflected the time for induction (0.6 day) as indicated by the viability data.…”

UV induced degradation of herbicide 2,4-D: kinetics, mechanism and effect of various conditions on the degradation

“…Absorption spectrum of 2,4-D was run in the range of 215-325 nm. The spectrum exhibited two absorption peaks at λ max : 230 nm and λ max : 283 nm [19,20]. Two different calibration curves were drawn for 2,4-D at these two different λ max values in the concentration range of 0-39 ppm as shown in Figs.…”