title: Adaptation of Delftia acidovorans for degradation of 2,4-dichlorophenoxyacetate in a microfluidic porous medium.
abstract: Delftia acidovorans MC1071 can productively degrade R-2-(2,4-dichlorophenoxy)propionate (R-2,4-DP) but not 2,4-dichlorophenoxyacetate (2,4-D) herbicides. This work demonstrates adaptation of MC1071 to degrade 2,4-D in a model two-dimensional porous medium (referred to here as a micromodel). Adaptation for 2,4-D degradation in the 2 cm-long micromodel occurred within 35 days of exposure to 2,4-D, as documented by substrate removal. The amount of 2,4-D degradation in the adapted cultures in two replicate micromodels (~10 and 20 % over 142 days) was higher than a theoretical maximum (4 %) predicted using published numerical simulation methods, assuming instantaneous biodegradation and a transverse dispersion coefficient obtained for the same pore structure without biomass present. This suggests that the presence of biomass enhances substrate mixing. Additional evidence for adaptation was provided by operation without R-2,4-DP, where degradation of 2,4-D slowly decreased over 20 days, but was restored almost immediately when R-2,4-DP was again provided. Compared to suspended growth systems, the micromodel system retained the ability to degrade 2,4-D longer in the absence of R-2,4-DP, suggesting slower responses and greater resilience to fluctuations in substrates might be expected in the soil environment than in a chemostat.
authors: Department of Civil and Environmental Engineering, 3230C Newmark Civil Engineering Laboratory MC-250, University of Illinois at Urbana-Champaign, 205 N. Mathews Ave, Urbana, IL, 61801, USA.
authors: Hongkyu
authors: H
authors: Yoon
authors: Sabine
authors: S
authors: Leibeling
authors: Changyong
authors: C
authors: Zhang
authors: Roland H
authors: RH
authors: Müller
authors: Charles J
authors: CJ
authors: Werth
authors: Julie L
authors: JL
authors: Zilles
mesh_terms: D015084:2,4-Dichlorophenoxyacetic Acid / Q000737:chemistry / Q000378:metabolism*; D000222:Adaptation, Physiological; D061249:Batch Cell Culture Techniques; D001673:Biodegradation, Environmental; D020605:Delftia acidovorans / Q000378:metabolism*; D006540:Herbicides / Q000378:metabolism; D044085:Microfluidics; D016062:Porosity; D013379:Substrate Specificity
chemical_list: D006540:Herbicides; D015084:2,4-Dichlorophenoxyacetic Acid