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.

Lattice Boltzmann-Based Approaches for Pore-Scale Reactive Transport

“…This situation can occur during in situ bioremediation along the fringes of a contaminant plume from a persistent source where oxygen present in the ambient groundwater mixes with a dissolved organic pollutant resulting in a "reaction zone" with biomass along the plume fringe (e.g., Cirpka and Valocchi 2007;Valocchi 2012). Werth and co-workers (Zhang et al 2010b;Yoon et al 2014) have used 2-D microfl uidic pore networks to investigate these transverse reaction processes experimentally as described in the precipitation section. The electron donor and acceptor were injected through two separate inlets, allowing two substrates to mix around the central mixing zone.…”

“…As the parameter X decreases, the biofi lm permeability increases. in Zhang et al (2010b) where the biofi lm developed with the aerobic degradation of the herbicide (i.e., R-2,4-DP), Yoon et al (2014) introduced another substrate to induce adaptation of the strain to degrade a new substance on which an unadapted strain is not able to grow. Over a long term operation (~ 230 days), relatively thick and sturdy biofi lm was developed along the mixing line.…”

“…Microbial growth including extracellular polymeric substances (EPS) can signifi cantly reduce porosity and permeability by pore plugging (Davery et al 1998;Zhang et al 2010b;Kirk et al 2012;Yoon et al 2014). Additionally, biomineralization induced by urea hydrolysis and denitrifi cation processes (Nemati and Voordouw 2003;Dejong et al 2006;Martin et al 2013;Zhu et al 2013) altered porosity and fl ow patterns signifi cantly.…”

Computer simulation of submicron fluid flows in microfluidic chips and their applications in food analysis

“…Similarly, the degradation of 2,4‐dichlorophenoxyacetate in a microfluidic porous medium was carried out using Delftia acidovorans by Yoon et al. (2014).…”

Comparative Genomic Analysis of Delftia tsuruhatensis MTQ3 and the Identification of Functional NRPS Genes for Siderophore Production

“…Delftia has the ability to biodegrade organic pollutants, such as aniline [7], phenolic compounds [8], 2,4-dichlorophenoxyacetic acid (2,4- d ) [9], and acetochlor. Delftia tsuruhatensis MTQ3 (MTQ3 for short) has been isolated by our group from the rhizosphere of tobacco in Guizhou, China.…”