Degradation of dimethylamine salt of 2,4-dichlorophenoxyacetate by a mixed bacterial culture in stirred tank reactors

Oh, Keun-Yeob; Cha, Minseok

doi:10.1007/bf00129727

Cited by 3 publications

(2 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…But these investigations, carried out with a Pseudomonas cepuciu strain, were aimed at the effects of succinate as a secondary carbon source on the biodegradation of 2,4-D. Similar results concerning a transient accumulation of 2,4-dichlorophenol were also obtained during batch degradation of about 0.2 g/l of 2,4-D by a mixed bacterial culture [26]. The decreased degradation efficiency observed after several months of operation of this PU-bubble reactor could be explained by the ageing of the system owing to the high density of cells of Sphingomonas herbicidovoruns MH on the carrier, already known from continuous chloroaniline degradation [ 181 as well as from 2,4,6-tichlorophenol degradation, the latter using a polycaproamide fibre as a carrier [15].…”

Section: Oiscussionsupporting

confidence: 48%

Continuous biodegradation of phenoxyalkanoate herbicides by Sphingomonas herbicidovorans MH in a PU‐supplied bubble reactor

Hinteregger

Streichsbier

1999

Acta Biotechnologica

View full text Add to dashboard Cite

The continuous aerobic degradation of phenoxyalkanoate herbicides by Sphingomonas herbicidov o r m MH was investigated in a bubble reactor filled with modified polyurethane-foam (PU 90/51) as a camer for the adsorptive immobilization of the bacterial cells. The PU-foam was applied in the form of plates (5 x 10 x 10 mm) and the amount added was equivalent to a PU-load of 1.25% [w/vJ. Strain MH is capable of detoxifying the dichloro-substituted phenoxyalkanoates 2,4-DP, 2,4-D and 2,4-DB and the methylchloro-substituted phenoxyalkanoates MCPA. MCPP y d MCPB. Degradation of the respective substrate was followed by HPLC analyses and by determination of the chloride release. No intermediates of the degradation pathways or "dead end" products were detected by HPLC analyses. The PU-bubble reactor with immobilized 2,CDP-pre-grown cells was run continuously at 30 "C at the high dilution rate of D = 0.5 h-1 with 2,4-DP (0.2 a), and with subsequent changes to each of the other phenoxyalkanoates as a single substrate in the feed and with an intermittent return to 2.4-DP. Finally, after an intermediate substrate accumulation, 2.4-D. 2,4-DP, MCPA and MCPP could be degraded under the aforementioned conditions corresponding to a maximum degradation rate of &hen = 100 m d l x h. In the case of 2,4-DB, a slightly reduced conversion rate of about 94% could be calculated. In contrast to these results. 0.2 gA of the more recalcitrant MCPB could not be metabolized at this high dilution rate of D = 0.5 h-1 by the biofilm of Sphingomonas herbicidovorans MH, but it was degradable at a reduced dilution rate of D = 0.25 h-1.Complete detoxification of a stoichiomeuic mixture of the dichloro-and the methylchloro-substituted phenoxyalkanoates including MCPB, respectively, at a total concentration of 0.2 gll was achieved at D = 0.25 h-1, corresponding to a degradation rate of Qmt = 50 m a x h. Finally, the efficiency of the PU-immobilized cells of Sphingomonar herbicidovorans MH in detoxifying mixtures of all six herbicides could be increased to Qtot = 75 mg/l x h by the further addition of PU-foam particles corresponding to a final PU-load of 2.5% [w/v]. This PU-bubble reactor was successfully operated for more than 12 months to clean up synthetically concocted waste waters with fluctuations in phenoxyalkanoate concentration and composition.

show abstract

Section: Oiscussionsupporting

confidence: 48%

Continuous biodegradation of phenoxyalkanoate herbicides by Sphingomonas herbicidovorans MH in a PU‐supplied bubble reactor

Hinteregger

Streichsbier

1999

Acta Biotechnologica

View full text Add to dashboard Cite

show abstract

“…A bacteriostatic effect of 2,4‐DCP results from dissipating the pH gradient across the cytoplasmic membrane and causing efflux of small molecules such as ATP (Heipieper et al ., 1991). Toxicity effects of 2,4‐DCP were also observed in stirred tank reactors for microbiological treatment of 2,4‐D‐contaminated waste waters (Oh and Cha, 1996), and in 2,4‐D‐amended soils (Short et al ., 1991). Apparently, during the transition phase, 2,4‐DCP was produced faster than it became degraded and became toxic at levels higher than 0.3 mM (in the reactor medium).…”

Section: Discussionmentioning

confidence: 98%

Dynamics of multigene expression during catabolic adaptation of Ralstonia eutropha JMP134 (pJP4) to the herbicide 2,4‐dichlorophenoxyacetate

Leveau

König

Füchslin

et al. 1999

Molecular Microbiology

View full text Add to dashboard Cite

Ralstonia eutropha JMP134 carries a 22 kb DNA region on plasmid pJP4 necessary for the degradation of 2,4-D (2,4-dichlorophenoxyacetate). In this study, expression of the 2,4-D pathway genes (designated tfd ) upon exposure to different concentrations of 2,4-D was measured at a detailed timescale in chemostat-grown R. eutropha cultures. A sharp increase in mRNA levels for tfdA, tfdCDEF-B, tfdDIICIIEIIFII-BII and tfdK was detected between 2 and 13 min after exposure to 2,4-D. This response time was not dependent on the 2,4-D concentration. The genes tfdA, tfdCD and tfdDIICII were expressed immediately upon induction, whereas tfdB, tfdBII and tfdK mRNAs could be detected only around 10 min later. The number of tfd mRNA transcripts per cell was estimated to be around 200-500 during maximal expression, after which they decreased to between 1 and 30 depending on the 2,4-D concentration used for induction. Unlike the mRNAs, the specific activity of the 2,4-D pathway enzyme chlorocatechol 1,2-dioxygenase did not increase sharply but accumulated to a steady-state plateau, which was dependent on the 2, 4-D concentration in the medium. At 1 mM 2,4-D, several oscillations in mRNA levels were observed before steady-state expression was reached, which was caused by transient accumulation of the first pathway intermediate, 2,4-dichlorophenol, to toxic concentrations. Expression of tfdR and tfdS, the (identical) regulatory genes for the tfd pathway remained low and essentially unchanged during the entire adaptation phase.

show abstract

Biotransformation of p-coumaric acid and 2,4-dichlorophenoxy acetic acid by Azotobacter sp. strain SSB81

Gauri

Mandal

Dey

et al. 2012

Bioresource Technology

View full text Add to dashboard Cite

Degradation of dimethylamine salt of 2,4-dichlorophenoxyacetate by a mixed bacterial culture in stirred tank reactors

Cited by 3 publications

References 10 publications

Continuous biodegradation of phenoxyalkanoate herbicides by Sphingomonas herbicidovorans MH in a PU‐supplied bubble reactor

Continuous biodegradation of phenoxyalkanoate herbicides by Sphingomonas herbicidovorans MH in a PU‐supplied bubble reactor

Dynamics of multigene expression during catabolic adaptation of Ralstonia eutropha JMP134 (pJP4) to the herbicide 2,4‐dichlorophenoxyacetate

Biotransformation of p-coumaric acid and 2,4-dichlorophenoxy acetic acid by Azotobacter sp. strain SSB81

Contact Info

Product

Resources

About