Publication Details |
| Category | Text Publication |
| Reference Category | Journals |
| DOI | 10.1007/s10532-005-6894-8 |
| Document | Shareable Link |
| Title (Primary) | 2,4-Dichlorophenoxyacetic acid (2,4-D) utilization by Delftia acidovorans MC1 at alkaline pH and in the presence of dichlorprop is improved by introduction of the tfdK gene |
| Author | Hoffmann, D.; Müller, R.H. |
| Source Titel | Biodegradation |
| Year | 2006 |
| Department | UMB |
| Volume | 17 |
| Issue | 3 |
| Page From | 263 |
| Page To | 273 |
| Language | englisch |
| Abstract | Growth of Delftia acidovorans MC1 on 2,4-dichlorophenoxyacetic acid (2,4-D) and on racemic 2-(2,4-dichlorophenoxy)propanoic acid ((RS)-2,4-DP) was studied in the perspective of an extension of the strain’s degradation capacity at alkaline pH. At pH 6.8 the strain grew on 2,4-D at a maximum rate (μmax) of 0.158 h−1. The half-maximum rate-associated substrate concentration (K s) was 45 μM. At pH 8.5 μmax was only 0.05 h−1 and the substrate affinity was mucher lower than at pH 6.8. The initial attack of 2,4-D was not the limiting step at pH 8.5 as was seen from high dioxygenase activity in cells grown at this pH. High stationary 2,4-D concentrations and the fact that μmax with dichlorprop was around 0.2 h−1 at both pHs rather pointed at limited 2,4-D uptake at pH 8.5. Introduction of tfdK from D. acidovorans P4a by conjugation, coding for a 2,4-D-specific transporter resulted in improved growth on 2,4-D at pH 8.5 with μmax of 0.147 h−1 and K s of 267 μM. Experiments with labeled substrates showed significantly enhanced 2,4-D uptake by the transconjugant TK62. This is taken as an indication of expression of the tfdK gene and proper function of the transporter. The uncoupler carbonylcyanide m-chlorophenylhydrazone (CCCP) reduced the influx of 2,4-D. At a concentration of 195 μM 2,4-D, the effect amounted to 90% and 50%, respectively, with TK62 and MC1. Cloning of tfdK also improved the utilization of 2,4-D in the presence of (RS)−2,4-DP. Simultaneous and almost complete degradation of both compounds occurred in TK62 up to D = 0.23 h−1 at pH 6.8 and up to D = 0.2 h−1 at pH 8.5. In contrast, MC1 left 2,4-D largely unutilized even at low dilution rates when growing on herbicide mixtures at pH 8.5. |
| Persistent UFZ Identifier | https://www.ufz.de/index.php?en=20939&ufzPublicationIdentifier=2719 |
| Hoffmann, D., Müller, R.H. (2006): 2,4-Dichlorophenoxyacetic acid (2,4-D) utilization by Delftia acidovorans MC1 at alkaline pH and in the presence of dichlorprop is improved by introduction of the tfdK gene Biodegradation 17 (3), 263 - 273 10.1007/s10532-005-6894-8 |
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