Louise Feld

Establishment of bacterial herbicide degraders in a rapid sand filter for bioremediation of phenoxypropionate polluted groundwater

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  • Louise Feld
  • Tue Kjærgaard Nielsen
  • ,
  • Lars Hestbjerg Hansen
  • ,
  • Jens Aamand, Department of Geochemistry, Geological Survey of Denmark and Greenland (GEUS), Copenhagen, Denmark
  • ,
  • Christian Nyrop Albers, Department of Geochemistry, Geological Survey of Denmark and Greenland (GEUS), Copenhagen, Denmark

In this study, we investigated the establishment of natural bacterial degraders in a sand filter treating groundwater contaminated with the phenoxypropionate herbicides MCPP and DCPP and the associated impurity/catabolite 4-CPP. A pilot facility was set up in a contaminated landfill-site. Anaerobic groundwater was pumped up and passed through an aeration basin and subsequently through a rapid sand filter, which is characterized by a low residence time of the water in the filter. During three months, degradation of DCPP, MCPP and 4-CPP in the sand filter increased to 15-30% of the inlet concentration. A significant selection for natural bacterial herbicide degraders also occurred in the sand filter. Using a Most Probable Number (MPN) method, we found a steady increase in the number of culturable phenoxypropionate degraders, reaching approximately 5×10(5) degraders per g sand, by the end of the study. Using qPCR targeting the two phenoxypropionate degradation genes rdpA and sdpA encoding stereo-specific dioxygenases, a parallel increase was observed, but with gene copy numbers around 2-3 log higher than the MPN. Generally, the sdpA genes were more abundant than the rdpA genes and establishment of a significant population of bacteria harboring sdpA occurred faster than for the rdpA gene carrying population.The identity of specific herbicide degraders in the sand filter was assessed by Illumina MiSeq sequencing of 16S rRNA genes from sand filter samples and from selected MPN wells. We propose a list of potential degrader bacteria being involved in the herbicide degradation, including representatives belonging to the Comamonadaceae and Sphingomonadales.

Original languageEnglish
JournalApplied and Environmental Microbiology
Volume82
Issue3
Pages (from-to)878-887
ISSN0099-2240
DOIs
Publication statusPublished - Feb 2016

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