Response of a multi species linuron degrading bacterial biofilm to - - PDF document
Response of a multi species linuron degrading bacterial biofilm to different nutrient conditions and dissolved organic matter Benjamin Horemans, Dr. Philip Breugelmans and Prof. Dirk Springael Introduction Pesticides are essential for
Benjamin Horemans, Dr. Philip Breugelmans and Prof. Dirk Springael
Introduction Pesticides are essential for agricultural practices but leads to contamination of groundwater and surface water Threath to drinkwater production and ecosystems Biodegradation plays important role in natural attenuation
Model pesticide
Model consortium:
by three‐species consortium under planktonic conditions
(Dejonghe et al., 2003)
Variovorax sp. WDL1
Variovorax
Synergistic interaction Linuron‐degrading consortium Labscale simulation growing communities as a biofilm in flow cells Acquisition of 3D‐images with CLSM and study of architecture and composition of biofilms Under natural conditions microbial communities grow predominantly as biofilms Synergistic interaction Linuron‐degrading consortium
Variovorax sp. WDL1
Confocal Laser Scanning Microscopy (CLSM) High‐Performance Liquid Chromatography (HPLC) Labscale biofilm system Linuron‐degrading consortium
0,00 0,02 0,04 0,06 0,08 0,10 0,12 5 10 15 20 25 30 35 40
Day 0 Day 5 Day 31 Day 13 Day 24
0,00 0,02 0,04 0,06 0,08 0,10 0,12 5 10 15 20 25 30 35 40 Time (days) Linuron or 3,4‐DCA concentration (mmol L‐1)
WDL1 only Consortium
Consortium biofilm development Linuron‐degrading consortium
Linuron (0.1 mM) Citrate (0.1 mM)
6,8 17,3 75,9
46,3 10,0 43,7
Spatial organization under linuron‐fed conditions reflects metabolic interactions
Structure‐function relationship Linuron‐degrading consortium
MM + Linuron + alternative C and/or N source HPLC
Linuron degradation Activity Effect of Additional C and/or N sources
Linuron or 3,4‐DCA degradation (%) ‐N +N +N ‐N +N ‐N 0.1 mM linuron 0.1 mM linuron + 0.1 mM citrate 0.1 mM linuron + 5 mM citrate
3,4‐DCA Linuron
Linuron Linuron + N Linuron + 0.1 mM citrate Linuron + N + 0.1 mM citrate Linuron + 5 mM citrate Linuron + N + 5 mM citrate
Biofilm Characteristics Effect of Additional C and/or N sources
Linuron medium Alternative media (no linuron) HPLC ~30 days 6 days
Initial irrigation medium Intermediate irrigation medium Final irrigation medium Operation time (days) Linuron degradation (%) 3,4‐DCA degradation (%) 1 0.1 mM linuron C‐ and N‐starved medium 0.1 mM linuron 11 66 (± 3) 84 (± 3) 2 0.1 mM linuron C‐starved medium 0.1 mM linuron 11 70 (± 4) 84 (± 2) 3 0.1 mM linuron N‐starved medium 0.1 mM linuron 14 72 (± 2) 85 (± 2) 4 0.1 mM linuron Alternative C and N source (0.1 mM citrate + N) 0.1 mM linuron 11 86 (± 2) 90 (± 3)
Linurondegradation Activity
Effect of Temporal Exposure to starvation or alternative C and N source
Linuron C and N starvation C starvation N starvation N + 0.1 mM citrate Linuron
Biofilm Characteristics
Effect of Temporal Exposure to starvation or alternative C and N source
Source of carbon, energy and nutrients (N, P) for heterotrophic microbial communities Quantity = concentration Quality = biodegradability community composition and abundance enzymatic activity adaptation
? Pesticide degradation
Carbon and Energy Source Dissolved Organic Matter (DOM) DOM
Increasing recalcitrance
Planktonic conditions Effect of DOM Quality and Quantity Citric acid Leachate Incubated
Linuron degradation 3,4‐DCA accumulation
Linuron 3,4‐DCA No TOC 0.4 mM DOC 1.6 mM DOC
Effect of DOM on linuron degradation in MM + 0.08 mM linuron by strain Variovorax sp. WDL1 under planktonic conditions Presence of easily‐degrabable carbon sources, besides linuron, negatively affects linuron‐degrading activity of consortium biofilms (concentration dependent) No full recovery of linuron‐degrading activity of consortium biofilms after intermittent exposure to nutrient‐starved or nutrient‐rich media changes in biofilm biomass, organization and composition particular biofilm characteristics for each condition DOM of natural origin enhances linuron‐degrading activity of Variovorax sp. WDL1 under planktonic conditions Conclusions