Biofilm formation of a bacterial consortium on linuron at micropollutant concentrations in continuous flow chambers and the impact of dissolved organic matter

Abstract

Bacterial multispecies biofilms are catalysts for pollutant degradation in aqueous ecosystems. Their activity in systems where xenobiotics occur as micropollutants (μg L(-1) level) and natural dissolved organic matter provides carbon and energy instead remains uncharacterized. Biofilm formation of a bacterial consortium consisting of the linuron-degrading Variovorax sp. WDL1 and metabolite-degrading strains Comamonas sp. WDL7 and Hyphomicrobium sp. WDL6 at micropollutant linuron concentrations and the impact of auxiliary carbon sources on degradation and biofilm composition were investigated. Biofilms formed at concentrations of 1000, 100, and 10 μg L(-1) linuron. The highest biomass, organized in mixed-species mounds, was observed at 1000 μg L(-1) linuron, while at 100 and 10 μg L(-1) , thin layers of cells occurred. Linuron removal efficiencies decreased from c. 85% when fed with 100 and 1000 μg L(-1) linuron to 30% in case of 10 μg L(-1) linuron due to reduced specific activity. Biofilms grown on 10 μg L(-1) linuron were subsequently fed with easily and less degradable carbon sources in addition to 10 μg L(-1) linuron. Although co-feeding with more degradable C-sources increased biofilm biomass, linuron removal remained 30%. Calculations based on biofilm volume measurements pointed toward reduced specific activity, compensated by a higher biomass. Uncertainties about biofilm heterogeneity and cell volume can undo this explanation.

From full-scale biofilters to bioreactors: Engineering biological metaldehyde removal

“…In addition, Wiggins and Alexander (1988) reported that the lag time of bacteria to p-nitrophenol (PNP) was less at higher PNP acclimation concentration due to growth of a small number of functional degraders within the microbiome. In biofilms a similar trend was observed where the linuron removal efficiency was ~80% at between 100 -1000 µg L -1 but 35% at 10 µg L -1 of linuron (Horemans et al, 2014). Models by Rittmann (2002) predicted that a quick loss of activity could follow these improvements.…”

Catabolic task division between two near‐isogenic subpopulations co‐existing in a herbicide‐degrading bacterial consortium: consequences for the interspecies consortium metabolic model

“…A cryoculture of WDL1 was plated on R2A supplemented with linuron, a smear of grown cells was inoculated in R2B supplemented with linuron, and grown until exponential phase (OD 600 0.15). To assure the Lin+ and DCA+ phenotype of the culture, depletion of linuron and DCA was verified by determining their concentrations on a regular basis by High Performance Liquid Chromatography (HPLC) analysis as reported by Horemans and colleagues (). Genomic DNA was extracted from 1‐mL culture using the Puregene Core kit A (Qiagen, Belgium) following the manufacturer's instructions.…”

“…R2B was used as background medium to provide an additional source of carbon to acquire sufficient biomass for activity. After one week, 1‐ml samples were taken, centrifuged at 10 000 × g for 5 min, and the supernatant stored at −20°C until HPLC for determining linuron and DCA concentration (Horemans and colleagues ().…”

PromA Plasmids Are Instrumental in the Dissemination of Linuron Catabolic Genes Between Different Genera

“…Briefly, 1 g of the matrix material was inoculated into 50 mineral medium MMO (Dejonghe et al, 2003) containing 20 mg/L linuron. Degradation of linuron was monitored using HPLC as described before (Horemans et al, 2014). After linuron was degraded, dilutions of the enrichment culture were plated on R2A medium (Breugelmans et al, 2007) containing 20 mg/L linuron.…”