Characterization of novel linuron-mineralizing bacterial consortia enriched from long-term linuron-treated agricultural soils

Abstract

Linuron-mineralizing cultures were enriched from two linuron-treated agricultural soils in the presence and absence of a solid support. The cultures contained linuron-degrading bacteria, which coexisted with bacteria degrading either 3,4-dichloroaniline (3,4-DCA) or N,O-dimethylhydroxylamine (N,O-DMHA), two common metabolites in the linuron degradation pathway. For one soil, the presence of a solid support enriched for linuron-degrading strains phylogenetically related to but different from those enriched without support. Most linuron-degrading consortium members were identified as Variovorax, but a Hydrogenophaga and an Achromobacter strain capable of linuron degradation were also obtained. Several of the linuron-degrading isolates also degraded 3,4-DCA. Isolates that degraded 3,4-DCA but not linuron belonged to the genera Variovorax, Cupriavidus and Afipia. Hyphomicrobium spp. were involved in the metabolism of N,O-DMHA. Whereas several isolates degraded linuron independently, more efficient degradation was achieved by combining linuron and 3,4-DCA-degraders or by adding casamino acids. These data suggest that (1) linuron degradation is performed by a group of metabolically interacting bacteria rather than by individual strains, (2) there are other genera in addition to Variovorax that degrade linuron beyond 3,4-DCA, (3) linuron-degrading consortia of different origins have a similar composition, and (4) interactions between consortium members can be complex and can involve exchange of both metabolites and other nutrients.

Robust Linuron Degradation in On-Farm Biopurification Systems Exposed to Sequential Environmental Changes

“…(3,18,19). In the fingerprints obtained with samples of the BMs from setup L ϩ taken after week 12, no additional bands appeared.…”

Gel-Free Proteome Analysis Isotopic Labelling Vs. Label-Free Approaches for Quantitative Proteomics

“…SRS16 cultured in the presence or absence of the phenylurea herbicide linuron. This strain has already been shown to catabolise linuron (Breugelmans et al, 2007), and we have already performed gel-based (Breugelmans et al, 2010) as well as isotopic labelling gel-free proteomic analyses on these samples (Bers et al, In Press), indicating us what changes should be expected. All three biological replicates were injected three times, and only proteins identified in at least 2 out of the 3 technical replicates as well as in each biological replicate were considered for quantification.…”

Metabolic Fate of [14C]Diuron and [14C]Linuron in Wheat (Triticum aestivum) and Radish (Raphanus sativus)

“…Radioactivity of plant parts and of nonextractable residues was measured after oxidative combustion of aliquots in an oxidizer (model Packard 307, PerkinElmer Life and Analytical Sciences, Courtaboeuf, France). The resulting 14 CO 2 was trapped in a scintillation mixture (Permafluor and Carbosorb, PerkinElmer LAS) and counted in a Packard Tricarb 2200CA scintillation counter. Aliquots of extractable residues were directly counted with Ultimagold (PerkinElmer LAS) as scintillation cocktail.…”

“…[U-phenyl- 14 C]Linuron (specific activity 1.92 Â 10 9 Bq mmol -1 , radiochemical purity >98% as determined by radio-RP-HPLC analysis) was purchased from Izotop (Budapest, Hungary). , radiochemical purity >97% as determined by radio-RP-HPLC analysis), linuron (98% pure), diuron (97% pure), almond β-glucosidase (G-0395), rabbit liver esterase (E-9636), potassium phosphate, sucrose, myoinositol, thiamine, and 2,4-dichlorophenoxyacetic acid were purchased from SigmaAldrich (Saint-Quentin-Fallavier, France).…”

“…Bacterial degradation results in the formation of 3-(3,4-dichlorophenyl)-1-methylurea and 3,4-dichloroaniline that exhibit greater toxicological effects than those of the parent compounds. However, these metabolites can sometimes be further completely mineralized (13,14). In mammals, 3-(3,4-dichlorophenyl)-1-methoxyurea, 3-(3,4-dichlorophenyl)urea and 3-(6-hydroxy-3,4-dichlorophenyl)urea were identified as major metabolites of linuron and are excreted in the urine as glucuronide or sulfate conjugates (15).…”