0000000000322335
AUTHOR
Edward Topp
Evidence for the adaptation of bacterial populations to antibiotics degradation in agricultural soils
A recent study has reported accelerated biodegradation of antibiotics in agricultural soils repeatedly amended with sewage manure contaminated by veterinary antibiotics. This pioneer work carried out by the research team directed by Dr E Topp (Agriculture and Agri-Food Canada) led to the characterization of sail microbial communities able to degrade sulfamethazine, an antibiotic belonging to sulphonamides. They showed that up to 30% of 14C0
Bioremediation of atrazine-contaminated soil
International audience
Distribution and characteristics of Listeria monocytogenes isolates from surface waters of the South Nation River Watershed, Ontario, Canada
ABSTRACT Listeria monocytogenes is a facultative intracellular pathogen thought to be widely distributed in the environment. We investigated the prevalence and characteristics of L. monocytogenes isolates from surface waters derived from catchments within the South Nation River watershed (Ontario, Canada). This watershed is dominated by urban and rural development, livestock and crop production, and wildlife habitats. From June to November 2005, a total of 314 surface water samples were collected biweekly from 22 discrete sampling sites characterized by various upstream land uses. Presumptive Listeria spp. were isolated using a selective enrichment and isolation procedure, and 75 L. monocyt…
Dependence of accelerated degradation of atrazine on soil pH in French and Canadian soils
Abstract A series of agricultural soils varying in their atrazine treatment history were sampled from 12 sites in France and two sites in Canada. The soils varied widely with respect to soil chemical, physical and microbiological (total microbial biomass, kinetics of C and N mineralization) properties. Soils treated with as few as two successive atrazine field applications mineralized [U- ring - 14 C]atrazine significantly more rapidly in 35 d laboratory incubations than did soils which had never received atrazine. Longer treatment history tended to favour more rapid mineralization in the so-called “adapted” soils. Up to 80% of the initially applied 14 C-atrazine was mineralized at the end …
Isolation and characterisation of Nocardioides sp. SP12, an atrazine-degrading bacterial strain possessing the gene trzN from bulk- and maize rhizosphere soil
International audience; We report the characterisation of Nocardioides sp. SP12, an atrazine-degrading bacteria isolated from atrazine-treated bulk- and maize rhizosphere soil. Based on 16S rDNA alignment, strain SP12 showed close phylogenic relationships with Nocardioides sp. C157 and Nocardioides simplex. Internal transcribed spacer (ITS) sequences of strain SP12 were longer than those of other Nocardioides sp. and present Ala- and Ile-tRNA unlike Actinomycetales. Nocardioides sp. SP12 presents a novel atrazine catabolic pathway combining trzN with atzB and atzC. Atrazine biodegradation ends in a metabolite that co-eluted in HPLC with cyanuric acid. This metabolite shows an absorption spe…
Long Term Exposure of Agricultural Soil to Veterinary Antibiotics Changes the Population Structure of Symbiotic Nitrogen-Fixing Bacteria Occupying Nodules of Soybeans (Glycine max)
International audience; Antibiotics can be entrained onto agricultural land through the application of animal manures, human biosolids, or recycled wastewater for irrigation. In order to evaluate the impacts on soil microorganisms of exposure to antibiotics, a series of replicated plots were initiated in 1999 at the AAFC research farm in London ON. Every spring a mixture of sulfamethazine, chlortetracycline and tylosin is incorporated directly into the soil to attain concentrations ranging from 0.1 to 10 mg/kg, and these are then seeded with soybeans. In the present study nodules were isolated from soybean plants growing in antibiotic treated and control soils in 2012, after 14 annual treat…
Bacterial community analysis by denaturing gradient gel electrophoresis, second edition
Chapitre 43; absent