Fate of the antibiotic sulfadiazine in natural soils: Experimental and numerical investigations.

Based on small-scale laboratory and field-scale lysimeter experiments, the sorption and biodegradation of sulfonamide sulfadiazine (SDZ) were investigated in unsaturated sandy and silty-clay soils. Sorption and biodegradation were low in the laboratory, while the highest leaching rates were observed when SDZ was mixed with manure. The leaching rate decreased when SDZ was mixed with pure water, and was smallest with the highest SDZ concentrations.

Dynamics of transformation of the veterinary antibiotic sulfadiazine in two soils.

Veterinary antibiotics administered to livestock can be unintentionally released into the environment, for example by the application of manure to soils. The fate of such antibiotics in soils is mostly determined by sorption and degradation processes, including transformation. There is a need to further examine the combined transformation and sorption behavior of these emerging pollutants in soils.

Structural and functional response of the soil bacterial community to application of manure from difloxacin-treated pigs.

Difloxacin (DIF) belongs to the class of fluoroquinolone antibiotics that have been intensively used for the treatment of bacterial infections in veterinary and human medicine. The aim of this field study was to compare the effect of manure from DIF-treated pigs and untreated pigs on the bacterial community structure and resistance gene abundance in bulk soil and rhizosphere of maize. A significant effect of DIF manure on the bacterial community composition in bulk soil was revealed by denaturing gradient gel electrophoresis (DGGE) of bacterial 16S rRNA gene fragments amplified from total community DNA.

Effects of repeated application of sulfadiazine-contaminated pig manure on the abundance and diversity of ammonia and nitrite oxidizers in the root-rhizosphere complex of pasture plants under field conditions.

In a field experiment, the impact of repeated application of the antibiotic sulfadiazine (SDZ)-contaminated pig manure was assessed on functional microbial communities involved in ammonia and nitrite oxidation in the root-rhizosphere complexes (RRCs) of diverse plants composing a pasture. We surveyed the abundance of ammonia-oxidizing archaea (AOA) and bacteria (AOB) as well as Nitrobacter- and Nitrospira-like nitrite-oxidizing bacteria (NOB) by quantitative PCR (qPCR), and the diversity of amoA AOA and Nitrobacter-like nxrA amplicons using a cloning-sequencing approach. Whereas the first SDZ-contaminated manure application caused only slight effects on the investigated microbial communities and did not change the diversity and abundance pattern significantly, the second application of SDZ-contaminated manure induced an up to 15-fold increased ratio of AOA:AOB and a reduction of nrxA genes.

Degradation of sulfadiazine by Microbacterium lacus strain SDZm4, isolated from lysimeters previously manured with slurry from sulfadiazine-medicated pigs.

Sulfadiazine (SDZ)-degrading bacterial cultures were enriched from the topsoil layer of lysimeters that were formerly treated with manure from pigs medicated with (14)C-labeled SDZ. The loss of about 35% of the applied radioactivity after an incubation period of 3 years was attributed to CO2 release due to mineralization processes in the lysimeters. Microcosm experiments with moist soil and soil slurries originating from these lysimeters confirmed the presumed mineralization potential, and an SDZ-degrading bacterium was isolated.

Increased abundance and transferability of resistance genes after field application of manure from sulfadiazine-treated pigs.

Spreading manure containing antibiotics in agriculture is assumed to stimulate the dissemination of antibiotic resistance in soil bacterial populations. Plant roots influencing the soil environment and its microflora by exudation of growth substrates might considerably increase this effect. In this study, the effects of manure from pigs treated with sulfadiazine (SDZ), here called SDZ manure, on the abundance and transferability of sulfonamide resistance genes sul1 and sul2 in the rhizosphere of maize and grass were compared to the effects in bulk soil in a field experiment.

Long-term sorption and sequestration dynamics of the antibiotic sulfadiazine: a batch study.

Understanding the long-term sequestration of veterinary antibiotics into soil fractions with different bioavailability is important in terms of assessing their eco-toxicological impact. We performed 60-d batch sorption experiments with radiolabeled sulfadiazine (SDZ) using samples from two agricultural soils. Sequential extraction with CaCl/MeOH (easily accessible fraction), microwave (residual fraction, RES), and combustion (nonextractable residues, NER) was used to quantify the sequestration dynamics of the C-derived SDZ-equivalent concentration.

Abundance and transferability of antibiotic resistance as related to the fate of sulfadiazine in maize rhizosphere and bulk soil.

Veterinary antibiotics entering agricultural land with manure pose the risk of spreading antibiotic resistance. The fate of sulfadiazine (SDZ) introduced via manure and its effect on resistance gene levels in the rhizosphere were compared with that in bulk soil. Maize plants were grown for 9 weeks in soil fertilized with manure either from SDZ-treated pigs (SDZ treatment) or from untreated pigs (control).

Persistence of the fluoroquinolone antibiotic difloxacin in soil and lacking effects on nitrogen turnover.

The environmental risks caused by the use of fluoroquinolone antibiotics in human therapeutics and animal husbandry are associated with their persistence and (bio)accessibility in soil. To assess these aspects, we administered difloxacin to pigs and applied the contaminated manure to soil. We then evaluated the dissipation and sequestration of difloxacin in soil in the absence and presence of plants within a laboratory trial, a mesocosm trial, and a field trial.

Dissipation and sequestration of the veterinary antibiotic sulfadiazine and its metabolites under field conditions.

Veterinary antibiotics introduced into the environment may change the composition and functioning of soil microbial communities and promote the spreading of antibiotic resistance. Actual risks depend on the antibiotic's persistence and (bio)accessibility, which may differ between laboratory and field conditions. We examined the dissipation and sequestration of sulfadiazine (SDZ) and its main metabolites in soil under field conditions and how it was influenced by temperature, soil moisture, plant roots, and soil aggregation compared to controlled laboratory experiments.

Transformation and sorption of the veterinary antibiotic sulfadiazine in two soils: a short-term batch study.

The worldwide use of veterinary antibiotics poses a continuous threat to the environment. There is, however, a lack of mechanistic studies on sorption and transformation processes for environmental assessment in soils. Two-week batch sorption experiments were performed with the antibiotic sulfadiazine (SDZ) in the plow layer and the subsoil of a loamy sand and a silty loam.

Long-term sorption and desorption of sulfadiazine in soil: experiments and modeling.

Antibiotics, such as sulfadiazine (SDZ), may enter arable soil by spreading of manure of medicated husbandry or directly by the excrement of grazing animals. Knowledge of the fate of antibiotics in soils is crucial for assessing the environmental risk of these compounds, including possible transport to ground water. Kinetic sorption of (14)C-labeled SDZ (4-amino-N-pyrimidin-2-yl-benzenesulfonamide) was investigated using the batch technique.

Growth-inhibitory effects of sulfonamides at different pH: dissimilar susceptibility patterns of a soil bacterium and a test bacterium used for antibiotic assays.

The ionic speciation of sulfonamides is pH-driven and this may be crucial for their bioavailability and sorption to soil constituents, as well as for their uptake into bacterial cells. The inhibition behaviour of a bacterial test strain (Pseudomonas aeruginosa; DSM 1117), which was grown in the presence of different concentrations of 8 sulfonamides at pH values from 5 to 8, could be predicted by models that take the speciation of sulfonamides in- and outside of bacterial cells into account. Assuming a pH of 7.

Transport of sulfadiazine in soil columns: experiments and modelling approaches.

Antibiotics, such as sulfadiazine, reach agricultural soils directly through manure of grazing livestock or indirectly through the spreading of manure or sewage sludge on the field. Knowledge about the fate of antibiotics in soils is crucial for assessing the environmental risk of these compounds, including possible transport to the groundwater. Transport of (14)C-labelled sulfadiazine was investigated in disturbed soil columns at a constant flow rate of 0.

Enumeration of soil bacteria with the green fluorescent nucleic acid dye Sytox green in the presence of soil particles.

Total counts in soils are usually determined using fluorescent dyes, such as DAPI or Sybr green, due to fluorescence enhancement if they are bound to nucleic acids. Unfortunately, these commonly used dyes stain soil particles as well. Therefore, besides fluorescence enhancement, sufficient spectral differentiation is also required.

Diffuse atrazine pollution in German aquifers.

Until its prohibition in Germany in 1991, atrazine was the most frequently applied herbicide in maize cultivation. Moreover, it was used in orchards and vineyards and as a total herbicide on non-cultivated grounds (railways, factory grounds). Later on, atrazine was substituted mainly by terbutylazine.

A filtration, incubation and staining reactor including a new protocol for FISH.

A newly developed device for performing fluorescence in situ hybridization (FISH) is described. An adapted procedure was compared with two typical FISH protocols. Tests were performed with Pseudomonas cells and the gene probe EUB338.