Curtailing antibiotic use in agriculture: it is time for action: this use contributes to bacterial resistance in humans

Effect of Acid–Base Modified Biochar on Chlortetracycline Adsorption by Purple Soil

We used three purple soil (Hechuan, Jialing, and Cangxi) samples from the Jialing River basin as the research objects and added different proportions of an acid–base modified Alternanthera philoxeroides biochar (Cm) to the purple soil to study the effect of Cm on the adsorption of chlortetracycline (CTC) in the purple soil. The results indicated the following: (1) At 30 °C and pH = 6, the soil adsorption capacity increased with an increasing initial concentration of CTC. The maximum adsorption amount of CTC for each tested sample was in the range of 2054.63–3631.21 mg/kg, and the adsorption capacity in different Cm amended soils was ranked in the order of 10% Cm > 5% Cm > 2% Cm > CK. The adsorption capacity of CTC increased with an increase in the proportion of Cm. Furthermore, under the same addition ratio of Cm, Hechuan soil was found to have a better adsorption effect for CTC than Jialing and Cangxi soil. (2) The Langmuir model was the most suitable for fitting the adsorption behavior of CTC on different purple soils, and the fitting coefficients were all greater than 0.9, indicating that the adsorption of CTC on each soil sample occurred via monolayer adsorption. The thermodynamic experiment results showed that an increase in temperature was beneficial to the process of CTC adsorption, which was a spontaneous, endothermic, and entropy-adding process. (3) At pH = 6, the ionic strength ranged from 0.01 to 0.5 mol/L and the adsorption capacity of CTC of the soil samples decreased with an increase in ionic strength. In the range of pH 2–10, the adsorption capacity of CTC in all the soil samples decreased with an increase in pH. The inhibition capacity of CTC in the soil samples under acidic conditions was notably higher than that under alkaline conditions.

Selective detection for seven kinds of antibiotics with blue emitting carbon dots and Al3+ ions

In this work, we presented a facile microwave method to prepare blue emitting carbon dots (CDs) using lysine as carbon source and realized the specific detection of seven types of antibiotics by CDs and Al³⁺ ions via a two-step method. The CDs have good solubility in water and their excitation spectra are exactly coincided with the absorption of some typical antibiotics, which leads to the fluorescence quenching of CDs (OFF state). The inhibition mechanism of fluorescence is induced by the combination of inner filtering effect (IFE) and static quenching effect (SQE). In addition, the quenched fluorescence can be recovered by adding Al³⁺ ions (On state), and seven types of antibiotics can be distinguished exactly according to the emission peak position and intensity. It not only provides a new and convenient method for the detection of antibiotics, but also provides a new idea for the further application of CDs in optical sensing.

Effect of prenatal administration of low dose antibiotics on gut microbiota and body fat composition of newborn mice

Several environmental factors during the prenatal period transgenerationally affect the health of newborns in later life. Because low-dose antibiotics have been used for promoting the growth of crops and livestock in agriculture, humans may have ingested residual antibiotics for several decades. However, the effect of prenatal administration of low-dose antibiotics on newborns’ health in later life is unclear. In the present study, we found that prenatal treatment of murine mothers with low-dose antibiotics increased the abundance of bacteria of the phylum Firmicutes and the genera Clostridium IV and XIVa in feces from pups. In addition, the body fat percentage of mice in the antibiotic-treated group was higher than those in the control group at 12 weeks of age even though all pups were fed a standard diet. The body fat percentage of all mice was correlated with the abundance of fecal bacteria of Clostridium IV and XIVa. These results predict that low-dose antibiotic administration during the prenatal period affects the gut microbiota of newborns and possibly their health in later life.

Interaction of tetracycline with aluminum and iron hydrous oxides

The effect of solution chemistry (pH, sorbate-to-sorbent ratio, ionic strength (/)) and reaction time on the sorption of tetracycline to the hydrous oxides of Al (HAO) and Fe (HFO) was examined. Sorption to HAO increased with increasing pH upto pH 7 (no such trend for HFO) above which it decreased at higher pH values for both the hydrous oxides. Experimental results indicate that ligand-promoted dissolution is occurring during tetracycline sorption to these hydrous oxides. Ligand-promoted dissolution was more significantfor HAO than HFO attributable to the difference in labile surface sites between these two sorbents. The ability of tetracycline to form strong complexes with Al and Fe will increase the solubility of these minerals. Sorption of tetracycline was quite rapid and equilibrium was achieved after 8 h. However, soluble metal (Me: Al or Fe) concentrations attained equilibrium only after 24 h. Ligand-promoted dissolution appears to be a two-step process; initially, 1:1 Me-tetracycline soluble complexes are formed and as the reaction progresses 2:1 complexes existed. Increasing / (from 0.01 to 0.5 M) decreased the sorption extent only at higher sorbate-to-sorbent ratios suggesting the dominance of inner-sphere type complexes at low equilibrium tetracycline concentrations. Spectroscopic evidence indicates that tricarbonylamide and carbonyl functional groups of tetracycline could be responsible for sorption to mineral surfaces. Our research findings will increase understanding of the environmental occurrence, fate, and transport characteristics of antibiotics, which are considered as emerging organic contaminants.