Antibiotics pollution in Jiulong River estuary: source, distribution and bacterial resistance

To gain insight into the antibiotic pollution in the Jiulong River estuary and the pollutant sources, we analyzed the concentration of 22 widely-used antibiotics in water samples collected from the river and estuary, 17 and 18 sampling sites, respectively. Contamination with sulfonamides, quinolones and chloramphenicols was frequently detected and the distribution pattern of antibiotics suggested that most of the pollutants are from the Jiulong River, especially from the downstream watersheds. To reveal the ecological effects, we isolated 35 bacterial strains from the estuary and analyzed their antibiotic resistance to the eight most frequently detected antibiotics. The bacteria were subsequently classified into seven different genera by 16SrDNA sequencing. Up to 97.1% of the bacteria showed resistance and 70.6% of strains showed multi-resistance to these antibiotics, especially to sulfonamides. This study demonstrated a pattern of antibiotic contamination in the Jiulong River and its estuary and illustrated high bacterial antibiotic resistance which was significantly correlated with the average antibiotics concentrations and detected frequencies in the estuary.     

Occurrence and fate of typical antibiotics in wastewater treatment plants in Harbin,North-east China

• The concentration distributions and removals of 12 antibiotics were investigated. • Macrolides and fluoroquinolones presented relatively higher concentrations. • The removal of antibiotics did not differ among the different treatment processes. As a new pollutant, antibiotics in the environment and their removal in wastewater treatment plants (WWTPs) have gained considerable attention. However, few studies investigated antibiotics in the north-eastern areas of China. By employing high-performance liquid chromatography-tandem mass spectrometry, the concentration distribution and removal of 12 antibiotics belonging to four types (cephalosporins, sulfonamides, fluoroquinolones, and macrolides) were investigated in influents and effluents as well as the removal efficiencies of four typical treatment processes in 18 wastewater treatment plants of Harbin City, north-eastern China. Macrolides and fluoroquinolones presented relatively higher detection concentrations and rates both in the water and in the sludge phases. Sulfonamides and cephalosporins displayed higher detection concentrations in the water phase. The representative antibiotics in influents and effluents included ROX, NOR, OFL, SMX, AZI, and CLA, with detection rates above 95%. The detection rates of the other six antibiotics exceeded 30%. In the sludge, the other five antibiotics, except SMX, presented relatively higher detection concentrations and rates, with detection rates greater than 95%. For cephalosporin, the detection rates of CTX and CFM in the sludge were 0. The removal efficiencies for the 12 antibiotics differed greatly, with average values ranging from 30% to 80% and the highest values for cephalosporin. The removal of antibiotics did not differ significantly among the four different treatment processes.     

Degradation of sulfonamides during anaerobic composting of swine manure

Residual antibiotics in manure pose a potential threat to public and ecological health as a result of the application of manure from animals treated with antibiotics to land. The environmental fate of sulfonamides (SAs) in swine manure after composting and field application remains largely unknown. We studied the degradation of the antibiotics sulfadiazine (SD), sulfathiazole (ST), and sulfamethazine (SM2) during anaerobic composting. We tested the effects of temperature and antibiotic concentration on degradation rates. We also evaluated the changes in pH, moisture, and biological degradation material in manure spiked with SAs and in a control. Results showed that the 3 SAs decreased by between 52.31% and 90.30% in all 9 treatments following 14 days of anaerobic composting, and the highest removal efficiencies were observed at a temperature of 35°C and initial concentrations of 6.03, 6.48, and 6.32?µg/g of SD, ST, and SM2, respectively, which were degraded by 90.30%, 85.78%, and 75.18%. Removal efficiencies for all SAs correlated well with moisture and biological degradation material of the manure. These results indicate that composting may be a practical and effective way to reduce concentrations of these three SAs in swine manure prior to its land application.     

Optimization of analytical methods to improve detection of erythromycin from water and sediment

Analytical methods to improve the detection of erythromycin in water and sediment were developed to optimize for erythromycin's recovery of extractable and bound residues from the aquatic environment. The objective of this study was to determine optimal recovery of erythromycin from water and sediment to improve its detection in environmental samples through solid-phase extraction (SPE) and sediment-extraction methods. SPE methods examined included previously reported methods for macrolide and sulfonamide antibiotics with erythromycin recoveries ranging from 75.5 % to 94.7 %. Extraction of erythromycin was performed from sand employing various solvents and buffers to determine the best method for extraction from two sandy loam pond sediments. Various extraction times were also examined, and all extraction procedures were performed in duplicate. The greatest recovery of ¹⁴C-erythromycin in the Iowa sediment was 84 % using 0.3 M ammonium acetate at pH 4.2: acetonitrile (15:85, v/v) solution. The Oklahoma sediment yielded the greatest recovery of ¹⁴C-erythromycin at 86.7 % with 0.3 M ammonium acetate at pH 7: acetonitrile (30:70, v/v) with a 60-minute shake time. The present results demonstrate improved extraction methods for enhancing the accuracy of erythromycin detection from environmental samples.     

Environmental fate of tetracycline resistance genes originating from swine feedlots in river water

Tetracyclines are antibiotics commonly used in swine farms to treat disease and promote growth. However, there are growing concerns regarding the discharge of animal feces into the environment owing to the potential for development and dissemination of tetracycline resistance genes (TRGs). In this study, farming wastewater from one Chinese swine farm as well as river water from seven locations downstream of the farm was sampled. Polymerase chain reaction (PCR) showed that 12 TRGs, including six efflux pump genes (tet(B), tet(C), tet(D), tet(E), tet(G) and tet(L)), five ribosomal protection proteins (RPPs) genes (tet(O), tet(M), tet(Q), tet(W) and tet(S)), and one enzymatic modification gene (tet(X)), were present in all wastewater and river water samples. Quantitative real-time PCR (qPCR) showed that the abundance of tet(C), tet(X), tet(O), tet(M), tet(Q) and tet(W) decreased with downstream flow. Among the detected TRGs, tet(C) had the highest abundance, ranging from 459.5 copies/16S rRNA gene copies in wastewater to 33.8 copies/16S rRNA gene copies in river water samples collected from the last location. Furthermore, pig-specific Bacteroidales 16S rRNA genetic marker was quantified by qPCR to determine the level of fecal pollution in the river water. Bivariate correlation analysis confirmed that the total relative abundance of the six TRGs was significantly correlated with the level of swine feces in the aquatic environment (R² = 0.63, P < 0.05), suggesting that swine feces mainly contributed to the spread of TRGs in the river water.

Supplemental materials are available for this article. Go to the publisher's online edition of Journal of Environmental Science and Health, Part A to view the free supplemental file.     

Insight into the interaction between trimethoprim and soluble microbial products produced from biological wastewater treatment processes

Soluble microbial products (SMPs),dissolved organic matter excreted by activated sludge,can interact with antibiotics in wastewater and natural water bodies.Interactions between SMPs and antibiotics can influence antibiotic migration,transformation,and toxicity but the mechanisms involved in such interactions are not fully understood.In this study,integrated spectroscopy approaches were used to investigate the mechanisms involved in interactions between SMPs and a representative antibiotic,trime...     

Occurrence, spatial distribution and ecological risks of antibiotics in soil in urban agglomeration

Antibiotics in soil environment are regarded as emerging pollutants and have introduced increasing risks to soil ecosystem and human health in rapid urbanization areas. Identifying the occurrence and spatial variability of antibiotics in soils is an urgent issue in sustaining soil security. In this study, antibiotics in soils were investigated and analyzed in Beijing-Tianjin-Hebei urban agglomeration. The occurrence, spatial distribution, and related affecting factors of antibiotics in soils were identified and ecological risks of antibiotics in soil environment were assessed. Results showed that (1) The mean concentration of soil antibiotics in Beijing-Tianjin-Hebei urban agglomeration was 21.79 µg/kg. Land use substantially affected the occurrence and concentration of antibiotics in soils. Concentrations of antibiotics in cropland and orchard soils were 2-3 times higher than the other land use types. (2) The concentrations of antibiotics in soils in Beijing-Tianjin-Hebei urban agglomeration presented a spatial pattern of high values in southeast, and low values in northwest. Spatial variability of antibiotics in soils was closely related to the application of organic fertilizer and wastewater irrigation as well as topographical features. Furthermore, soil properties and land management policy had substantial influences on soil antibiotics, and soil heavy metals may aggravate the accumulation of antibiotics in soils. (3) Ecological risks assessment of antibiotics in soils demonstrated that erythromycin (ERY), sulfamethoxazole (SMX), and doxycycline (DOX) may introduce high risks to soil ecosystem health, and more attention should be paid to the areas with intensive human activities that had potential high risk to soil ecosystem health. This study suggests that scientific land and soil management should be considered to prevent soil antibiotic pollution and sustain soil security in urban agglomeration.     

Stimulants and donors promote megaplasmid pND6-2 horizontal gene transfer in activated sludge

The activated sludge process is characterized by high microbial density and diversity, both of which facilitate antibiotic resistance gene transfer. Many studies have suggested that antibiotic and non-antibiotic drugs at sub-inhibitory concentrations are major inducers of conjugative gene transfer. The self-transmissible plasmid pND6-2 is one of the endogenous plasmids harbored in Pseudomonas putida ND6, which can trigger the transfer of another co-occurring naphthalene-degrading plasmid pND6-1. Therefore, to illustrate the potential influence of stimulants on conjugative transfer of pND6-2, we evaluated the effects of four antibiotics (ampicillin, gentamycin, kanamycin, and tetracycline) and naphthalene, on the conjugal transfer efficiency of pND6-2 by filter-mating experiment. Our findings demonstrated that all stimulants within an optimal dose promoted conjugative transfer of pND6-2 from Pseudomonas putida GKND6 to P. putida KT2440, with tetracycline being the most effective (100 µg/L and 10 µg/L), as it enhanced pND6-2-mediated intra-genera transfer by approximately one hundred-fold. Subsequently, seven AS reactors were constructed with the addition of donors and different stimulants to further elucidate the conjugative behavior of pND6-2 in natural environment. The stimulants positively affected the conjugal process of pND6-2, while donors reshaped the host abundance in the sludge. This was likely because stimulant addition enhanced the expression levels of conjugation transfer-related genes. Furthermore, Blastocatella and Chitinimonas were identified as the potential receptors of plasmid pND6-2, which was not affected by donor types. These findings demonstrate the positive role of sub-inhibitory stimulant treatment on pND6-2 conjugal transfer and the function of donors in re-shaping the host spectrum of pND6-2.     

Decoding and quantitative detection of antibiotics by a luminescent mixed-lanthanide-organic framework

● A series of mixed-LOFs and portable LOF-fibers were synthesized. ● LOF-S3 was selected as a luminescent sensor for antibiotics. ● Mixed-LOF was capable of decoding antibiotics by emission intensity ratios. ● Linear relationship between antibiotic concentration and I545nm/I618nm was observed. Due to the potential risk of antibiotics to the environment, the development of inexpensive, simple, and reliable antibiotic detection methods is significant but also faces challenges. In this work, several lanthanide-organic frameworks (LOFs), constructed from lanthanide ions (Eu³⁺ and/or Tb³⁺) and 1,3,5-benzene-tricarboxylic acid (BTC), were synthesized by solvothermal method. LOF-S3 with comparable emission peaks of ⁵D₄ → ⁷F₅ (Tb³⁺, 545 nm) and ⁵D₀ → ⁷F₂ (Eu³⁺, 618 nm) was selected as a luminescent sensor. In this system, the highly efficient energy transferred from the organic linker to lanthanide ions and from Tb³⁺ to Eu³⁺ occurs. LOF-S3 sensor was capable of decoding antibiotics by distinguishable emission intensity ratios. Therefore, a two-dimensional decoded map of antibiotics was established. The linear relationship between antibiotic concentration and emission intensity ratio indicated the quantitative determination of antibiotics was feasible. As a typical analyte, the response mechanism of nalidixic acid (NA) was investigated in detail. The competition of NA and BTC for UV light absorption, as well as the binding propensity of NA and Tb, affected the organic linkers-to-lanthanide ions and Tb-to-Eu energy transfer, resulting in the change of fluorescence intensity ratio. The self-calibrating mixed-LOF sensor overcame the uncontrollable errors of the traditional absolute emission intensity method and generated stable luminescent signals in multiple cycles. Furthermore, the integration of LOF-S3 with polymer fibers enabled the formation of a LOF-polymer fibrous composite with fluorescence detection capability, which is a promising portable sensor for practical applications.     

水环境中抗生素的污染现状及其去除方法研究进展

抗生素是用于防治人类和动物病菌性疾病,以及促进动物生长的一大类化学品.基于目前国内外大量使用抗生素的情况,本文针对抗生素对环境水体造成的污染,从环境水体中抗生素的来源入手,分析了抗生素在环境水体中的残留与污染水平.并讨论了目前国内外抗生素去除的研究情况,主要对常规处理技术、化学氧化、吸附3种手段进行了分析,最后对抗生素...