Sub-lethal concentration of sulfamethoxazole affects the growth performance of milkfish (Chanos chanos), the microbial composition of antibiotic-resistant bacteria and the prevalence of sulfonamide-resistance genes in mariculture. - Related Documents




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718701.0000Sub-lethal concentration of sulfamethoxazole affects the growth performance of milkfish (Chanos chanos), the microbial composition of antibiotic-resistant bacteria and the prevalence of sulfonamide-resistance genes in mariculture. To investigate the impacts of sub-lethal concentrations of antibiotic agents in mariculture, culturable approach and DNA based detection were employed to isolate and analyse resistant bacteria and resistant genes in this study. Milkfish (Chanos chanos), the target rearing animal was exposed to sulfamethoxazole (SMX; 2 mg/L) for 8 weeks and resulted in reduced survival rate and weight gain to 61.9 % and 28.4 %, respectively compared to control milkfish (p < 0.001). The composition of SMX-resistant bacteria isolated from the culture water and the gastrointestinal tracts of milkfish underwent changes in response to SMX treatment with a reduced diversity. The prevalence of SMX resistant genes sul in bacterial isolates was elevated from 2.8 % of control to 100 % of SMX-administrated water. Exposure to SMX at a sub-lethal dosage enhanced the prevalence of resistance genes sul1 and sul2 in resistant bacteria, thus implying high frequency of resistance dissemination in the marine environment and surrounding ecosystems.202235939929
779510.9997Factors influencing the removal of antibiotic-resistant bacteria and antibiotic resistance genes by the electrokinetic treatment. The performance of the electrokinetic remediation process on the removal of antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) was evaluated with different influencing factors. With chlortetracycline (CTC), oxytetracycline (OTC), and tetracycline (TC) as template chemicals, the removal of both ARB and ARGs was enhanced with the increase of voltage gradient (0.4-1.2 V cm(-1)) and prolonged reaction time (3-14 d). The greatest removal (26.01-31.48% for ARB, 37.93-83.10% for ARGs) was obtained applying a voltage of 1.2 V cm(-1), leading to the highest electrical consumption. The effect of polarity reversal intervals on the inactivation ratio of ARB followed the order of 0 h (66.06-80.00%) > 12 h (17.07-24.75%) > 24 h (10.44-13.93%). Lower pH, higher current density, and more evenly-distributed voltage drop was observed with a polarity reversal interval of 12 h compared with that of 24 h, leading to more efficient electrochemical reactions in soil. Compared with sul genes, tet genes were more vulnerable to be attacked in an electric field. It was mainly attributed to the lower abundance of tet genes (except tetM) and the varied effects of electrokinetic remediation process on different ARGs. Moreover, a relatively less removal ratio of tetC and tetG was obtained mainly due to the mechanism of the efflux pump upregulation. Both tet and sul genes were positively correlated with TC-resistant bacteria. The efflux pump genes like tetG and the cellular protection genes like tetM showed different correlations with ARB. This study enhances the current understanding on the removal strategies of ARB and ARGs, and it provides important parameters for their destruction by the electrokinetic treatment.201829807293
779420.9996Fate of antibiotic resistant bacteria and genes during wastewater chlorination: implication for antibiotic resistance control. This study investigated fates of nine antibiotic-resistant bacteria as well as two series of antibiotic resistance genes in wastewater treated by various doses of chlorine (0, 15, 30, 60, 150 and 300 mg Cl2 min/L). The results indicated that chlorination was effective in inactivating antibiotic-resistant bacteria. Most bacteria were inactivated completely at the lowest dose (15 mg Cl2 min/L). By comparison, sulfadiazine- and erythromycin-resistant bacteria exhibited tolerance to low chlorine dose (up to 60 mg Cl2 min/L). However, quantitative real-time PCRs revealed that chlorination decreased limited erythromycin or tetracycline resistance genes, with the removal levels of overall erythromycin and tetracycline resistance genes at 0.42 ± 0.12 log and 0.10 ± 0.02 log, respectively. About 40% of erythromycin-resistance genes and 80% of tetracycline resistance genes could not be removed by chlorination. Chlorination was considered not effective in controlling antimicrobial resistance. More concern needs to be paid to the potential risk of antibiotic resistance genes in the wastewater after chlorination.201525738838
720330.9996Removal of cephalexin and erythromycin antibiotics, and their resistance genes, by microalgae-bacteria consortium from wastewater treatment plant secondary effluents. Antibiotics have become a concern in the aquatic environments owing to the potential development of bacterial resistances. Thus, this study evaluated the removal of cephalexin (CEP) and erythromycin (ERY) from a local wastewater treatment plant (WWTP) effluent, mediated by microalgae-bacteria consortium. Likewise, the removal of correlated antibiotics resistance genes bla(TEM) and ermB was also assessed. The incubation results showed that the added concentrations of selected antibiotics did not restrain the consortium growth. Moreover, CEP and ERY were almost completely removed after the cultivation period, reaching total removals of 96.54% and 92.38%, respectively. The symbiotic interaction between microalgae and bacteria plays a role in the kinetics removal of CEP and ERY. The abundance of bla(TEM) and ermB was reduced by 0.56 and 1.75 logs, respectively. Lastly, our results suggest that technology based on natural microalgae-bacteria consortium could be a potential alternative to improve the quality of WWTP effluents.202134268682
800540.9996Deciphering the fate of antibiotic resistance genes in norfloxacin wastewater treated by a bio-electro-Fenton system. The misuse of antibiotics has increased the prevalence of antibiotic resistance genes (ARGs), considered a class of critical environmental contaminants due to their ubiquitous and persistent nature. Previous studies reported the potentiality of bio-electro-Fenton processes for antibiotic removal and ARGs control. However, the production and fate of ARGs in bio-electro-Fenton processes triggered by microbial fuel cells are rare. In this study, the norfloxacin (NFLX) average residual concentrations within two days were 2.02, 6.07 and 14.84 mg/L, and the average removal efficiency of NFLX was 79.8 %, 69.6 % and 62.9 % at the initial antibiotic concentrations of 10, 20 and 40 mg/L, respectively. The most prevalent resistance gene type in all processes was the fluoroquinolone antibiotic gene. Furthermore, Proteobacteria was the dominant ARG-carrying bacteria. Overall, this study can provide theoretical support for the efficient treatment of high antibiotics-contained wastewater by bio-electro-Fenton systems to better control ARGs from the perspective of ecological security.202236252757
352250.9996Effect of trace tetracycline concentrations on the structure of a microbial community and the development of tetracycline resistance genes in sequencing batch reactors. The objective of this study was to investigate effects of different concentrations of tetracycline (TC) on the microbial community and development of tetracycline resistance genes (TRGs) of sequencing batch reactors (SBRs). Polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) analysis of 16S rRNA and real-time fluorescence quantitative polymerase chain reaction (RT-qPCR) were used to detect the structural changes of the microbial community and the variations of eight TC resistance genes tet(A), tet(B), tet(C), tet(E), tet(M), tet(O), tet(S) and tet(X), respectively. The results indicated that, trace TC could substantially change the structure of the microbial community. Bacteria which could not adapt to environment with TC were gradually replaced by those adapting to tetracycline. Shannon's diversity index (H) and Simpson's index (D) reached maximum values when the concentration of TC was 1 μg L(-1). The resistance genes in the activated sludge proliferated under the pressure of trace TC.201324140945
800360.9996Dynamics of antibiotic resistance agents during sludge alkalinization treatment. This study aimed to assess the removal of antimicrobial resistance agents (antibiotics, antibiotic-resistant bacteria - ARB, and antimicrobial resistance genes - ARGs) from aerobic and anaerobic sludges treated with quicklime (chemical alkalinization). Different mixing ratios (25%, 35%, and 45%) and contact times (2 h and 72 h) were evaluated. The findings revealed that anaerobic sludge responded more effectively to alkaline treatment, achieving better removal rates of antibiotics, ARB, and ARGs compared to aerobic sludge. The 45% lime treatment yielded the highest antibiotic removal rates, with average reductions of 19% in aerobic sludge and 28% in anaerobic sludge. The 35% lime treatment was the most effective in reducing ARGs across both types of sludge (average removal of 2 logs). The 25% lime treatment proved most efficient for removing ARB, with average reductions of 4 logs (aerobic) and 5 logs (anaerobic). The contact time between the sludge and quicklime also influenced the removal of resistance agents. An increase in the proportion of antibiotics and the absolute concentration of ARB and ARGs was observed after 72 h compared to the samples analyzed after 2 h of contact. This increase was more pronounced in aerobic sludge samples treated with 35% and 45% lime. Despite the overall reduction, none of the monitored resistant genes or bacteria were completely eradicated in both sludge samples, raising concerns about their potential dissemination into the environment.202439414064
718970.9995Comparative effects of different antibiotics on antibiotic resistance during swine manure composting. This study explored commonly-used antibiotics (lincomycin, chlorotetracycline, sulfamethoxazole, and ciprofloxacin) and their collective effects on antibiotic resistance during composting. In the first 7 days, ciprofloxacin showed the greatest influence on the physicochemical factors among the studied antibiotics; the removal of antibiotic resistance genes (ARGs) in the multiple-antibiotic treatment was significantly less than single-antibiotic treatments; especially, the largest removal of ribosomal protection genes (tetW and tetO) occurred in single ciprofloxacin treatment. In the end of composting, similar removal ratio (29.71-99.79%) of ARGs was achieved in different treatments (p greater than 0.05); Chloroflexi became the main phylum and it was closely associated with ARGs removal based on the network analysis. Potential host bacteria of ARGs varied with different antibiotics; in particular, the presence of multiple antibiotics increased potential host bacteria of ermA, sul1 and tetO. Above all, collective effects of different antibiotics led to the enrichment of antibiotic resistance in the composting.202032712514
719180.9995The impact of antimicrobials on the efficiency of methane fermentation of sewage sludge, changes in microbial biodiversity and the spread of antibiotic resistance. The study was designed to simultaneously evaluate the influence of high doses (512-1024 µg/g) the most commonly prescribed antimicrobials on the efficiency of anaerobic digestion of sewage sludge, qualitative and quantitative changes in microbial consortia responsible for the fermentation process, the presence of methanogenic microorganisms, and the fate of antibiotic resistance genes (ARGs). The efficiency of antibiotic degradation during anaerobic treatment was also determined. Metronidazole, amoxicillin and ciprofloxacin exerted the greatest effect on methane fermentation by decreasing its efficiency. Metronidazole, amoxicillin, cefuroxime and sulfamethoxazole were degraded in 100%, whereas ciprofloxacin and nalidixic acid were least susceptible to degradation. The most extensive changes in the structure of digestate microbiota were observed in sewage sludge exposed to metronidazole, where a decrease in the percentage of bacteria of the phylum Bacteroidetes led to an increase in the proportions of bacteria of the phyla Firmicutes and Proteobacteria. The results of the analysis examining changes in the concentration of the functional methanogen gene (mcrA) did not reflect the actual efficiency of methane fermentation. In sewage sludge exposed to antimicrobials, a significant increase was noted in the concentrations of β-lactam, tetracycline and fluoroquinolone ARGs and integrase genes, but selective pressure was not specific to the corresponding ARGs.202133831706
718290.9995Effects of UV disinfection on phenotypes and genotypes of antibiotic-resistant bacteria in secondary effluent from a municipal wastewater treatment plant. To elucidate the effects of UV disinfection on antibiotic resistance in biologically-treated wastewater, we investigated the antibiotic resistance profiles, species of cultivable heterotrophic bacteria, and antibiotic-resistance genes (ARGs) in antibiotic-resistant bacteria before and after treatment. UV disinfection greatly changed the bacterial community structure and the antibiotic resistance in wastewater. The antibiotic resistance in wastewater samples was strongly associated with the bacterial community. The proportions of Gram-positive bacteria gradually increased with increasing UV fluence. The proportions of bacteria resistant to cephalexin, penicillin, and vancomycin all greatly decreased after UV treatment in both sampling events (July 2018 and January 2019), and those for bacteria resistant to ofloxacin, ciprofloxacin, and sulfadiazine increased, resulting from the alternative antibiotic resistance profiles among different genera. UV disinfection induced the selection of multi-antibiotic resistant (MAR) bacteria. For example, the MAR indices of Aeromonas, the dominant genus during the treatments, were significantly increased after UV irradiation (P < 0.05). The MAR index was also markedly increased (P < 0.05) at a fluence of 5 mJ/cm(2) in both events. In UV10 treatment, the bacterial community structure was greatly changed. The genera with relatively low MAR indices replaced that with high MAR indices, and became the dominant genera. As a result, the MAR indices of treated samples showed a decreased trend after 10 mJ/cm(2) UV irradiation. The detection frequencies of ARGs located on the chromosome varied mainly due to the evolution of the microbial community. The occurrence of ARGs (tetA, tetC, tetM, tetW, tetX, and sul1) located on plasmid DNA decreased after UV disinfection, and the average detection frequencies of tet and sul genes decreased by 15% and 6%, respectively (P < 0.05). Generally speaking, the effect of UV disinfection on the enrichment of antibiotic resistance is limited in this study, and horizontal gene transfer via the plasmids in surviving bacteria might be impaired due to the decreased abundance of ARGs on the plasmids.201930991178
7961100.9995Effect of tetracycline on ammonia and carbon removal by the facultative bacteria in the anaerobic digester of a sewage treatment plant. This study was conducted to see the effect of tetracycline on nitrogen assimilation and carbon removal in an anaerobic digester of a sewage plant. Samples of sewage were collected from an anaerobic digester sludge. Consortium of nitrogen assimilating bacteria were isolated from the sample and its ability to assimilate ammonia at different concentrations of tetracycline was measured along with carbon removal. The results indicate that while high concentrations of tetracycline of more than 100 mg/L delayed the growth of the bacteria, the resistant bacteria grew after a lag period and the removal of nitrogen and carbon was unaffected even at the highest tetracycline concentration of 250 mg/L tested in this study.201830025323
7793110.9995Treatment of pharmaceutical wastewater by ionizing radiation: Removal of antibiotics, antimicrobial resistance genes and antimicrobial activity. In present study, the treatment of real pharmaceutical wastewater from an erythromycin (ERY) production factory by gamma irradiation was investigated. Results showed that a variety of antimicrobial resistance genes (ARGs), involving MLSB, tet, bla, multidrug, sul, MGEs and van genes and plentiful 9 bacterial phyla were identified in the raw wastewater. In addition to ERY, sulfamethoxazole (SMX) and tetracycline (TC) were also identified with the concentration of 3 order of magnitude lower than ERY. Results showed that the abatement of ARGs and antibiotics was much higher than that of antimicrobial activity and COD. With the absorbed dose of 50 kGy, the removal percentage of ARGs, ERY, antimicrobial activity and COD was 96.5-99.8%, 90.0%, 47.8% and 10.3%, respectively. The culturable bacteria were abated fast and completely at 5.0 kGy during gamma irradiation. The genus Pseudomonas was predominant in raw wastewater (56.7%) and its relative abundance decreased after gamma irradiation, to 1.3% at 50 kGy. With addition of peroxymonosulfate (PMS, 50 mM), the antimicrobial activity disappeared completely and ERY removal reached as high as 99.2% at the lower absorbed dose of 25 kGy. Ionizing radiation-coupled technique is a potential option to treat pharmaceutical wastewater for reduction of antibiotics, ARGs and antimicrobial activity.202134088196
3521120.9995Indirect evidence of transposon-mediated selection of antibiotic resistance genes in aquatic systems at low-level oxytetracycline exposures. Subinhibitory levels of antibiotics can promote the development of antibiotic resistance in bacteria. However, it is unclear whether antibiotic concentrations released into aquatic systems exert adequate pressure to select populations with resistance traits. To examine this issue, 15 mesocosms containing pristine surface water were treated with oxytetracycline (OTC) for 56 days at five levels (0, 5, 20, 50, and 250 microg L(-1)), and six tetracycline-resistance genes (tet(B), tet(L), tet(M), ted(O), tet(Q), and tet(W)), the sum of those genes (tet(R)), "total" 16S-rRNA genes, and transposons (Tn916 and Tn 1545) were monitored using real-time PCR. Absolute water-column resistance-gene abundances did not change at any OTC exposure. However, an increase was observed in the ratio of tet(R) to 16S-rRNA genes in the 250 microg L(-1) OTC units, and an increase in the selection rate of Tc(r) genes (relative to 16S-rRNA genes) was seen when OTC levels were at 20 microg L(-1). Furthermore, tet(M) and Tn916/1545 gene abundances correlated among all treatments (r2 = 0.701, p = 0.05), and there were similar selection patterns of tetR and Tn916/1545 genes relative to the OTC level, suggesting a possible mechanism for retention of specific resistance genes within the systems.200818754392
8045130.9995Correlation among extracellular polymeric substances, tetracycline resistant bacteria and tetracycline resistance genes under trace tetracycline. Antibiotic resistance occurrences and proliferation in activated sludge have attracted more and more attention nowadays. However, the role which extracellular polymeric substance (EPS) plays on the antibiotic resistance is not clear. The changes and correlation among EPS, tetracycline (TC) resistant bacteria (TRB) and TC resistance genes (TRGs) of sequencing batch reactors (SBRs) were investigated. Performance of SBR without TC was compared with two other SBRs to which different amounts of TC were added. Total average EPS contents were found to increase significantly from 66 mg g−1 VSS to 181 mg g−1 VSS as the TC concentrations increased from 0 to 100 μg L−1. As the EPS content increased, TRB in sludge of the three SBRs increased significantly from 105 to 106 colony forming unit mL−1 after being exposed to TC. In addition, the concentrations of three groups of TRGs (copies mL−1) were determined by real-time fluorescence quantitative polymerase chain reaction and followed the order: efflux pump genes > ribosome protected genes > degradation enzyme genes. The numbers of TRGs in the idle stage were larger than those in the aeration sludge. Correlation coefficients (R2) between EPS and TRB in sludge were 0.823 (p < 0.01) while the correlation between EPS and total TRGs was poor (R2 = 0.463, p > 0.05). But it showed the same tendency that EPS and TRGs in sludge increased with the increasing of TC.201425461932
8018140.9995Analysis for microbial denitrification and antibiotic resistance during anaerobic digestion of cattle manure containing antibiotic. This study investigated the effects of tylosin (0, 10, and 100 mg/kg dry weight) on the denitrification genes and microbial community during the anaerobic digestion of cattle manure. N(2) emissions were reduced and N(2)O emissions were increased by 10 mg/kg tylosin. Adding 100 mg/kg tylosin increased the emission of both N(2)O and N(2). The different responses of denitrifying bacteria and genes to tylosin may have been due to the presence of antibiotic resistance genes (ARGs). Network analysis indicated that denitrification genes and ARGs had the same potential host bacteria. intI1 was more important for the horizontal transfer of denitrification genes and ARGs during anaerobic digestion than intI2. The anaerobic digestion of manure containing tylosin may increase nitrogen losses and the associated ecological risk.201931326686
7193150.9995Plasmid-mediated transfer of antibiotic resistance genes and biofilm formation in a simulated drinking water distribution system under chlorine pressure. The effects of disinfectants and plasmid-based antibiotic resistance genes (ARGs) on the growth of microorganisms and the plasmid-mediated transfer of ARGs in the water and biofilm of the drinking water distribution system under simulated conditions were explored. The heterotrophic plate count of the water in reactors with 0.1 mg/L NaClO and NH(2)Cl was higher than in the control groups. There was no similar phenomenon in biofilm. In the water of reactors containing NaClO, the aphA and bla genes were lower than in the antibiotic resistant bacteria group, while both genes were higher in the water of reactors with NH(2)Cl than in the control group. Chloramine may promote the transfer of ARGs in the water phase. Both genes in the biofilm of the reactors containing chlorine were lower than the control group. Correlation analysis between ARGs and water quality parameters revealed that the copy numbers of the aphA gene were significantly positively correlated with the copy numbers of the bla gene in water and significantly negatively correlated in biofilm (p < 0.05). The results of the sequencing assay showed that bacteria in the biofilm, in the presence of disinfectant, were primarily Gram-negative. 1.0 mg/L chlorine decreased the diversity of the community in the biofilm. The relative abundance of some bacteria that may undergo transfer increased in the biofilm of the reactor containing 0.1 mg/L chlorine.202539617560
7200160.9995Plant Growth, Antibiotic Uptake, and Prevalence of Antibiotic Resistance in an Endophytic System of Pakchoi under Antibiotic Exposure. Antibiotic contamination in agroecosystems may cause serious problems, such as the proliferation of various antibiotic resistant bacteria and the spreading of antibiotic resistance genes (ARGs) in the environment or even to human beings. However, it is unclear whether environmental antibiotics, antibiotic resistant bacteria, and ARGs can directly enter into, or occur in, the endophytic systems of plants exposed to pollutants. In this study, a hydroponic experiment exposing pakchoi (Brassica chinensis L.) to tetracycline, cephalexin, and sulfamethoxazole at 50% minimum inhibitory concentration (MIC) levels and MIC levels, respectively, was conducted to explore plant growth, antibiotic uptake, and the development of antibiotic resistance in endophytic systems. The three antibiotics promoted pakchoi growth at 50% MIC values. Target antibiotics at concentrations ranging from 6.9 to 48.1 µg·kg(-1) were detected in the treated vegetables. Additionally, the rates of antibiotic-resistant endophytic bacteria to total cultivable endophytic bacteria significantly increased as the antibiotics accumulated in the plants. The detection and quantification of ARGs indicated that four types, tetX, bla(CTX-M), and sul1 and sul2, which correspond to tetracycline, cephalexin, and sulfamethoxazole resistance, respectively, were present in the pakchoi endophytic system and increased with the antibiotic concentrations. The results highlight a potential risk of the development and spread of antibiotic resistance in vegetable endophytic systems.201729099753
7846170.9995Removal of antibiotic resistance genes and inactivation of antibiotic-resistant bacteria by oxidative treatments. The persistence of antibiotics in the environment because of human activities, such as seafood cultivation, has attracted great attention as they can give rise to antibiotic resistance genes (ARGs) and antibiotic-resistant bacteria (ARB). In this study, we explored the inactivation and removal efficiencies of Escherichia coli SR1 and sul1 (plasmid-encoded ARGs), respectively, in their extracellular and intracellular forms (eARGs and iARGs) by three commonly used fishery oxidants, namely chlorine, bromine, and potassium permanganate (KMnO(4)), at the practical effective concentration range (0.5, 5, and 15 mg/L). Kinetics data were obtained using laboratory phosphate-buffered saline (PBS). Following the same fishery oxidation methods, the determined kinetics models were tested by studying the SR1 and sul1 disinfection efficiencies in (sterilized) pond water matrix. At concentrations of 5 and 15 mg/L, all three oxidants achieved sufficient cumulative integrated exposure (CT values) to completely inactivate SR1 and efficiently remove sul1 (up to 4.0-log). The oxidation methods were then applied to an unsterilized pond water matrix in order to study and evaluate the indigenous ARB and ARGs disinfection efficiencies in aquaculture, which reached 1.4-log and 1.0-log during treatment with fishery oxidants used in pond preparation at high concentrations before stocking (5-15 mg/L), respectively. A high chlorine concentration (15 mg/L) could efficiently remove ARGs (or iARGs) from pond water, and the iARG removal efficiency was higher than that of eARGs in pond water. The method and results of this study could aid in guiding future research and practical disinfection to control the spread of ARGs and ARB in aquaculture.202134030387
7784180.9995No evidential correlation between veterinary antibiotic degradation ability and resistance genes in microorganisms during the biodegradation of doxycycline. Biodegradation of antibiotic residues in the environment by microorganisms may lead to the generation of antibiotic resistance genes (ARGs), which are of great concern to human health. The aim of this study was to determine whether there is a relationship between the ability to degrade antibiotic doxycycline (DOX) and the development of resistance genes in microorganisms. We isolated and identified ten bacterial strains from a vegetable field that had received long-term manure application as fertilizer and were capable of surviving in a series of DOX concentrations (25, 50, 80, and 100mg/L). Our results showed no evidential correlation between DOX degradation ability and the development of resistance genes among the isolated microorganisms that had high DOX degradation capability (P > 0.05). This was based on the fact that Escherichia sp. and Candida sp. were the most efficient bacterial strains to degrade DOX (92.52% and 91.63%, respectively), but their tetracycline resistance genes showed a relatively low risk of antibiotic resistance in a 7-day experiment. Moreover, the tetM of the ribosomal protection protein genes carried by these two preponderant bacteria was five-fold higher than that carried by other isolates (P < 0.05). Pearson correlations between the C(t)/C(0) of DOX and tet resistance genes of three isolates, except for Escherichia sp. and Candida sp., showed remarkable negative correlations (P < 0.05), mainly because tetG markedly increased during the DOX degradation process. Our results concluded that the biodegradation of antibiotic residues may not necessarily lead to the development of ARGs in the environment. In addition, the two bacteria that we isolated, namely, Escherichia sp. and Candida sp., are potential candidates for the engineering of environmentally friendly bacteria.201828942279
7251190.9995Effects of tetracycline antibiotics in chicken manure on soil microbes and antibiotic resistance genes (ARGs). China is the world's largest livestock and poultry breeding country, but also the largest use of veterinary antibiotics. When a large amount of chicken manure is applied to the soil, it will cause the number of antibiotic residues and resistant bacteria to increase, which will bring about the pollution of antibiotic resistance genes (ARGs) in the soil, and then increase the risk of environmental pollution and human health. Field experiments were conducted to study the changes of soil tetracycline antibiotic residues, resistant bacteria and resistance genes treated with different types and dosage of chicken manure (no chicken manure, (CK), low fresh chicken manure treatment (300 kg·667 m(-2)), high fresh chicken manure treatment (600 kg·667 m(-2)), low decomposed chicken manure treatment (300 kg·667 m(-2)) and high decomposed chicken manure treatment (600 kg·667 m(-2))). After one-year application of chicken manure, content of soil organic matter increased by 1.0%-3.2% compared with the control. The activity of soil catalase significantly increased by 84.3-91.5%, 81.9-102.9% in fresh and decomposed chicken manure treatments compared with the control, respectively. The amount of soil resistant bacteria under the same treatment was in the order of Anti-OTC > Anti-TC > Anti-CTC. After one-year application of chicken manure, the total tetracycline amount in the soil was increased by 168.5-217.9% compared with the control. The amount of antibiotic residue in soil treated with fresh chicken manure was 3.0-9.1% higher than that treated with decomposed chicken manure. The abundance of ARGs in the soil was in the order of that treated with high fresh chicken manure > low fresh chicken manure > high decomposed chicken manure > low decomposed chicken manure. The risk of tetracycline antibiotics to soil ecological environment may be greatly reduced after chicken manure decomposed.202234114159