Antibiotic Resistance Genes In Water Research Articles

Transmission mechanism of antibiotic resistance genes and their differences between water and sediment in the Weihe River Basin

Antibiotic resistance genes (ARGs) are emerging microbial pollutants that are regulated by many factors and pose potential threats to aquatic environments. In this study, we used network analysis, correlation analysis, and constructed models based on metagenomic sequencing results to explore the spatial patterns, impact mechanisms, transmission risks and differences in ARGs in the water and sediment of the Weihe River Basin. The findings revealed notable disparities in ARGs, mobile genetic elements (MGEs), and bacterial communities. In the sediment, the abundance of ARGs was considerably greater than that in water. Moreover, the percentage of ARGs shared by the two components reached a value of 85.8%. Through network analysis, it was determined that the presence of 16 MGEs and 20 bacterial phyla was strongly associated with ARGs (R2>0.7, P<0.05). The Mantel test showed that abiotic factors including DO, pH, nutrients, and heavy metals played important roles in the distribution of ARGs (P<0.05). A structural equation model revealed that the key factors influencing the distribution of ARGs in water were bacterial diversity and environmental parameters (standardized effects of -0.730 and -0.667), and those in sediment were bacterial diversity and MGEs (standardized effects of -0.751 and 0.851). Neutral modeling indicated that deterministic processes played an important role in the assembly of ARGs in the water of the Weihe River Basin, and stochastic processes were dominant in the sediment. There was a highly significant positive linear correlation between ARGs and pathogens, and there was more complex co-occurrence in the water than in the sediment (R2>0.9, P<0.05), with stronger migration and transmission occurring. Exploring ARGs in large-scale watersheds is immensely important for elucidating their traits and transmission mechanisms and consequently paving the way for the formulation of efficient strategies to mitigate resistance threats.

Insight into the evolution of microbial communities and resistance genes induced by sucralose in partial nitrification system with triclosan pre-exposure

Sucralose (SUC), an artificial sweetener widely used in food, beverages and pharmaceuticals, is frequently detected in various environmental matrices. Triclosan (TCS) is commonly used as a disinfectant and often co-exists with SUC in sewage environments. This study investigated the effects of SUC (0.1–10 mg/L) on the transmission of intracellular and extracellular antibiotic resistance genes (ARGs) in the partial nitrification systems with and without TCS pre-exposure. The reactors operated for 150 days, and SUC did not affect ammonia oxidation performance, while TCS led to the maintenance of partial nitrification. The types and abundances of extracellular ARGs in sludge and free ARGs in water increased significantly after TCS pre-exposure when faced SUC stress, which might be caused by a decrease in α-Helix/(β-Sheet + Random coil). SUC was more easily to enrich ARGs in partial nitrification systems with TCS pre-exposure, exacerbating the risk of ARGs transmission. The microbial community showed stronger relationships to cope with the direct stress of SUC, and the functional bacteria (Thauera and Nitrosomonas) in TCS pre-exposure system might be potential hosts of ARGs. This study might provide insights for better understanding the fates of SUC in partial nitrification systems and the ecological risks in wastewater containing TCS and SUC. Environmental ImplicationSucralose (SUC) is often detected in the environment and considered as an emerging contaminant due to its soaring consumption and environmental persistence. Triclosan (TCS) is an antibacterial agent that often co-exists with SUC in personal care products and sewage environments. During 150 d, two partial nitrification reactors with and without TCS pre-exposure were established to study the effects of SUC on nitrification performance, antibiotic resistance genes (ARGs) and microbial communities. This study showed the refractory nature of SUC, and SUC led to the transmission of extracellular ARGs in partial nitrification system with TCS pre-exposure, exacerbating the risk of ARGs dissemination.

Purification of aquaculture wastewater by macrophytes and biofilm systems: Efficient removal of trace antibiotics and enrichment of antibiotic resistance genes

The purification performance of aquaculture wastewater and the risk of antibiotic resistance genes (ARGs) dissemination in wetlands dominated by macrophytes remain unclear. Here, the purification effects of different macrophytes and biofilm systems on real aquaculture wastewater were investigated, as well as the distribution and abundance of ARGs. Compared to the submerged macrophytes, artificial macrophytes exhibited higher removal rates of TOC (58.80 ± 5.04 %), TN (74.50 ± 2.50 %), and TP (77.33 ± 11.66 %), and achieved approximately 79.92 % removal of accumulated trace antibiotics in the surrounding water. Additionally, the biofilm microbial communities on the surface of artificial macrophytes exhibited higher microbial diversity with fewer antibiotic-resistant bacteria (ARB) enrichment from the surrounding water. The absolute abundance of ARGs (sul1, sul2, and intI1) in the mature biofilm to be one to two orders of magnitude higher than that in the water. Although biofilms could decrease ARGs in the surrounding water by enriching ARB, the intricate network structure of biofilms further facilitated the proliferation of ARB and the dissemination of ARGs in water. Network analysis suggested that Proteobacteria and Firmicutes phyla were dominant and potential carriers of ARGs, contributing 69.00 % and 16.70 %, respectively. Our findings highlight that macrophytes and biofilm systems have great performance on aquaculture wastewater purification, but with high risk of ARGs.

Simultaneous removal of antibiotic-resistant Escherichia coli and its resistance genes by dielectric barrier discharge plasma

As emerging contaminants, antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) have been widely detected in various aqueous environments. For antibiotic resistance to be inhibited in the environment, it is essential to control ARB and ARGs. In this study, dielectric barrier discharge (DBD) plasma was used to inactivate antibiotic resistant Escherichia coli (AR E. coli) and remove ARGs simultaneously. Within 15 s of plasma treatment, 108 CFU/mL of AR E. coli were inactivated by 97.9%. The rupture of the bacterial cell membrane and the increase of intracellular ROS are the main reasons for the rapid inactivation of bacteria. Intracellular ARGs (i-qnrB, i-blaCTX-M, i-sul2) and integron gene (i-int1) decreased by 2.01, 1.84, 2.40, and 2.73 log after 15 min of plasma treatment, respectively. In the first 5 min of discharge, extracellular ARGs (e-qnrB, e-blaCTX-M, e-sul2) and integron gene (e-int1) decreased by 1.99, 2.22, 2.66, and 2.80 log, respectively. The results of the ESR and quenching experiments demonstrated that ·OH and 1O2 played important roles in the removal of ARGs. This study shows that DBD plasma is an effective technique to control ARB and ARGs in waters.

Efficient peroxymonosulfate activation by magnetic MoS2@Fe3O4 for rapid degradation of free DNA bases and antibiotic resistance genes

Antibiotic resistance genes (ARGs) have become as emerging contaminant with great concerns worldwide due to their threats to human health. It is thus urgent to develop techniques to degrade ARGs in water. In this study, MoS2@Fe3O4 (MF) particles were fabricated and used to activate peroxymonosulfate (PMS) for the degradation of four types of free DNA bases (T, A, C, and G, major components of ARGs) and ARGs. We found that MF/PMS system could effectively degrade all four DNA bases (T within 10 min, A within 30 min, C within 5 min, and G within 5 min) in very short time. During the reaction process, MF could activate PMS to form the reactive radicals such as ·OH, SO4·−, O2·−, and 1O2, contributing to the degradation of DNA bases. Due to the low adsorption energy, high charge transfer, and great capability for PMS cleavage, MF exhibited excellent PMS adsorption and activation performances. MoS2 in MF could enhance the cycle of Fe(III)/Fe(II), improving the catalytic performance. Excellent catalytic performances of MF/PMS system were achieved in complex water matrix (including different solution pH, coexisting of anions and natural organic matter) as well as in real water samples (including tap water, river water, sea water, and sewage) especially under high salinity conditions due to the generation of Cl· radicals and HClO species. MF/PMS system could also efficiently degrade ARGs (chromosomal kanR and plasmid gmrA) and DNA extracted from antibiotic resistant bacteria (ARB) in super-short time. Moreover, complete disinfection of two types of model ARB (E. coli K-12 MG 1655 and E. coli S17–1) could also be achieved in MF/PMS system. The high degradation performances of MF/PMS system achieved in the reused experiments and the 14-day continuous flow reactor experiments indicated the stability of MF particles. Due to the magnetic property, it would be convenient to separate MF particles from water after use via using magnet, facilitating their reuse of MF and avoiding potential water contamination by catalysts. Overall, this study not only provided a deep insight on Fe/Mo-triggered PMS activation process, but also provided an effective and reliable approach for the treatment of DNA bases, ARGs, DNA, and ARB in water.

A Review of Antibiotics, Antibiotic Resistant Bacteria, and Resistance Genes in Aquaculture: Occurrence, Contamination, and Transmission.

Antibiotics are commonly used to prevent and control diseases in aquaculture. However, long-term/overuse of antibiotics not only leaves residues but results in the development of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs). Antibiotics, ARB, and ARGs are widespread in aquaculture ecosystems. However, their impacts and interaction mechanisms in biotic and abiotic media remain to be clarified. In this paper, we summarized the detection methods, present status, and transfer mechanisms of antibiotics, ARB, and ARGs in water, sediment, and aquaculture organisms. Currently, the dominant methods of detecting antibiotics, ARB, and ARGs are UPLC-MS/MS, 16S rRNA sequencing, and metagenomics, respectively. Tetracyclines, macrolides, fluoroquinolones, and sulfonamides are most frequently detected in aquaculture. Generally, antibiotic concentrations and ARG abundance in sediment are much higher than those in water. Yet, no obvious patterns in the category of antibiotics or ARB are present in organisms or the environment. The key mechanisms of resistance to antibiotics in bacteria include reducing the cell membrane permeability, enhancing antibiotic efflux, and structural changes in antibiotic target proteins. Moreover, horizontal transfer is a major pathway for ARGs transfer, including conjugation, transformation, transduction, and vesiculation. Identifying, quantifying, and summarizing the interactions and transmission mechanisms of antibiotics, ARGs, and ARB would provide useful information for future disease diagnosis and scientific management in aquaculture.

Removal of antibiotic resistant bacteria and plasmid-encoded antibiotic resistance genes in water by ozonation and electro-peroxone process

The electro-peroxone (EP) process is an electricity-based oxidation process enabled by electrochemically generating hydrogen peroxide (H2O2) from cathodic oxygen (O2) reduction during ozonation. In this study, the removal of antibiotic resistant bacteria (ARB) and plasmid-encoded antibiotic resistance genes (ARGs) during groundwater treatment by ozonation alone and the EP process was compared. Owing to the H2O2-promoted ozone (O3) conversion to hydroxyl radicals (•OH), higher •OH exposures, but lower O3 exposures were obtained during the EP process than ozonation alone. This opposite change of O3 and •OH exposures decreases the efficiency of ARB inactivation and ARG degradation moderately during the EP process compared with ozonation alone. These results suggest that regarding ARB inactivation and ARG degradation, the reduction of O3 exposures may not be fully counterbalanced by the rise of •OH exposures when changing ozonation to the EP process. However, due to the rise of •OH exposure, plasmid DNA was more effectively cleaved to shorter fragments during the EP process than ozonation alone, which may decrease the risks of natural transformation of ARGs. These findings highlight that the influence of the EP process on ARB and ARG inactivation needs to be considered when implementing this process in water treatment.

Influence of DNA from non-viable sources on the riverine water and biofilm microbiome, resistome, mobilome, and resistance gene host assignments

Shotgun metagenomic studies have revealed the diversity, relative abundance, and hosts of antibiotic resistance genes (ARGs) across environmental matrices. There is motivation to combine this method with viability-based techniques to better define ARG hazard. The objectives of this study were to evaluate the performance of different methods for extracellular DNA (eDNA) and putative “non-viable” cell DNA separation to understand the influence on ARG-host assignments. Paired water and biofilm samples were collected along a land use gradient. To study putative “viable-cell” DNA, samples were treated with propidium monoazide (i.e., PMA-DNA). To study eDNA, intracellular and extracellular DNA were separated. qPCR revealed differences in total 16S rRNA gene copies in water for filter vs. centrifuge-concentrated samples, but otherwise there were no differences in gene copy concentrations between DNA fractions. Next, metagenomic sequencing was performed on PMA-DNA and total DNA extracts revealing significant differences between the two for bacterial community structure and ARG profiles. Putative viable taxa containing pathogenic ARG hosts were identified in biofilm and water. Removing PMA-bound DNA improved N50 and assembly mapping compared to total DNA extracts. This study demonstrates the impact of different sample preparation methods on informing the hazard potential associated with riverine ARGs in water and biofilm.

Multi-omics methods reveal that putrescine and cadaverine cause different degrees of enrichment of high-risk resistomes and opportunistic pathogens in the water and sediment of the Yellow River

Contamination of antibiotic resistomes due to animal carcass decay has become a serious environmental concern. However, the relationship between main metabolite compounds of corpse decomposition (i.e., putrescine and cadaverine) and antibiotic resistomes remains unclear. To tackle this issue, the response of antibiotic resistance genes (ARGs) and microbiome in aquatic environment to excess putrescine, cadaverine and a mixture of both based on laboratory simulation experiment was investigated by high-throughput quantitative PCR and amplicon sequencing methods. Our results showed putrescine and cadaverine led to the increasing of TC (total carbon) and TN (total nitrogen) both in water and sediment. Under the exposure of putrescine and cadaverine, the total abundance of mobile genetic elements (MGEs) and most ARGs in water was higher than in sediment. In particular, putrescine and cadaverine caused significantly different decreases in alpha diversity of microbial community in water and sediment compared with the control group. Microbial community structures both in water and sediment were also significantly affected by cadaverine and putrescine. Furthermore, putrescine and cadaverine led to different degrees of increases of high-risk ARGs (like mecA) and opportunistic pathogens (like Delftia) in sediment, promoting the prevalence of antibiotic resistant bacteria. In conclusion, our findings revealed the influences of main metabolites of carcass decay on microbiome and resistomes, providing references for risk assessment and pollution management.

Profiles and natural drivers of antibiotic resistome in multiple environmental media in penguin-colonized area in Antarctica

Profiles and driving mechanisms of antibiotic resistome in the polar region are important for exploring the natural evolution of antibiotic resistance genes (ARGs). Here, we evaluated the profiles of antibiotic resistome in multiple media on Inexpressible Island, Terra Nova Bay, Antarctica. Average concentrations of ARGs in intracellular DNA (iARGs) among water (3.98 × 106 copies/L), soil (3.41 × 107 copies/kg), and penguin guano (7.04 × 107 copies/kg) were higher than those of ARGs in extracellular DNA (eARGs) among water (1.99 × 104 copies/L), soil (1.75 × 106 copies/kg), and penguin guano (8.02 × 106 copies/kg). It was indicated that the transmission of ARGs across different media occurs with around 78.1% of iARGs from soil and 86.7% of iARGs from penguins observed in water, and 80.7% of iARGs and 56.7% of eARGs from penguins found in soil. Annual inputs of ARGs from Adélie penguins on Inexpressible Island have increased since 1983. Bacitracin, multidrug, and aminoglycoside resistance genes were the main ARGs among water, soil, and penguin guano. Primary medium-risk ARGs associated with human pathogenic bacteria were multidrug resistance genes, and main low-risk ARGs associated with mobile genetic elements (MGEs) were aminoglycoside resistance genes. Antibiotic-resistant bacteria (ARB) from soil and penguins were more phylogenetically related to aquatic antibiotic-resistant mesophiles than aquatic antibiotic-resistant psychrophiles. MGEs, ARB, bacterial diversities, antibiotics, and metals could explain total ARGs between water and soil. Intracellular MGEs were the most significant in-situ driver of iARGs in water, reflecting that horizontal gene transfer could facilitate the spread of ARGs in water. Penguins were important ex-situ drivers of environmental antibiotic resistome, which was linked with risky ARGs between water and soil. These findings highlight the major roles of natural drivers (e.g., MGEs and penguins) in shaping environmental antibiotic resistome in polar areas, improving our understanding of the evolution of environmental microbiome.

Elimination and Redistribution of Intracellular and Extracellular Antibiotic Resistance Genes in Water and Wastewater Disinfection Processes: A Review

Antibiotic resistance genes (ARGs) have been identified as emerging contaminants in water and wastewater. Concerns have been raised of whether disinfection processes can effectively eliminate ARGs and thus mitigate their spread. Due to the different existing forms and dissemination pathways, intracellular ARGs (iARGs) and extracellular ARGs (eARGs) have different responses to disinfection processes. This review compares the elimination of iARGs and eARGs in representative disinfection processes applied at water and wastewater treatment plants, including treatment by chlorine, chloramine, chlorine dioxide, ozone, ultraviolet irradiation (UV), and combination of UV with chemicals. Meanwhile, the redistribution of ARGs upon disinfection processes is highlighted. Elimination efficiencies of ARGs generally follow the order: ozone > chlorine ≫ chlorine dioxide > chloramine. The elimination of naked eARGs could be up to 4-log higher than that of iARGs. Notably, these disinfectants and the resulting disinfection byproducts formed in disinfection process can select antibiotic resistant bacteria (ARB) and increase relative abundances of iARGs. Under practical disinfectant exposure, elevated abundances of eARGs may be observed. Low doses of chlorine and chloramine tend to enhance the transfer of ARGs from intracellular to extracellular forms. To selectively control ARGs and associated risks and meanwhile minimize the unintended consequences, the disinfection practice may warrant optimization.

The inactivation of antibiotic-resistant bacteria and the damage of antibiotic-resistant genes using an electrified carbon nanotube membrane-NaClO system

The inactivation of antibiotic-resistant bacteria (ARB) and damage of antibiotic resistance genes (ARGs) in aquatic environments have become major concerns worldwide in controlling the rapid spread of antibiotic resistance. In this study, an electrified carbon nanotube membrane (ECM) was combined with chlorine disinfection (denoted as ECM-NaClO system) to treat the sulphonamide resistance bacteria (HLS-6) and tetracycline resistance bacteria (TOP-10F) in water samples. The ECM-NaClO system effectively inactivated the HLS-6 and TOP-10F by damaging the cell membrane and increasing amounts of intracellular reactive oxygen species (ROS). In addition, the absolute abundances of the sulphonamide resistance gene (sul1) and tetracycline resistance gene (tetA) in the effluent decreased by 3.5 and 1.7 logs, respectively. Furthermore, the absolute abundance of mobile genetic elements (intI1) decreased by 4.1–4.7 logs. The ROS probe compound degradation and quenching experiments revealed that the •OH generated via the 2-electron oxygen reduction reaction played a dominant role in the damage of sul1 gene, while •O2– generated through the activation of NaClO was a key contributor to the damage of tetA gene. Hence, the ECM-NaClO system is a potential method to inactivate ARB and damage ARGs in water and sewage treatment plants.

Influence of chlorinated disinfection by-products on transmission of antibiotic resistance genes in biofilms and water of a simulated drinking water distribution system

The spread of antibiotic resistance genes (ARGs) caused by biofilm growth in drinking water distribution systems (DWDSs) poses a serious threat to human health. The influence of disinfection by-products (DBPs) on the distribution of ARGs and mobile genetic elements (MGEs) in different phases (biofilms and water) of DWDSs is unclear. In this study, the characteristics of microbial indices, trihalomethanes (THMs), haloacetic acids (HAAs), ARGs and MGEs in biofilms and effluents of simulated DWDS reactors were detected during 150 d of operation. During the mature biofilm periods of 90 d or 120 d, for both biofilms and effluents, seven categories of ARGs (except tetracycline) and MGEs were at their highest and lowest relative abundance in the entire operation cycle, respectively. The influence of DBPs on ARGs and MGEs in the DWDS was different in different phases. In effluents, DBPs showed a stronger relationship with ARGs compared with MGEs. THMs and HAAs had positive correlations with various ARGs, which indicated that DBPs affected the distribution of resistance genes. In biofilms, the influence of MGEs on ARGs was stronger than that of DBPs on ARGs. Thus, DBPs might be an important contributor to the enrichment and spread of ARGs in water.

Watershed urbanization enhances the enrichment of pathogenic bacteria and antibiotic resistance genes on microplastics in the water environment

Microplastics (MPs) serve as vectors for microorganisms and antibiotic resistance genes (ARGs) and contribute to the spread of pathogenic bacteria and ARGs across various environments. Patterns of microbial communities and ARGs in the biofilm on the surface of MPs, also termed as plastisphere, have become an issue of global concern. Although antibiotic resistome in the plastisphere has been detected, how watershed urbanization affects patterns of potential pathogens and ARGs in the microplastic biofilms is still unclear. Here, we compared the bacterial communities, the interaction between bacterial taxa, pathogenic bacteria, and ARGs between the plastisphere and their surrounding water, and revealed the extensive influence of urbanization on them. Our results showed that bacterial communities and interactions in the plastisphere differed from those in their surrounding water. Microplastics selectively enriched Bacteroidetes from water. In non-urbanized area, the abundance of Oxyphotobacteria was significantly (p < 0.05) higher in plastisphere than that in water, while α-Proteobacteria was significantly (p < 0.05) higher in plastisphere than those in water of urbanized area. Pathogenic bacteria, ARGs, and mobile genetic elements (MGEs) were significantly (p < 0.05) higher in the urbanized area than those in non-urbanized area. MPs selectively enriched ARG-carrying potential pathogens, i.e., Klebsiella pneumoniae and Enterobacter cloacae, and exhibited a distinct effect on the relative abundance of ARG and pathogens in water with different urbanization levels. We further found ARGs were significantly correlated to MGEs and pathogenic bacteria. These results suggested that MPs would promote the dissemination of ARGs among microbes including pathogenic bacteria, and urbanization would affect the impact of MPs on microbes, pathogens, and ARGs in water. A high level of urbanization could enhance the enrichment of pathogens and ARGs by MPs in aquatic systems and increase microbial risk in aquatic environments. Our findings highlighted the necessity of controlling the spread of ARGs among pathogens and the usage of plastic products in ecosystems of urban areas.

Metagenomic analysis reveals the diversity and distribution of antibiotic resistance genes in thermokarst lakes of the Yellow River Source Area

Thermokarst lakes form as the results of ice-rich permafrost thawing and act as important water resources in cold regions. However, the distributions of antibiotic resistance genes (ARGs) in thermokarst lakes are far less studied. Using metagenomic sequencing approach, we provided the first study to document ARGs in thermokarst lakes of the Yellow River Source Area on the Qinghai-Tibet Plateau (QTP). The results revealed that both sediment and water of the thermokarst lakes harbor diverse ARGs. Multidrug resistance genes were the most diverse, while rifamycin resistance genes were the most abundant with rpoB2 and rpoB genes having the highest proportion. Sediment samples contained more ARGs than water samples, but their composition differed between the two types of samples. However, the composition variations of sediment and water ARGs were closely correlated. The Sorensen dissimilarities of ARGs were controlled by strong turnover processes in sediment samples, and by turnover and nestedness in water samples. High contributions of nestedness were found between sediment and water samples. Moreover, ARGs in water had more significant relationships with environmental variables than that in sediment. Given the role of thermokarst lakes as important water resources in permafrost landscape, as well as intensifying influences of climate change and anthropogenetic activities, thermokarst lakes could bring potential ARG risks, warranting further investigation and evaluation.

Photochemical degradation pathways of cell-free antibiotic resistance genes in water under simulated sunlight irradiation: Experimental and quantum chemical studies.

The presence of antibiotic resistance genes (ARGs) in the environment poses a threat to human health and therefore their environmental behavior needs to be studied urgently. A systematic study was conducted on the photodegradation pathways of the cell-free tetracycline resistance gene (Tc-ARG) under simulated sunlight irradiation. The results showed that Tc-ARG can undergo direct photodegradation, which significantly reduces its horizontal transfer efficiency. Suwannee River fulvic acid (SRFA) promoted the photodegradation of Tc-ARG and further inhibited its horizontal transfer by generating reactive intermediates. The photodegradation of Tc-ARG was attributed to degradation of the four bases (G, C, A, T) and the deoxyribose group. Quantum chemical calculations showed that the four bases could be oxidized by the hydroxyl radical (HO) through addition and H-abstraction reactions. The main oxidative product 8-oxo-dG was detected. This product was generated through the addition reaction of G-C with HO, subsequent to dissolved oxygen initiated H-abstraction and H2O catalyzed H-transfer reactions. The predicted maximum photodegradation rates of Tc-ARG in the Yellow River estuary were 0.524, 0.937, and 0.336 h-1 in fresh water, estuary water, and seawater, respectively. This study furthermore revealed the microscopic photodegradation pathways and obtained essential degradation parameters of Tc-ARG in sunlit surface water.

Occurrence and distribution of antibiotics and antibiotic resistance genes in water of Liaohe River Basin, China

Surface water environment is an important repository of antibiotics and antibiotic resistance genes (ARGs). It is of great significance to study the occurrence and distribution of antibiotics and ARGs in surface water environment. In this study, the Liaohe River Basin, China was taken as the study area, and the concentrations of antibiotics and ARGs in water were investigated by HPLC-MS/MS and HT-qPCR. The results showed that a total of 53 antibiotics of 6 types were detected in water, and the pollution level was at ND~331.64 ng/L, where PCG was the highest. Totally 164 ARGs and 10 mobile genetic elements (MGEs) were detected in the water, and the absolute abundances were at 2.18 × 104~3.95 × 107 copies/L and 1.82 × 105–3.78 × 107 copies/L, respectively. The multidrug and aminoglycoside were the dominant ARG types. Amoxicillin, erythromycin, anhydroerythromycin and ofloxacin posed certain ecological risks for sensitive aquatic organisms. In spatial distribution, the pollution of antibiotics and ARGs in the Daliao River system was higher than that in the Liaohe River system. There was a significant positive correlation between total concentrations of antibiotics and total relative abundance of ARGs (r = 0.66, p < 0.05). The co-occurrence of multiple antibiotics promoted the pollution and spread of ARGs. In addition, the total relative abundance of MGEs and ARGs showed a significant positive correlation (r = 0.946, p < 0.01), and MGEs played an important role in the occurrence and evolution of ARGs in water.

Editorial: Antibiotics and Antibiotic Resistance Genes in Waters: Pollution, Risks, and Control

Editorial: Antibiotics and Antibiotic Resistance Genes in Waters: Pollution, Risks, and Control

Gene resistance profile and multidrug-resistant bacteria isolated from a stream in midwestern Brazil

Freshwater environments are susceptible to contamination by antibiotics, antibiotic resistant bacteria (ABRs) and antibiotic resistance genes (ARGs). Contaminants come from diffuse and point sources, such as surface runoff, sewage and leaching. The increase in the prevalence of ARBs and ARGs is of global importance, having a direct impact on public health, due to the increase in resistant pathogenic strains and the lack of effective antibiotic therapy. In this context, the general objective of this study was to verify the prevalence of ARBs and ARGs in water and sediment samples, evaluating the microbiological quality of the João Leite stream. Bacterial cultures (bacterial counting, multi-tube analysis, bacterial isolation, identification by bacterial phenotype and antibiogram) and qPCR test to identify ARGs were performed. The microbiological quality of the water is not in accordance with Brazil current legislation, being unsuitable even for primary contact recreation (bath and leisure), having a large amount of coliforms and E. coli. The most isolated phylum was Proteobacteria and Firmicutes. ABRs were 62.64% resistant to CFZ (Cefazolin), 54.97% resistant to AMP (ampicillin), 47.56% resistant to CLI (clindamycin) and 45.05% resistant to AMC (amoxicillin/clavulanic acid). Multidrug resistance was found in 31.79% of the isolates. Were detected ABRs in all water and sediment samples in this study, with the presence of some antibiotic resistance gene. ARGs were more found in water samples, with genes encoding resistance to β-lactams, macrolides, quinolones, fluoroquinolone, tetracyclines and sulfonamides being detected. Statistically significant correlations between ARBs and ARGs were detected, it is suggested that anthropogenic activities are related to the presence of these emerging contaminants (ARBs and ARGs) in the João Leite stream, requiring constant monitoring and research in this area.

Metagenomic Analysis of Bacterial Communities and Antibiotic Resistance Genes in Penaeus monodon Biofloc-Based Aquaculture Environments

Biofloc technology (BFT) is one of the most promising technologies in global aquaculture for the purpose of improving water quality, waste treatment, and disease prevention in intensive aquaculture systems. However, characterization of the microbial species and antibiotic resistance potentially present in biofloc-based aquaculture environments is needed. In this study, we used high-throughput sequencing technology to comprehensively compare the bacterial communities in mariculture ponds of Penaeus monodon (P. monodon), by testing of water, biofloc, and intestine of P. monodon. Operational taxonomic units (OTUs) cluster analysis showed that the nine samples tested divided into 45 phyla and 457 genera. Proteobacteria was the dominant bacteria in water, biofloc and prawn intestine. In biofloc and intestine, the Ruegeria (2.23–6.31%) genus represented the largest proportion of bacteria, with Marivita (14.01–20.94%) the largest group in water. Microbial functional annotation revealed that in all the samples, genes encoding metabolism were predominant. The antibiotic resistance gene annotation showed the highest absolute abundance of patB, adeF, OXA-243, and Brucella_suis_mprF from Proteobacteria. PatB (11.33–15.01%), adeF (15.79–18.16%), OXA-243 (35.65%), and Brucella_suis_mprF (10.03%) showed the highest absolute abundance of antibiotic resistance genes in water, biofloc, and intestines, respectively. These findings may greatly increase our understanding of the characteristics of the microbiota of shrimp biofloc-based aquaculture systems and the complex interactions among shrimp, ambient microflora, and environmental variables. It provides a reference basis for policy on breeding, environmental safety, and maintaining food safety in the production of P. monodon.