Occurrence of antibiotics in the main rivers of Shenzhen, China: Association with antibiotic resistance genes and microbial community

Occurrence, distribution, and correlation of antibiotics in the aquatic ecosystem of Poyang Lake Basin, China

The widespread existence and persistence of antibiotics in the aquatic environment, and their extensive ecological risks, have attracted considerable attention. The objective of this study was to evaluate the occurrence and distribution of 25 antibiotics in environmental and biological samples from Poyang Lake Basin in China. SPE-HPLC-MS/MS was used to quantify the concentrations in different matrices. The total concentrations ranged from 144 to 933 ng/L in the water and 346 to 1154 ng/g in the sediment. In the spatial distribution analysis of this basin, the concentrations in the Ganjiang River were generally higher than those in Poyang Lake. The seasonal distribution in the wet and dry seasons showed comparatively higher concentrations during the dry season than the wet season. Additionally, antibiotics were found in various hydrophytes and animals, and the bioconcentration factor values followed the order: emergent plants > floating plants > submerged plants and benthic organisms > ducks > fish. Moreover, correlations among different matrices showed that antibiotics in viviparid snails were significantly positively correlated with those in ducks, and negatively correlated with those in carps, indicating the transmission relationship through the food chain. The results showed the trophic transfer of antibiotics in the food web and their potential environmental impacts on Poyang Lake Basin need constant attention.

Antibiotic resistance genes (ARGs) and their eco-environmental response in the Bohai Sea sediments

Antibiotic resistance genes (ARGs) are an important class of pollutants in the environment. This study investigated the characteristics and ecological effects of ARGs in the Bohai Sea sediments. The results showed that ARGs are widely distributed, and exhibit significant spatial and subtype variations, with absolute abundance following the decreasing order of Liaodong Bay, Laizhou Bay, Bohai Bay, and Bohai Strait. Tetracycline ARGs dominated, comprising 50 % to 62 % of all ARGs, with tetM having the highest abundance at 1.43 × 107 copies/g. Symbiotic network analysis revealed that the phyla Deinococcota, Dadabacteria were serve as the primary likely host of ARGs. The ARGs have a wide range of potential hosts, and bacteria often carry multiple ARGs, enhancing the mobility and ecological niche adaptation of ARGs. This study will provide an important reference for assessing ARGs pollution in semi-enclosed seas.

Occurrence, Source Apportionment, and Risk Assessment of Antibiotics in Mangrove Sediments from the Lianzhou Bay, China

In recent years, the widespread application of antibiotics has raised global concerns, posing a severe threat to ecological health. In this study, the occurrence, source, and ecological risks of 39 antibiotics belonging to 5 classes in mangrove sediments from Lianzhou Bay, China, were assessed. The total concentrations of the antibiotics (∑39 antibiotics) ranged from 65.45 to 202.24 ng/g dry weight (dw), with an average of 142.73 ± 36.76 ng/g dw. The concentrations of these five classes of antibiotics were as follows: Sulfonamides (SAs) > Tetracyclines (TCs) > Fluoroquinolones (QUs) > Penicillin (PCs) > Macrolides (MLs). The spatial distribution of antibiotics varied as high tidal zone > middle tidal zone > low tidal zone. The total organic carbon (TOC), pH, nitrate (NO3--N), and nitrite (NO2--N) of the sediment significantly influenced the distribution of antibiotics (p < 0.05). A source analysis identified untreated sewage from aquaculture as the primary source of antibiotics in the local mangrove. A risk assessment revealed that ciprofloxacin, norfloxacin, ofloxacin of QUs, and tetracycline of TCs exhibited medium risks to algae in certain sampling sites, while other antibiotics exhibited low or no risks to all organisms. Nevertheless, the total risk of all the detected antibiotics to algae was medium in 95% of the sites. The overall ecological risk level of antibiotics in the middle tidal zone was slightly lower than in the high tidal zone and the lowest in the low tidal zone. In summary, the experimental results provided insights into the fate and transport behaviors of antibiotics in mangrove sediments from Lianzhou Bay.

Meta-analysis of wastewater microbiome for antibiotic resistance profiling

The microbial composition and stress molecules are main drivers influencing the development and spread of antibiotic resistance bacteria (ARBs) and genes (ARGs) in the environment. A reliable and rapid method for identifying associations between microbiome composition and resistome remains challenging. In the present study, secondary metagenome data of sewage and hospital wastewaters were assessed for differential taxonomic and ARG profiling. Subsequently, Random Forest (RF)-based ML models were used to predict ARG profiles based on taxonomic composition and model validation on hospital wastewaters. Total ARG abundance was significantly higher in hospital wastewaters (15 ppm) than sewage (5 ppm), while the resistance towards methicillin, carbapenem, and fluoroquinolone were predominant. Although, Pseudomonas constituted major fraction, Streptomyces, Enterobacter, and Klebsiella were characteristic of hospital wastewaters. Prediction modeling showed that the relative abundance of pathogenic genera Escherichia, Vibrio, and Pseudomonas contributed most towards variations in total ARG count. Moreover, the model was able to identify host-specific patterns for contributing taxa and related ARGs with >90% accuracy in predicting the ARG subtype abundance. More than >80% accuracy was obtained for hospital wastewaters, demonstrating that the model can be validly extrapolated to different types of wastewater systems. Findings from the study showed that the ML approach could identify ARG profile based on bacterial composition including 16S rDNA amplicon data, and can serve as a viable alternative to metagenomic binning for identification of potential hosts of ARGs. Overall, this study demonstrates the promising application of ML techniques for predicting the spread of ARGs and provides guidance for early warning of ARBs emergence.

Removal of Amoxicillin From Wastewater Onto Activated Carbon: Optimization of Analytical Parameters by Response Surface Methodology

Antibiotics are widely used in veterinary and human medicine, but these compounds, when released into the aquatic environment, present potential risks to living organisms. In the present study, the activated carbon (AC) used for their removals is characterized by FT-IR spectroscopy, BET analysis and Scanning Electron Microscopy (SEM) to determine the physicochemical characteristics. Response surface methodology (RSM) and Box-Behnken statistical design (BBD) were used to optimize important parameters including pH (2-12), temperature (20-45°C), and AC dose (0.05-0.20 g). The experimental data were analyzed by analysis of variance (ANOVA) and fitted to second-order polynomial using multiple regression analysis. The optimal conditions for maximum elimination of Amoxicillin (Amox) are (Dose: 0.124 g, pH 5.03 and 45°C) by applying the desirability function (df). A confirmation experiment was carried out to evaluate the accuracy of the optimization model and maximum removal efficiency (R = 89.999%) was obtained under the optimized conditions. Several error analysis equations were used to measure goodness of fit. Pareto analysis suggests the importance of the relative order of factors: pH > Temperature > AC dose in optimized situations. The equilibrium adsorption data of Amox on Activated Carbone were analyzed by Freundlich, Elovich, Temkin and Langmuir models. The latter gave the best correlation with qmax capacities of 142.85 mg/g (R2 = 0.999) at 25°C is removed from solution. The adsorption process is dominated by chemisorption and the kinetic model obeys a pseudo-second order model (R2 = 0.999).

Interaction patterns and keystone taxa of bacterial and eukaryotic communities during sulfamethoxazole mineralization in lake sediment

Sulfamethoxazole (SMX) is a common antibiotic pollutant in aquatic environments, which is highly persistent under various conditions and significantly contributes to the spread of antibiotic resistance. Biodegradation is the major pathway to eliminate antibiotics in the natural environment. The roles of bacteria and eukaryotes in the biodegradation of antibiotics have received considerable attention; however, their successions and co-occurrence patterns during the biodegradation of antibiotics remain unexplored. In this study, 13C-labled SMX was amended to sediment samples from Zhushan Bay (ZS), West Shore (WS), and Gonghu Bay (GH) in Taihu Lake to explore the interplay of bacterial and eukaryotic communities during a 30-day incubation period. The cumulative SMX mineralization on day 30 ranged from 5.2 % to 19.3 %, which was the highest in WS and the lowest in GH. The bacterial community showed larger within-group interactions than between-group interactions, and the positive interactions decreased during incubation. However, the eukaryotic community displayed larger between-group interactions than within-group interactions, and the positive interactions increased during incubation. The proportion of negative interactions between bacteria and eukaryotes increased during incubation. Fifty genera (including 46 bacterial and 4 eukaryotic genera) were identified as the keystone taxa due to their dominance in the co-occurrence network and tolerance to SMX. The cumulative relative abundance of these keystone taxa significantly increased during incubation and was consistent with the SMX mineralization rate. These taxa closely cooperated and played vital roles in co-occurrence networks and microbial community interactions, signifying their crucial role in SMX mineralization. These findings broadened our understanding of the complex interactions of microorganisms under SMX exposure and their potential functions during SMX mineralization, providing valuable insights for in situ bioremediation.

Airborne ARGs/MGEs from two sewage types during the COVID-21: Population, microbe interactions, cytotoxicity, formation mechanism, and dispersion

During the COVID-2021 epidemic, a large number of antibiotics were used for clinical treatment in hospitals or daily prevention. Sewage from hospital sewage treatment centers (HSTC) and wastewater treatment plants (WWTP) produced a lot of antibiotic-resistance genes/mobile genetic elements (ARGs/MGEs). In this study, the sewage and bioaerosol in the biochemical tank (BT) of an HSTC and a WWTP were sampled throughout the year. The results showed that the average absolute abundance of sewage in BT of WWTP (BTW-W) was higher than sewage in BT of HSTC (BTW-H). Sewage was an important source of microorganisms and ARGs/MGEs in the air of BT. Microorganisms and MGEs were the factors affecting the differences in ARGs/MGEs. Cytotoxicity experiment proved that the cytotoxicity changed from Grade III to Grade IV with the increase in drug-resistant Escherichia coli concentration. According to the formation mechanism formula, the average generation rate of ARGs/MGEs in BT of HSTC was lower than that in WWTP. The diffusion range of ARGs/MGEs of HSTC was larger than that of WWTP. According to the above results, this study found that when people were far away from BT, the health risk of HSTC caused by the diffusion of bioaerosol was higher than WWTP; When people were close to BT, the health risk of WWTP was higher than HSTC due to the aeration of BT. This study provided a basis for public protection of ARGs. In the future, the elimination of airborne ARGs and crowd protection can be further studied in detail.

Occurrence and distribution of antibiotics and antibiotic resistance genes from the land to ocean in Daliao River-Liaodong Bay, China

In this study, the pollution status of antibiotics and ARGs in sediments from the land-sea intersection of Liaodong Bay was analyzed. The results showed that the level of antibiotic pollution ranged from ND to 433.27 ng/kg, with quinolones and tetracycline as the dominant antibiotics. The relative abundance of ARGs ranged from 3.62 × 10-3 to 1.32 × 10-1 copies/16SrRNA copies, with aminoglycoside and MLSB resistance genes being dominant. Regarding spatial distribution, the land and estuary areas showed higher antibiotic pollution levels than the offshore areas. Similarly, the land and estuary areas exhibited higher antibiotic diversity than the offshore areas. The ARGs were widely distributed on land, and their abundance gradually decreased to the downstream estuary area. Land and coastal areas exhibited higher ARG diversity than estuary areas. Analysis of environmental factors revealed a significant correlation between ARGs and non-corresponding antibiotics, and some ARGs were affected by heavy metals Cu and Pb.

Relationships between high-concentration toxic metals in sediment and evolution of microbial community structure and carbon-nitrogen metabolism functions under long-term stress perspective

Microorganisms are highly sensitive to toxic metal pollution and play an important role in the material cycling and energy flow of the water ecosystem. Herein, 13 sediment samples from Junchong Reservoir (Guangxi Province, China) were collected in December 2021. The spatial distribution of pollution levels for toxic metals and the effects of toxic metals on the composition, functional characteristics, and metabolism of microorganisms were investigated. The results demonstrated that the area is a proximate area to industrial zones with severity of toxic metal pollution. Their mean concentrations of As, Cu, Zn, and Pb were up to 128.79 mg/kg, 57.62 mg/kg, 594.77 mg/kg, and 97.12 mg/kg respectively. There was a strong correlation between As, Cu, Zn, and Pb, with the highest correlation coefficient reaching 0.94. As the level of toxic metal pollution increases, the diversity and abundance of microorganisms gradually decrease. Compared to those with lower pollution levels, the Shannon index in regions with higher pollution levels decreases by up to 0.373, and the Chao index decreases by up to 143.507. However, the relative abundance of Bacteroidota, Patescibacteria, and Chloroflexi increased by 23%, 20%, and 5%, respectively, indicating their higher adaptability to toxic metals. Furthermore, microbial carbon and nitrogen metabolism were also affected by the presence of toxic metals. FAPROTAX analysis demonstrated an abundant reduction of ecologically functional groups associated with carbon and nitrogen transformations under high toxic metal pollution levels. KEGG pathway analysis indicated that carbon fixation and nitrogen metabolism pathways were inhibited with increasing toxic metal concentrations. These findings would contribute to a better understanding of the effects of toxic metal pollution on sediment microbial communities and function, shedding light on the ecological consequences of toxic metal contamination.

Oxygen mediated mobilization and co-occurrence of antibiotic resistance in lab-scale bioreactor using metagenomic binning

Sub-lethal levels of antibiotic stimulate bacteria to generate reactive oxygen species (ROS) that promotes emergence and spread of antibiotic resistance mediated by mobile genetic elements (MGEs). Nevertheless, the influence of dissolved oxygen (DO) levels on mobility of antibiotic resistance genes (ARGs) in response to ROS-induced stress remains elusive. Thus, the study employs metagenomic assembly and binning approaches to decipher mobility potential and co-occurrence frequency of ARGs and MGEs under hyperoxic (5.5-7 mgL- 1), normoxic (2.5-4 mgL- 1), and hypoxic (0.5-1 mgL- 1) conditions in lab-scale bioreactor for 6 months. Among 163 high-quality metagenome-assembled genomes (MAGs) recovered from 13 metagenomes, 42 MAGs harboured multiple ARGs and were assigned to priority pathogen group. Total ARG count increased by 4.3 and 2.5% in hyperoxic and normoxic, but decreased by 0.53% in hypoxic conditions after 150 days. On contrary, MGE count increased by 7.3-1.3% in all the DO levels, with only two ARGs showed positive correlation with MGEs in hypoxic compared to 20 ARGs under hyperoxic conditions. Opportunistic pathogens (Escherichia, Klebsiella, Clostridium, and Proteus) were detected as potential hosts of ARGs wherein co-localisation of critical ARG gene cassette (sul1, dfr1,adeF, and qacC) were identified in class 1 integron/Tn1 family transposons. Thus, enhanced co-occurrence frequency of ARGs with MGEs in pathogens suggested promotion of ARGs mobility under oxidative stress. The study offers valuable insights into ARG dissemination and hosts dynamics that is essential for controlling oxygen-related stress for mitigating MGEs and ARGs in the environment.

Intraparticle sorption and desorption of antibiotics

Intraparticle domains are the critical locations for storing contaminants and retarding contaminant transport in subsurface environments. While the kinetics and extent of antibiotics sorption and desorption in subsurface materials have been extensively studied, their behaviors in intraparticle domains have not been well understood. This study investigated the sorption and desorption of antibiotics (ATs) in the intraparticle domains using quartz grains and clay, and antibiotic tetracycline (TC) and levofloxacin (LEV) as examples that are commonly present in groundwater systems. Batch experiments coupled with the analyses using various microscopic and spectroscopic techniques were performed to investigate the sorption and desorption kinetics, and to provide insights into the intraparticle sorption and desorption of TC and LEV. Results indicated that both TC and LEV with different physiochemical properties can migrate into intraparticle domains that were consistent with sorptive diffusion. The rate and extent of the sorption are a function of intraparticle surface area and properties, pore volume and connectivity, and ionic properties of the ATs. The sorptive diffusion led to the slow desorption of both TC and LEV after their sorption, apparently showing an irreversible desorption behavior (with desorption percentage about 1.86-20.51%). These results implied that intraparticle domains can be important locations for storing ATs, retarding ATs transport, and may serve as a long-term secondary source for groundwater contamination.

Investigating the antibiotic resistance genes and their potential risks in the megacity water environment: A case study of Shenzhen Bay Basin, China

Antibiotic resistance genes (ARGs) constitute emerging pollutants and pose serious risks to public health. Anthropogenic activities are recognized as the main driver of ARG dissemination in coastal regions. However, the distribution and dissemination of ARGs in Shenzhen Bay Basin, a typical megacity water environment, have been poorly investigated. Here, we comprehensively profiled ARGs in Shenzhen Bay Basin using metagenomic approaches, and estimated their associated health risks. ARG profiles varied greatly among different sampling locations with total abundance ranging from 2.79 × 10-2 (Shenzhen Bay sediment) to 1.04 (hospital sewage) copies per 16S rRNA gene copy, and 45.4% of them were located on plasmid-like sequences. Sewage treatment plants effluent and the corresponding tributary rivers were identified as the main sources of ARG contamination in Shenzhen Bay. Mobilizable plasmids and complete integrons carrying various ARGs probably participated in the dissemination of ARGs in Shenzhen Bay Basin. Additionally, 19 subtypes were assigned as high-risk ARGs (Rank I), and numerous ARGs were identified in potential human-associated pathogens, such as Burkholderiaceae, Rhodocyclaceae, Vibrionaceae, Pseudomonadaceae, and Aeromonadaceae. Overall, Shenzhen Bay represented a higher level of ARG risk than the ocean environment based on quantitative risk assessment. This study deepened our understanding of the ARGs and the associated risks in the megacity water environment.

Occurrence of selected antibiotics in urban rivers in northwest Pakistan and assessment of ecotoxicological and antimicrobial resistance risks

Antibiotics in aquatic systems of developing countries are a growing concern, particularly with the potential ecological risks and emergence of antimicrobial resistance. In Pakistan, antibiotics are widely consumed and released untreated into rivers, however, there is little information on their occurrence and potential risks. In this study, the concentrations and risk assessment of three commonly consumed antibiotics, ciprofloxacin (CIP), amoxicillin (AMX), and cefixime (CFM) belonging to different classes of fluoroquinolone, penicillin, and cephalosporin respectively were investigated in the Kabul River and its two tributaries, Bara River and Shah Alam River in the northwest region of the country. Composite samples were collected in different sampling campaigns and analyzed using the LC-ESI-MS/MS technique. All three antibiotics were found in higher concentrations ranging from 410 to 1810 ng/L, 180-850 ng/L, and 120-600 ng/L for CIP, AMX, and CFM respectively. The Friedman and Wilcoxon signed-ranked tests revealed insignificant differences in average concentrations of each antibiotic in the three rivers and the Pearson Correlation showed a significant positive correlation of CIP with both AMX and CFM indicating their similar pollution sources. Ecotoxicological risk assessment showed a higher risk to algae and bacteria (P. putida) in the rivers with CIP posing a greater risk. The potential risk of antimicrobial resistance development (ARD) was higher in all the three rivers, particularly in Kabul River where maximum risk quotients (RQARD) of 28.3, 9.4 and 3.4 were noted for CIP, CFM and AMX respectively. The human health (HH) risk was insignificant, though the RQHH was higher for the lower age groups (0-3 months). In addition, the combined flux of the antibiotics in the Kabul River was estimated as 59 tons/year with CIP having a significant flux relative to the other antibiotics.

Addressing the challenges of combined sewer overflows

Europe's ageing wastewater system often combines domestic sewage with surface runoff and industrial wastewaters. To reduce the associated risk of overloading wastewater treatment works during storms, and to prevent wastewater backing-up into properties, Combined Sewer Overflows (CSOs) are designed into wastewater networks to release excess discharge into rivers or coastal waters without treatment. In view of growing regulatory scrutiny and increasing public concern about their excessive discharge frequencies and potential impacts on environments and people, there is a need to better understand these impacts to allow prioritisation of cost-effective solutions.We review: i) the chemical, physical and biological composition of CSOs discharges; ii) spatio-temporal variations in the quantity, quality and load of overflows spilling into receiving waters; iii) the potential impacts on people, ecosystems and economies. Despite investigations illustrating the discharge frequency of CSOs, data on spill composition and loading of pollutants are too few to reach representative conclusions, particularly for emerging contaminants. Studies appraising impacts are also scarce, especially in contexts where there are multiple stressors affecting receiving waters. Given the costs of addressing CSOs problems, but also the likely long-term gains (e.g. economic stimulation as well as improvements to biodiversity, ecosystem services, public health and wellbeing), we highlight here the need to bolster these evidence gaps. We also advocate no-regrets options to alleviate CSO problems taking into consideration economic costs, carbon neutrality, ecosystem benefit and community well-being. Besides pragmatic, risk-based investment by utilities and local authorities to modernise wastewater systems, these include i) more systemic thinking, linking policy makers, consumers, utilities and regulators, to shift from local CSO issues to integrated catchment solutions with the aim of reducing contributions to wastewater from surface drainage and water consumption; ii) broader societal responsibilities for CSOs, for example through improved regulation, behavioural changes in water consumption and disposal of waste into wastewater networks, and iii) greater cost-sharing of wastewater use.

Identification of functional microflora underlying the biodegradation of sulfadiazine-contaminated substrates by Hermetia illucens

The increasing discharge of antibiotic residues into the natural environment, stemming from both human activities and animal farming, has detrimental effects on natural ecosystems and serves as a significant driving force for the spread of antibiotic resistance. Biodegradation is an important method for the elimination of antibiotics from contaminated substrates, but the identifying in situ microbial populations involved in antibiotic degradation is challenging. Here, DNA stable isotope probing (DNA-SIP) was employed to identify active sulfadiazine (SDZ) degrading microbes in the gut of black soldier fly larvae (BSFLs). At an initial SDZ concentration of 100 mg kg-1, the highest degradation efficiency reached 73.99% after 6 days at 28 °C. DNA-SIP revealed the incorporation of 13C6 from labeled SDZ in 9 genera, namely, Clostridum sensu stricto 1, Nesterenkonia, Bacillus, Halomonas, Dysgonomonas, Caldalkalibacillus, Enterococcus, g_unclassified_f_Xanthomonadaceae and g_unclassified_f_Micrococcaceae. Co-occurrence network analysis revealed that a significant positive correlation existed among SDZ degrading microbes in the gut microbiota, e.g., between Clostridium sensu stricto 1 and Nesterenkonia. Significant increases in carbohydrate metabolism, membrane transport and translation were crucial in the biodegradation of SDZ in the BSFL gut. These results elucidate the structure of SDZ-degrading microbial communities in the BSFL gut and in situ degradation mechanisms.

Maternal or Paternal Antibiotics? Intergenerational Transmission and Reproductive Toxicity in Zebrafish

Despite the known direct toxicity of various antibiotics to aquatic organisms, the potential chronic impact through intergenerational transmission on reproduction remains elusive. Here, we exposed zebrafish to a mixture of 15 commonly consumed antibiotics at environmentally relevant concentrations (1 and 100 μg L-1) with a cross-mating design. A high accumulation of antibiotics was detected in the ovary (up to 904.58 ng g-1) and testis (up to 1704.49 ng g-1) of F0 fish. The transmission of antibiotics from the F0 generation to the subsequent generation (F1 offspring) was confirmed with a transmission rate (ki) ranging from 0.11 to 2.32. The maternal transfer of antibiotics was significantly higher, relative to paternal transfer, due to a greater role of transmission through ovarian enrichment and oviposition compared to testis enrichment. There were similar impairments in reproductive and developmental indexes on F1 eggs found following both female and male parental exposure. Almost all antibiotics were eliminated in F2 eggs in comparison to F1 eggs. However, there were still reproductive and developmental toxic responses observed in F2 fish, suggesting that antibiotic concentration levels were not the only criterion for evaluating the toxic effects for each generation. These findings unveil the intergenerational transmission mechanism of antibiotics in fish models and underscore their potential and lasting impact in aquatic environments.

Parabens as environmental contaminants of aquatic systems affecting water quality and microbial dynamics

Among different pollutants of emerging concern, parabens have gained rising interest due to their widespread detection in water sources worldwide. This occurs because parabens are used in personal care products, pharmaceuticals, and food, in which residues are generated and released into aquatic environments. The regulation of the use of parabens varies across different geographic regions, resulting in diverse concentrations observed globally. Concentrations of parabens exceeding 100 μg/L have been found in wastewater treatment plants and surface waters while drinking water (DW) sources typically exhibit concentrations below 6 μg/L. Despite their low levels, the presence of parabens in DW is a potential exposure route for humans, raising concerns for both human health and environmental microbiota. Although a few studies have reported alterations in the functions and characteristics of microbial communities following exposure to emerging contaminants, the impact of the exposure to parabens by microbial communities, particularly biofilm colonizers, remains largely understudied. This review gathers the most recent information on the occurrence of parabens in water sources, as well as their effects on human health and aquatic organisms. The interactions of parabens with microbial communities are reviewed for the first time, filling the knowledge gaps on the effects of paraben exposure on microbial ecosystems and their impact on disinfection tolerance and antimicrobial resistance, with potential implications for public health.

Occurrence of sulfonamides and tetracyclines in the coastal areas of the Yangtze River (China) Estuary

Antibiotics have attracted global attention due to the ecological risks to environment. In this paper, solid-phase extraction and ultra-performance liquid chromatography triple quadrupole mass spectrometry (LC-MS/MS) were utilized to analyze the fugitive characteristics of 10 antibiotics of sulfonamides (sulfadiazine, sulfamethazine, sulfadimidine, sulfathiazole, sulfapyridine, sulfamethoxazole) and tetracyclines (tetracycline, oxytetracycline, chlortetracycline and doxycycline) in the coastal waters and surfece sediments of the Yangtze River Estuary and the ecological risks of antibiotics in water were estimated using ecological risk assessment method. The results have showed that 7 of the 10 antibiotics were detected in the water, with total concentrations ranging from 0.652 to 434.47 ng/L. 8 antibiotics were detected in the sediment, with total concentrations ranging from 0.091 to 499.23 ng/g. The main antibiotic species detected in the sediment and water varied seasonally. Higher concentrations in spatially distributed areas where rivers meet and where human activities have a more significant impact. The ecological risks were found to be higher in spring and autumn than those in winter and summer. Spatial variation in individual microbial communities was not evident in the sediments. The relationship between antibiotics and microorganisms in the environment was predominantly positive. Physical and chemical factors were significantly correlated for both antibiotics and microbial communities. This study can provide research ideas for other types of antibiotics and provide a basis for the prevention of antimicrobial resistance (AMR).

Effects of water environmental factors and antibiotics on bacterial community in urban landscape lakes

The presence of antibiotics can affect the natural microbial community and exert selective pressure on the environment's microorganisms. This study focused on three types of urban landscape lakes in Xi'an that were closely related to human activities. By combining basic water quality indicators, antibiotic occurrence status, bacterial communities and their potential metabolic functions, Spearman correlation coefficient and redundancy analysis were used to explore the relationship between them, and further explore the impact mechanism of environmental factors and antibiotics on bacterial community structure. The results showed that ofloxacin, erythromycin, and roxithromycin were the main types of antibiotics in the three landscape lakes, with low ecological risks, and there was a clear clustering of antibiotic occurrence. Proteobacteria was the most abundant bacterial phylum, and each lake had its own unique dominant bacteria, which indicates that they are influenced by varying water sources, pollution, and other nearby environments. Statistical analysis showed that pH and nitrogen nutrients were the most critical environmental factors affecting bacterial communities (P<0.01), while tetracyclines and lincomycins were the antibiotics that had a significant impact on bacterial communities (P<0.05). Antibiotics mainly promote defense- and signal transduction-related functions, and inhibit the metabolic activity of bacterial communities. However, the impact of antibiotics on bacterial diversity, community structure, and potential metabolic function in the three urban lakes was less than that of environmental factors. These results help to clarify the mechanism and degree of impact of different interference factors (environmental factors, conventional pollutants, and antibiotics) on bacterial communities in the water environment and are important for the management of urban landscape lake water environments.

Distribution and relationship of antibiotics, heavy metals and resistance genes in the upstream of Hanjiang River Basin in Shiyan, China

The upstream basin of Hanjiang River is an important water source for the middle route of China's South-to-North Water Diversion Project. The quality of water and soil in the Hanjiang River have enormous biological and environmental impacts, and resistant genetic contamination has emerged, but only few studies are concerned the correlation between heavy metals and metal resistance genes (MRGs). In this study, 8 antibiotics and 19 heavy metals were analyzed, the results showed that the highest antibiotic content was tetracycline, with mean concentrations of 43.201 µg/kg and 0.022 µg/L. Mn was the highest heavy metal in soil with a content of 1408.284 µg/kg, and in water was Zn with a content of 10.611 µg/L. We found that the most abundant antibiotic resistance genes (ARGs) and metal resistance genes (MRGs) in the study area were bacA and arsT genes, coding for resistance mechanisms to bacitracin and arsenic, respectively. The data showed that heavy metals had a greater impact on antibiotic resistance genes than antibiotics, and the correlation between resistance genes was significantly positive. This work expands our understanding of the correlations of antibiotics, heavy metals, and resistance genes in the Hanjiang River, indicating that more attention should be paid to the effects of resistance genes and the quality of water.

Pheromone effect of estradiol regulates the conjugative transfer of pCF10 carrying antibiotic resistance genes

Horizontal gene transfer (HGT) mediated by conjugative plasmids greatly contributes to bacteria evolution and the transmission of antibiotic resistance genes (ARGs). In addition to the selective pressure imposed by extensive antibiotic use, environmental chemical pollutants facilitate the dissemination of antibiotic resistance, consequently posing a serious threat to the ecological environment. Presently, the majority of studies focus on the effects of environmental compounds on R plasmid-mediated conjugation transfer, and pheromone-inducible conjugation has largely been neglected. In this study, we explored the pheromone effect and potential molecular mechanisms of estradiol in promoting the conjugative transfer of pCF10 plasmid in Enterococcus faecalis. Environmentally relevant concentrations of estradiol significantly increased the conjugative transfer of pCF10 with a maximum frequency of 3.2 × 10^-2, up to 3.5-fold change compared to that of control. Exposure to estradiol induced the activation of pheromone signaling cascade by increasing the expression of ccfA. Furthermore, estradiol might directly bind to the pheromone receptor PrgZ and promote pCF10 induction and finally enhance the conjugative transfer of pCF10. These findings cast valuable insights on the roles of estradiol and its homolog in increasing antibiotic resistance and the potential ecological risk.

Spatiotemporal distributions of sulfonamide and tetracycline resistance genes and microbial communities in the coastal areas of the Yangtze River Estuary

In this paper, water and sediments were sampled at eight monitoring stations in the coastal areas of the Yangtze River Estuary in summer and autumn 2021. Two sulfonamide resistance genes (sul1 and sul2), six tetracycline resistance genes (tetM, tetC, tetX, tetA, tetO, and tetQ), one integrase gene (intI1), 16 S rRNA genes, and microbial communities were examined and analyzed. Most resistance genes showed relatively higher abundance in summer and lower abundance in autumn. One-way analysis of variance (ANOVA) showed significant seasonal variation of some ARGs (7 ARGs in water and 6 ARGs in sediment). River runoff and WWTPs are proven to be the major sources of resistance genes along the Yangtze River Estuary. Significant and positive correlations between intI1 and other ARGs were found in water samples (P < 0.05), implying that intI1 may influence the spread and propagation of resistance genes in aquatic environments. Proteobacteria was the dominant phylum along the Yangtze River Estuary, with an average proportion of 41.7%. Redundancy analysis indicated that the ARGs were greatly affected by temperature, dissolved oxygen, and pH in estuarine environments. Network analysis showed that Proteobacteria and Cyanobacteria were the potential host phyla for ARGs in the coastal areas of the Yangtze River Estuary.

System comprehensive risk assessment of urban rainstorm-induced flood-water pollution disasters

The urban rainstorm-induced flood-water pollution disaster is a kind of systematic risk, which may induce secondary disasters that can lead to more serious damage, so this paper first adopts the fuzzy comprehensive evaluation method to determine the flood risk by combining with the submergence depth derived from the risk field and other factors data, and then the grid environmental risk evaluation method, which is improved by increasing the induced possibility based on Bayesian theory, is used to evaluate the flood-induced water pollution risk, and the system comprehensive risk of rainstorm-induced flood-water pollution disasters is finally obtained by constructing risk level matrix, which can well depict the coupling superposition effect. Shenzhen City is selected as the study area, and the results showed that the area with high-risk of both flood and water pollution only accounts for about 0.14% of the total area, mainly distributed in the eastern junction of Longgang district and Pingshan district, where the rainstorms occur frequently and the enterprise risk sources are dense. The system comprehensive risk is mostly very low-low and very high-low, accounting for more than 76% of the total area. It is always necessary to pay attention not only to the areas with high risk level of both disasters, but also to the areas with high risk level of one disaster. The method proposed in this study can not only quantitatively reveal the formation of the induced risk, but also provide reference for early warning.

Insight into pharmaceutical and personal care products removal using constructed wetlands: A comprehensive review

Pharmaceutical and personal care products (PPCPs) were regarded as emerging environmental pollutants due to their ubiquitous appearance and high environmental risks. The wastewater treatment plants (WWTPs) became the hub of PPCPs receiving major sources of PPCPs used by humans. Increasing concern has been focused on promoting cost-effective ways to eliminate PPCPs within WWTPs for blocking their route into the environment through effluent discharging. Among all advanced technologies, constructed wetlands (CWs) with a combination of plants, substrates, and microbes attracted attention due to their cost-effectiveness and easier maintenance during long-term operation. This study offers baseline data for risk control and future treatment by discussing the extent and dispersion of PPCPs in surface waters over the past ten years and identifying the mechanisms of PPCPs removal in CWs based on the up-to-present research, with a special focus on the contribution of sediments, vegetation, and the interactions of microorganisms. The significant role of wetland plants in the removal of PPCPs was detailed discussed in identifying the contribution of direct uptake, adsorption, phytovolatilization, and biodegradation. Meanwhile, the correlation between the physical-chemical characteristics of PPCPs, the configuration operation of wetlands, as well as the environmental conditions with PPCP removal were also further estimated. Finally, the critical issues and knowledge gaps before the real application were addressed followed by promoted future works, which are expected to provide a comprehensive foundation for study on PPCPs elimination utilizing CWs and drive to achieve large-scale applications to treat PPCPs-contaminated surface waters.

Spatial Distribution and Risk Assessment of Antibiotics in 15 Pharmaceutical Plants in the Pearl River Delta

Pharmaceutical plants are an essential source of antibiotics emitted into the aqueous environment. The monitoring of target antibiotics in pharmaceutical plants through various regions is vital to optimize contaminant release. The occurrence, distribution, removal, and ecological risk of 30 kinds of selected antibiotics in 15 pharmaceutical plants in the Pearl River Delta (PRD) were investigated in this study. Lincomycin (LIN) showed the highest concentration (up to 56,258.3 ng/L) in the pharmaceutical plant influents from Zhongshan city. Norfloxacin (NFX) showed a higher detection frequency than other antibiotics. In addition, the spatial distribution of antibiotics in pharmaceutical plants showed significant differences, with higher concentrations of total antibiotics found in pharmaceutical plant influents in Shenzhen City than those of different regions in PRD. The treatment processes adopted by pharmaceutical plants were commonly ineffective in removing antibiotics, with only 26.7% of antibiotics being effectively removed (average removal greater than 70%), while 55.6% of antibiotics had removal rates of below 60%. The anaerobic/anoxic/oxic (AAO)-membrane bioreactor (MBR) combined process exhibited better treatment performance than the single treatment process. Sulfamethoxazole (SMX), ofloxacin (OFL), erythromycin-H₂O (ETM-H₂O), sulfadiazine (SDZ), sulfamethazine (SMZ), norfloxacin (NFX), and ciprofloxacin (CIP) in pharmaceutical plant effluents posed high or moderate ecological risk and deserve particular attention.

Trends in removal of pharmaceuticals in contaminated water using waste coffee and tea-based materials with their derivatives

The introduction of large amounts of pharmaceuticals into the environmental waters is well-documented in literature with their occurrence reported in all different water matrices accessible to humans and animals. At the same time, the increasing consumption of coffee and tea-based beverages results in the generation of solid waste, which is mostly disposed-off in the environment. To minimize environmental pollution, coffee and tea-based materials have been proposed as suitable options to remove pharmaceuticals in environmental waters. Therefore, this article provides a critical review on the preparation and applications of coffee and tea-based materials in removing pharmaceuticals from contaminated water. In this context, most studies in literature focused on the applications of these materials as adsorbents, while only limited work on their role in degradation of pharmaceuticals is discussed. The successful application in adsorption studies is attributed to high surface areas of adsorbents and the ability to easily modify the adsorbent surfaces by incorporating functional groups that provide additional oxygen atoms, which promote easy interactions with pharmaceuticals. Hence, the adsorption mechanisms are mostly described by hydrogen bonding, electrostatic and π-π interactions with sample pH playing a dominant role in the adsorption process. Overall, the present article focused on the developments, trends and future research direction on the preparations and applications of coffee and tea-based materials for efficient removal of pharmaceuticals in water. PRACTITIONER POINTS: Review of tea and coffee wastes application for removal of pharmaceuticals in water Key applications in adsorption and degradation of pharmaceuticals in water Removal mostly explained by hydrogen bonding, electrostatic, and π-π interactions Trends, gaps, and future research to be explored are reviewed and highlighted.

Impact of environmental factors on diversity of fungi in sediments from the Shenzhen River Estuary

In this study, to explore the relationship between environmental factors and fungal diversity in the Shenzhen River ecosystem, multiple methods including chemical analysis, culture isolation, qPCR analysis of fungal ITS region and ITS-based Illumina next-generation-sequencing were integrated. A total of 115 isolates were finally isolated and could be classified into 23 genera. Top three abundant genera isolated were Meyerozyma (18 strains), Aspergillus (17 strains) and Penicillium (14 strains). Based on the Illumina sequencing approach, 829 OTUs were affiliated to seven phyla, 17 known classes, and 162 genera, indicating the Shenzhen estuary sediments are rich in fungal diversity. The major fungal genera were Meyerozyma, Trichoderma and Talaromyces. Environmental factors showed a gradient change in Shenzhen estuary, and fungal abundance was only significantly correlated with NH₄⁺. Shannon index was significantly correlated with pH and IC (P < 0.05). Principal coordinate analysis based on OTU level grouped into three clusters among sampling sites along with the IC and pH gradient. Functional guilds analysis suggests most of the fungi in this studying area were almost all saprotrophs, suggesting a large number of saprophytic fungi may play a significant role in the organic matter decomposition and nutrient cycling process. In summary, this study will deepen our understanding of fungi community in Shenzhen River ecosystem and their distribution and potential function shaped by environmental factors.

Human health risk estimation of antibiotics transferred from wastewater and soil to crops

Antibiotics enter into agricultural land, via manure application or wastewater irrigation. The practices of using untreated wastewater in the agricultural system help in the bioaccumulation of antibiotics in vegetables and other crops. Exposure to the bioaccumulated antibiotics poses serious health risks to ecosystem and human. In this study, the prevalence of two fluoroquinolones (levofloxacin and ciprofloxacin), their bioaccumulation in five crops (Daucus carota L., Pisum sativum L., Raphanus raphanistrum L., Lactuca sativa L., Spinacia oleracea L.), and associated human health risks were investigated. Lettuce showed highest bioaccumulation of levofloxacin (LEV) (12.66 μg kg-1) and carrot showed high bioaccumulation of ciprofloxacin (CIP) (13.01 μg kg-1). In roots, bioconcentration factor (BCFroot) was observed to be relatively high in radish (LEV 0.24-0.43, CIP 0.32-0.49) and observed to be lower in spinach (LEV 0.05-0.13, CIP 0.12-0.19). The translocation factor (TF) for LEV and CIP was generally >1 for all five crops under all treatment. The final transfer and distribution of LEV and CIP in the edible parts of the crops were as follows: leaves > shoots > roots for both antibiotics. Risk quotient of both LEV and CIP in current study is found to be in between 0.018 and 0.557 and shows a medium risk (0.1 to 1) to human health due the discharge of untreated wastewater into the fields. However, our study reports that both antibiotics do accumulate in the edible plant parts; therefore, it poses potential risks to human health.

Assessment of sulfamethoxazole toxicity to marine mussels (Mytilus galloprovincialis): Combine p38-MAPK signaling pathway modulation with histopathological alterations

Sulfamethoxazole (SMX), is a ubiquitous antibiotic in the aquatic environment and received concerns on its health hazards, especially its sub-lethal effects on non-target organisms which were remained largely unknown. In the present study, in order to investigate SMX induced tissue damages and reveal underlying mechanisms, marine mussels, Mytilus galloprovincialis were challenged to SMX series (0.5, 50 and 500 μg/L) for six-days followed by six-day-recovery. Comprehensive histopathological alteration (including qualitative, semi-quantitative and quantitative indices), together with transcriptional and (post-) translational responses of key factors (p38, NFκB and p53) in the p38-MAPK signaling pathway were analyzed in gills and digestive glands. Tissue-specific responses were clearly investigated with gills showing more prompt responses and digestive glands showing higher tolerance to SMX. The histopathology showed that SMX triggered inflammatory damages in both tissues and quantitative analysis revealed more significant responses, suggesting its potential as a valuable health indicator. SMX activated expressions of p38, NFκB and p53 at transcriptional and (post-) translational levels, especially after exposed to low level SMX, evidenced by p38 coupled with NFκB/p53 regulation on immunity defense in mussels. Less induction of targeted molecules under severe SMX exposure indicated such signaling transduction may not be efficient enough and can result in inflammatory damages. Taken together, this study expanded the understanding of aquatic SMX induced health risk in marine mussels and the underlying regulation mechanism through p38 signaling transduction.

Structure and function response of bacterial communities towards antibiotic contamination in hyporheic zone sediments

Bacterial communities are crucial for processing and degrading contaminants in hyporheic zones (HZ). However, the effects of antibiotics on HZ bacterial communities have seldom been addressed. Here, using MiSeq 16S amplicon sequencing technology, the effects of acute exposure to Enrofloxacin, Sulfathiazole, Tetracycline hydrochloride, and Penicillin V potassium on HZ bacterial communities were investigated. Results revealed that HZ sediment communities responded differently to different classes of antibiotics, reflecting the distinct selection stress of antibiotics on HZ bacterial communities. Besides, HZ communities from the locations with more severe antibiotic contamination backgrounds (∼150 μg kg^-1) were more resistant towards antibiotic treatment. Compared with small/non-significant changes in HZ community diversity and composition treated with ng L^-1∼ug L^-1 level antibiotics compared to the control group, treatments with antibiotics over mg L^-1 level significantly reduced the diversity and changed the structures of HZ bacterial communities, and enhanced the resistance of the community to antibiotics by enriching antibiotic resistant bacteria. The exposure to mg L^-1 level antibiotics also changed community functions by restricting the growth of functional bacteria, such as ammonia oxidizing bacteria (AOB) Nitrosomonas, resulting in ammonia accumulation in sediments. The results implied that at field-relevant concentrations, there was no or minor effect of antibiotics on HZ bacterial community structure and functions, and only those areas with high antibiotic concentrations would have effects.

Distribution of sediment microbial communities and their relationship with surrounding environmental factors in a typical rural river, Southwest China

With rapid urbanization and industrialization, rural rivers in China are facing deterioration in water quality and ecosystem health. Microorganisms living in river sediments are involved in biogeochemical processes, mineralization, and degradation of pollutants. Understanding bacterial community distribution in rural rivers could help evaluate the response of river ecosystems to environmental pollution and understand the river self-purification mechanism. In this study, the relationship between characteristics of sediment microbial communities and the surrounding environmental factors in a typical rural river was analyzed using 16S rRNA gene sequencing technology. The results showed that the dominant bacterial groups in the river sediment were Proteobacteria, Actinobacteria, Chloroflexi, Acidobacteria, Bacteroidetes, and Firmicutes, accounting for 83.61% of the total microbial load. Different areas have different sources of pollution which give rise to specific dominant bacteria. The upstream part of the river flows through an agricultural cultivation area where the dominant bacteria were norank_f_Gemmatimonadaceae, Haliangium, and Pseudolabrys, possessing obvious nitrogen- and phosphorus-metabolizing activities. The midstream section flows through an urban area where the dominant bacteria were Marmoricola, Nocardioides, Gaiella, Sphingomonas, norank_f_67-14, Subgroup_10, Agromyces, and Lysobacter, with strong metabolizing activity for toxic pollutants. The dominant bacteria in the downstream part were Clostridium_sensu_stricto_1, norank_f__Bacteroidetes_vadinHA17, Candidatus_Competibacter, and Methylocystis. Redundancy analysis and correlation heatmap analysis showed that environmental factors: ammonia nitrogen (NH₄⁺-N) and total nitrogen (TN) in the sediment, and pH, temperature, TN, electrical conductivity (EC), and total dissolved solids (TDS) in the water, significantly affected the bacterial community in the sediment. The PICRUSt2 functional prediction analysis identified that the main function of bacteria in the sediment was metabolism (77.3%), specifically carbohydrate, amino acid, and energy metabolism. These activities are important for degrading organic matter and removing pollutants from the sediments. The study revealed the influence of organic pollutants derived from human activities on the bacterial community composition in the river sediments. It gave a new insight into the relationship between environmental factors and bacterial community distribution in rural watershed ecosystems, providing a theoretical basis for self-purification and bioremediation of rural rivers.

An Overview of the Impact of Pharmaceuticals on Aquatic Microbial Communities

Pharmaceuticals are present as pollutants in several ecosystems worldwide. Despite the reduced concentrations at which they are detected, their negative impact on natural biota constitutes a global concern. The consequences of pharmaceuticals' presence in water sources and food have been evaluated with a higher detail for human health. However, although most of the pharmaceuticals detected in the environment had not been designed to act against microorganisms, it is of utmost importance to understand their impact on the environmental native microbiota. Microbial communities can suffer serious consequences from the presence of pharmaceuticals as pollutants in the environment, which may directly impact public health and ecosystem equilibrium. Among this class of pollutants, the ones that have been studied in more detail are antibiotics. This work aims to provide an overview of the impacts of different pharmaceuticals on environmental biofilms, more specifically in biofilms from aquatic ecosystems and engineered water systems. The alterations caused in the biofilm function and characteristics, as well as bacteria antimicrobial tolerance and consequently the associated risks for public health, are also reviewed. Despite the information already available on this topic, the need for additional data urges the assessment of emerging pollutants on microbial communities and the potential public health impacts.

Parental transfer of an antibiotic mixture induces cardiotoxicity in early life-stage zebrafish: A cross-generational study

Antibiotic residues in the aquatic environment have been shown to induce significant adverse effects on the early-life stage development of aquatic organisms, though the underlying molecular mechanisms of these effects have not been well characterized. In this study, we performed global mRNA-miRNA sequencing, canonical pathway analyses, morphological, physiological, immunohistochemical, and behavioral analyses to comprehensively assess the cross-generational cardiotoxicity and mechanisms of antibiotic mixtures in zebrafish. Following parental treatment to 1 and 100 μg/L antibiotic mixtures (15 of the most commonly detected antibiotics) for 150 days, all 15 assessed antibiotics were detected in the F1 eggs, indicating the cross-generational transfer of antibiotics. Global mRNA-miRNA sequencing functional analysis predicted cardiotoxicity in the F1 generation by using the F1 whole fish. Consistent with canonical pathway analyses, significant cardiotoxicity was observed in F1 larvae, as well as the apoptosis of cardiac cells. Furthermore, let-7a-5p regulated the cardiac hypertrophy signaling pathway, suggesting mechanisms of miRNA of let-7 family mediating cross-generational cardiotoxicity of antibiotics in zebrafish. This study lays some groundwork for developing interventions to prevent parental exposure to environmental pollutants such as antibiotics from adversely affecting offspring development.

Antibiotic resistance genes in Chishui River, a tributary of the Yangtze River, China: Occurrence, seasonal variation and its relationships with antibiotics, heavy metals and microbial communities

The large-scale use and release of antibiotics may create selective pressure on antibiotic resistance genes (ARGs), causing potential harm to human health. River ecosystems have long been considered repositories of antibiotics and ARGs. Therefore, the distribution characteristics and seasonal variation in antibiotics and ARGs in the surface water of the main stream and tributaries of the Chishui River were studied. The concentrations of antibiotics in the dry season and rainy season were 54.18-425.74 ng/L and 66.57-256.40 ng/L, respectively, gradually decreasing along the river direction. The results of antibiotics in the dry season and rainy season showed that livestock and poultry breeding were the main sources in the surface water of the Chishui River basin. Risk assessments indicated high risk levels of OFL in both seasons. In addition, analysis of ARGs and microbial community diversity showed that sul1 and sul3 were the main ARGs in the two seasons. The highest abundance of ARGs was 7.70 × 10⁷ copies/L, and intl1 was significantly positively correlated with all resistance genes (p< 0.01), indicating that it can significantly promote the transmission of ARGs. Proteobacteria were the dominant microorganisms in surface water, with a higher average abundance in the dry season (60.64 %) than in the rainy season (39.53 %). Finally, correlation analyses were performed between ARGs and antibiotics, microbial communities and heavy metals. The results showed that there was a significant positive correlation between ARGs and most microorganisms and heavy metals (p< 0.01), indicating that occurrence and transmission in the environment are influenced by various environmental factors and cross-selection. In conclusion, the persistent residue and transmission of ARGs and their transfer to pathogens are a great threat to human health and deserve further study and attention.

Antibiotic Resistance Genes in River Biofilms: A Metagenomic Approach toward the Identification of Sources and Candidate Hosts

Treated wastewater is a major pathway by which antibiotic resistance genes (ARG) enter aquatic ecosystems. However, knowledge gaps remain concerning the dissemination of specific ARG and their association with bacterial hosts. Here, we employed shotgun metagenomics to track ARG and taxonomic markers in river biofilms along a gradient of fecal pollution depicted by crAssphage signatures. We found strong evidence for an impact of wastewater effluents on both community composition and resistomes. In the light of such simultaneity, we employed a model comparison technique to identify ARG-host relationships from nonassembled metagenomic DNA. Hereby, a major cause of spurious associations otherwise encountered in correlation-based ARG-host analyses was suppressed. For several families of ARG, namely those conferring resistance to beta-lactams, particular bacterial orders were identified as candidate hosts. The found associations of blaFOX and cphA with Aeromonadales or blaPER with Chromatiales support the outcome of independent evolutionary analyses and thus confirm the potential of the methodology. For other ARG families including blaIMP or tet, clusters of bacterial orders were identified which potentially harbor a major proportion of host species. For yet other ARG, like, for example, ant or erm, no particular host candidates were identifiable, indicating their spread across various taxonomic groups.

Selective pressure governs the composition, antibiotic, and heavy metal resistance profiles of Aeromonas spp. isolated from Ba River in Northwest China

The selective pressure of the living surroundings is a key factor in the development of resistance profiles in pathogenic bacteria such as Aeromonas spp. In this study, Aeromonas species were isolated from the Ba River, and their composition, resistance profiles to antibiotics, and heavy metals (HMs) were investigated. The discovery revealed that selective pressure altered the diversity of Aeromonas spp., with Aeromonas veronii being more adaptable to contaminated waters. Long-term exposure to antibiotics or HMs exerts persistent selective pressure on Aeromonas species, leading to the increase in multiple antibiotic resistance (MAR) index and multidrug-resistant (MDR) strains. Furthermore, HMs could drive the co-selection of antibiotic resistance via co-resistance or cross-resistance. bla_TEM, bla_SHV, bla_CTX-M, sul1, czcA, mexA, and mexF were detected at high frequencies in Aeromonas species. Among these resistance phenotypes conferred genes, bla_TEM may be intrinsic in the genome of Aeromonas spp., while mexA and mexF may have been acquired from surrounding environments owing to selective pressure. Resistance genes evolved as a consequence of selective pressure and have been shown to be positively correlated with their prevalence. Our study suggests that the selective pressure of living surroundings significantly contributes to the composition and resistance profiles of Aeromonas spp. in the riverine ecosystem.

Composite of methyl polysiloxane and avocado biochar as adsorbent for removal of ciprofloxacin from waters

Two carbon composite materials were prepared by mixing avocado biochar and methyl polysiloxane (MK). Firstly, MK was dissolved in ethanol, and then the biochar was added at different times. In sample 1 (R1), the time of adding biochar was immediately after dissolving MK in ethanol, and in sample 2 (R₂), after 48 h of MK dissolved in ethanol. The samples were characterized by nitrogen adsorption/desorption measurements obtaining specific surface areas (S_BET) of 115 m2 g^-1 (R₁) and 580 m2 g^-1 (R₂). The adsorbents were further characterized using scanning electron microscopy, FTIR and Raman spectroscopy, adsorption of vapors of n-heptane and water, thermal analysis, Bohem titration, pHpzc, and C H N elemental analysis. R₁ and R₂ adsorbents were employed as adsorbents to remove the antibiotic ciprofloxacin from the waters. The t_1/2 and t_0.95 based on the interpolation of Avrami fractional-order were 20.52 and 246.4 min (R₁) and 14.00 and 157.6 min (R₂), respectively. Maximum adsorption capacities (Q_max) based on the Liu isotherm were 10.77 (R₁) and 63.80 mg g^-1 (R₂) for ciprofloxacin. The thermodynamic studies showed a spontaneous and exothermic process for both samples, and the value of ΔH° is compatible with physical adsorption.

A national online survey of Filipinos' knowledge, attitude, and awareness of antibiotic use and resistance: A cross-sectional study

BACKGROUND

Antibiotic resistance is one of the 21st century's most challenging clinical and public health issues. However, this health issue remains underreported in the Philippines.

AIM

This study examined Filipinos' knowledge, attitude, and awareness regarding antibiotic use and resistance and the associated predictive variables of antibiotic resistance.

METHODS

A cross-sectional design and Strengthening the Reporting of Observational Studies in Epidemiology guidelines were used in this study. Convenience sampling of 3767 participants completed the Eurobarometer survey on antibiotic resistance from October 2021 to February 2022. χ² and regression analysis were used to analyze the data.

RESULTS

Most participants were familiar with the popular types of available antibiotics. Males and healthcare workers had a higher percentage of correct responses on antibiotic resistance knowledge. Participants had moderate to high knowledge levels of antibiotic resistance. Age, educational attainment, profession, antibiotic use in the previous year, and household members taking antibiotics were significant predictors of the level of knowledge of antibiotic resistance. There was a significant difference in participants' sex, age, and educational attainment in their attitudes toward acquisition, hygienic practices, and the role of health professionals in antibiotic resistance.

CONCLUSION

Government agencies and policymakers should consider the identified predictors when establishing policies on antibiotic resistance. This will ensure that antibiotic use is safe and effective.

Chemical characterization of riverine sediments affected by wastewater treatment plant effluent discharge

This study was aimed at assessing the contribution of wastewater treatment effluents to the contamination profile of the sediments of receiving waterways. Three wastewater treatment plants (WWTP) were addressed, encompassing different population equivalent sizes, urbanization degrees and treatment methods translating differences in expected contamination patterns. Within each WWTP system, the assessment targeted the effluent and sediment samples collected upstream and downstream the effluent discharge point; contaminants belonging to several concerning chemical classes (metals and metalloids; pesticides; pharmaceuticals and personal care products, PPCPs; and polycyclic aromatic hydrocarbons, PAHs) were quantified both in effluent and sediment samples. Clear associations between contaminants present in the effluent and corresponding sediment samples were not always verified. In fact, a noticeable difference between the number or abundance of contaminants detected in effluents and in sediments, suggesting that effluents are not always the most likely source (e.g. PAHs). However, sediment contaminants that were likely sourced by the effluents were also identified (e.g. PPCPs). Sediment analysis offers an important historical view of contamination, especially in flowing recipient ecosystems where any characterization over the water matrix is ephemeral and linking exclusively to the moment of sampling. Hence, sediments should be considered for the establishment of WWTP operational benchmarks regulating the emission of contaminants, which is currently focused mostly on effluent composition thus potentially over/underestimating the longer-term impact of effluent discharge in the recipient waterways.

Oxidative stress, autophagy, and apoptosis induced by doxycycline in loach fin cells in vitro

Cytotoxicity, molecular function disorder, mitophagy, and apoptosis were studied in loach fin cells in vitro after exposure to doxycycline (DOX). The semi-lethal concentration of DOX in loach cells was calculated as 668.96 ± 2.83 mol/L. Loss of cell viability and increases in vacuoles and autolysosomes were evident in cells exposed to DOX at 200 and 400 μmol/L, and apoptotic bodies occurred at 600 μmol/L. In addition, Superoxide Dismutase (SOD), catalase (CAT), Na⁺-K⁺-ATPase, and Ca²⁺-ATPase activities increased significantly in cells exposed to 200 μmol/L DOX, and dose-dependent inhibitory effects on activities were observed in cells exposed to 400 and 600 μmol/L DOX. Quantitative gene expression showed that 400 and 600 μmol/L DOX could induce caspase-3- and caspase-8-mediated apoptosis as well as caspase-activated DNase in loach cells. Transcriptome sequencing in DOX vs. control groups found 16,288 differentially expressed genes, among which protein binding (2633, 31.91%) was the most significant in Gene Ontology terms. Furthermore, 11,930 genes were enriched in 298 Kyoto Encyclopedia of Genes and Genomes (KEGG)pathways. The top three upregulated pathways included "lysosome", "protein processing in endoplasmic reticulum", and "proteasome". FPKM analysis indicated that most genes associated with autophagy and in "protein processing in the endoplasmic reticulum", "TNF signaling pathway", and "NF-kappa B signaling pathway" were upregulated. This suggests that at lower concentrations, DOX induces reactive oxidative species (ROS) in loach fin cells to reduce cell proliferation. ROS in turn stimulate oxidant stress, ion excretion capability and mitophagy to maintain cell homeostasis. Apoptosis was induced in cells subjected to higher concentrations of DOX. The transcriptome data and pathways determined in this study will provide a foundation for the analysis of DOX toxicity in loach cells, which must be examined thoroughly to further understand the cytotoxic mechanism of antibiotics in fish cells.

Cytotoxicity and apoptosis induced by enrofloxacin in loach fin cells in vitro

The cytotoxic effect and cell death were studied in loach fin cells in vitro after enrofloxacin (ENR) exposure. The semi-lethal concentration of ENR for loach cells was calculated as 1296.2 ± 3.11 mol/L (about 512.5 mg/L). Loss of cell viability, increase in vacuoles, disappearance of microvilli, and apoptotic bodies were evident in cells exposed to 400, 800, and 1200 μmol/L ENR. Besides, dose-dependent inhibitory effects on SOD, CAT, Na⁺-K⁺-ATPase, and Ca²⁺-ATPase activities were also observed in loach cells exposed to ENR. Quantitative gene expression results showed that ENR induced caspase-3- and caspase-8-mediated apoptosis as well as caspase-activated DNase in loach cells. The findings also indicated a role of JNK pathway in ENR-induced apoptosis in loach cells. Transcriptome sequencing results showed 10,016 differentially expressed genes in ENR vs. control groups, which were all enriched in "Molecular Function" process in GO term. Furthermore, 6763 genes were enriched in 291 KEEG pathways, with most of them belonging to immune and material metabolic pathways. The large number of transcriptome data and pathways determined in this study provide a database foundation for the toxicity analysis of ENR in loach cells, which must be thoroughly examined to further investigate the cytotoxic mechanism of antibiotics in fish cells.

Road runoff as a significant nonpoint source of parabens and their metabolites in urban rivers

Parabens are widely added to food, cosmetics, and medicines as preservatives and are typical contaminants of pharmaceuticals and personal care products (PPCPs). However, their fate and transport in urban watersheds remain largely unexplored. This study investigated the role of road runoff as a critical nonpoint source of parabens and their metabolites in urban rivers based on 73 multimedia (road runoff and dust in different urban land uses, wastewater, stormwater discharge and river water) samples collected from a highly urbanized drainage area. Seven parabens and five metabolites were detected in the road runoff, with mean concentrations of ∑parabens and ∑metabolites equal to 47.5 ng/L and 4710 ng/L, respectively. The concentrations in road runoff were comparable to those in treated wastewater and river water and showed a land use pattern of residential > industrial > commercial. A first flush effect of the contaminants was observed in a heavy rainfall event with an antecedent dry period. In general, the population-based and area-based emission intensities of ∑parabens and ∑metabolites in road runoff were one order of magnitude higher than those in wastewater effluent during the rainfall events. This study provides quantitative evidence that road runoff can be a major pollution source of parabens and their metabolites in rapidly growing cities during the wet season and calls for the integrated management of nonpoint sources to prevent urban river contamination by typical PPCPs.

In silico toxicity evaluation for transformation products of antimicrobials, from aqueous photolysis degradation

This study investigates degradation processes of three antimicrobials in water (norfloxacin, ciprofloxacin, and sulfamethoxazole) by photolysis, focusing on the prediction of toxicity endpoints via in silico quantitative structure-activity relationship (QSAR) of their transformation products (TPs). Photolysis experiments were conducted in distilled water with individual solutions at 10 mg L^-1 for each compound. Identification of TPs was performed by means of LC-TOF-MS, employing a method based on retention time, exact mass fragmentation pattern, and peak intensity. Ten main compounds were identified for sulfamethoxazole, fifteen for ciprofloxacin, and fifteen for norfloxacin. Out of 40 identified TPs, 6 have not been reported in the literature. Based on new data found in this work, and TPs already reported in the literature, we have proposed degradation pathways for all three antimicrobials, providing reasoning for the identified TPs. QSAR risk assessment was carried out for 74 structures of possible isomers. QSAR predictions showed that all 19 possible structures of sulfamethoxazole TPs are non-mutagenic, whereas 16 are toxicant, 18 carcinogenic, and 14 non-readily biodegradable. For ciprofloxacin, 28 out of the 30 possible structures for the TPs are mutagenic and non-readily biodegradable, and all structures are toxicant and carcinogenic. All 25 possible norfloxacin TPs were predicted mutagenic, toxicant, carcinogenic, and non-readily biodegradable. Results obtained from in silico QSAR models evince the need of performing risk assessment for TPs as well as for the parent antimicrobial. An expert analysis of QSAR predictions using different models and degradation pathways is imperative, for a large variety of structures was found for the TPs.

Effects of ciprofloxacin on Eichhornia crassipes phytoremediation performance and physiology under hydroponic conditions

Antibiotics can be absorbed by aquatic plants, but they seriously affect the health of aquatic plants and threaten the steady state of aquatic ecosystem. The phytoremediation performance and physiology of floating macrophyte (Eichhornia crassipes) under antibiotic ciprofloxacin (CIP) hydroponic conditions were investigated. It was found that CIP absorption of E. crassipes was up to 84.38% and the root was the main absorption tissue. Hydrolysis and microbial degradation were the second removal pathway of CIP followed the plant absorption. After 7 days of CIP exposure, the photosynthesis efficiency of E. crassipes remained stable, and the presence of CIP did not inhibit the growth of the plant. On the 14th day, the superoxide dismutase and catalase activities were increased in response to the CIP stress. However, the tender leaves of E. crassipes turned white and shrivel, attributed to a decrease in chlorophyll content and chlorophyll fluorescence parameters after 21 days of CIP exposure. These findings will have significant implications for E. crassipes to absorb CIP on a limited time-scale and provide a phytoremediation technology for antibiotics in water.

A dataset of distribution of antibiotic occurrence in solid environmental matrices in China

While there is growing global concern about the impact of antibiotic residues on emergence and enhancement bacteria’s resistance, toxicity to natural organisms, and, ultimately, public health, a concise picture of measured environmental concentrations of antibiotic occurrence in multiple environmental matrices, particularly in solid matrices (e.g., sludge, soil, and sediments) is still elusive, especially for China. In this paper, we present an up-to-date dataset of the distribution of antibiotic occurrence in solid environmental matrices in China, derived from 210 peer-reviewed literature published between 2000 and 2020. We extracted geographical sampling locations and measured concentration associated with antibiotic occurrence reported in English and Chinese original publications, and applied quality-control procedures to remove duplicates and ensure accuracy. The dataset contains 6929 records of geo-referenced occurrences for 135 antibiotics distributed over 391 locations distinguished at four levels of scale i.e., provincial, prefectural, county, and township or finer. The geographical dataset provides an updated map of antibiotic occurrence in solid environmental matrices in China and can be used for further environmental health risk assessment.

Measurement(s)	Scientific Publication
Technology Type(s)	digital curation
Factor Type(s)	location • matrices • antibiotics
Sample Characteristic - Environment	solid environmental material
Sample Characteristic - Location	China

Analysis on the Dynamics of Coastline and Reclamation in Pearl River Estuary in China for Nearly Last Half Century

The Pearl River Estuary is in the geometric center of Guangdong-Hong Kong-Macao Greater Bay Area, which is one of the main battlefields to drive the high-quality development of China’s economy. This paper uses seven sets of typical satellite images in Pearl River Estuary for nearly half a century (from 1973 to 2021) to analyze the changes of coastline and sea reclamation. The results show that from 1973 to 2021, the total length of the coastline of the Pearl River Estuary increased from 240.09 km to 416.00 km, and that of the continental coastline from 186.87 km to 246.21 km (but the length of natural coastline in the continental coastline decreased from 136.91 km to 15.17 km). In the same period, the total reclamation area of the Pearl River Estuary increased by 28,256.06 ha. Before 2012, the growth rate of reclamation was generally fast. After 2012, the reclamation in China has entered a period of reflection. With reclamation was strictly controlled in the new era, only the previously approved reclamation projects and national major projects have been guaranteed, which makes the average annual growth rate of the coastline length and the reclamation area in the region show a significant downward trend. The reclamation in early days was largely for agriculture and pond culture purposes, but is shifting to transportation, industrial development, and urban construction in recent decades. This study scientifically analyzes the coastline and reclamation changes of the Pearl River Estuary in the past half century, which has a very important reference value for the next step to formulate marine ecological protection and restoration strategies, and construct a new pattern of marine space development and protection.

Antibiotic Chlortetracycline Causes Transgenerational Immunosuppression via NF-κB

The extensive and increasing global use of antibiotics results in the ubiquitous presence of antibiotics in the environment, which has made them "pseudo persistent organic contaminants." Despite numerous studies showing wide adverse effects of antibiotics on organisms, the chronic environmental risk of their exposure is unknown, and the molecular and cellular mechanisms of antibiotic toxicity remain unclear. Here, we systematically quantified transgenerational immune disturbances after chronic parental exposure to environmental levels of a common antibiotic, chlortetracycline (CTC), using zebrafish as a model. CTC strongly reduced the antibacterial activities of fish offspring by transgenerational immunosuppression. Both innate and adaptive immunities of the offspring were suppressed, showing significant perturbation of macrophages and neutrophils, expression of immune-related genes, and other immune functions. Moreover, these CTC-induced immune effects were either prevented or alleviated by the supplementation with PDTC, an antagonist of nuclear factor-κB (NF-κB), uncovering a seminal role of NF-κB in CTC immunotoxicity. Our results provide the evidence in fish that CTC at environmentally relevant concentrations can be transmitted over multiple generations and weaken the immune defense of offspring, raising concerns on the population hazards and ecological risk of antibiotics in the natural environment.

Microbial Community Structure and Bacterial Lineages Associated with Sulfonamides Resistance in Anthropogenic Impacted Larut River

Anthropogenic activities often contribute to antibiotic resistance in aquatic environments. Larut River Malaysia is polluted with both organic and inorganic pollutants from domestic and industrial wastewater that are probably treated inadequately. The river is characterized by high biochemical oxygen demand, chemical oxygen demand, total suspended solids, ammonia, and heavy metals. In our previous study, sulfonamides (SAs) and sulfonamide resistance genes (sul) were detected in the Larut River. Hence, in this study, we further examined the microbial community structure, diversity of sulfonamide-resistant bacteria (SARB), and their resistance genes. The study also aimed at identifying cultivable bacteria potential carriers of sul genes in the aquatic environment. Proteobacteria (22.4–66.0%), Firmicutes (0.8–41.6%), Bacteroidetes (2.0–29.4%), and Actinobacteria (5.5–27.9%) were the most dominant phyla in both the effluents and river waters. SARB isolated consisted only 4.7% of the total genera identified, with SAR Klebsiella as the most dominant (38.0–61.3%) followed by SAR Escherichia (0–22.2%) and Acinetobacter (3.2–16.0%). The majority of the SAR Klebsiella isolated from the effluents and middle downstream were positive for sul genes. Sul genes-negative SAR Escherichia and Acinetobacter were low (<20%). Canonical-correlation analysis (CCA) showed that SAs residues and inorganic nutrients exerted significant impacts on microbial community and total sul genes. Network analysis identified 11 SARB as potential sul genes bacterial carriers. These findings indicated that anthropogenic activities exerted impacts on the microbial community structure and SAs resistance in the Larut River.