[Characteristics of Antibiotic Resistance Genes Distribution in Different Types of Agricultural Land Soils in Highly Cultivated Hilly Areas]

To characterize the distribution of antibiotic resistance genes(ARGs) in different types of agricultural soil in highly cultivated hilly areas, the abundance and diversity of ARGs in vegetable, orchard, and arable soils were analyzed in this study. The results showed that 70 ARGs and four mobile genetic elements(MGEs) were detected in all soil samples, with β-lactam cphA-01 being the most abundant genes in the agricultural soils. In vegetable and orchard soils, the main ARG subtypes were cphA-01 and cmx(A) genes, whereas the mexF and aacC genes were predominant in cropland soils. The relative abundance and diversity of soil ARGs showed that cropland Collapse

Key Words

• agricultural land
• antibiotic resistance genes(ARGs)
• high-throughput QPCR(HT-QPCR)
• highly cultivated hilly areas
• mobile genetic elements(MGEs)

Collapse

MESH Headings

• Soil
• Genes, Bacterial
• Anti-Bacterial Agents/pharmacology
• Soil Microbiology
• Drug Resistance, Microbial/genetics
• Vegetables
• Manure

Collapse

Grants Collapse

[Distribution and Driving Mechanisms of Antibiotic Resistance Genes in Desert-Oasis Continuum]

The oasis agro-ecosystem is a complex ecosystem with intensive human activities in arid areas. Microbial antibiotic resistance is posing threats to human health and ecological balance. It is of great importance to investigate the diversity, distribution profiles, and driving factors of soil antibiotic resistance genes under different land use patterns in a desert-oasis continuum, especially for assessing soil environmental and human health risks in arid regions. In this study, high throughput sequencing combined with high throughput quantitative PCR were used to investigate the microbial community structure and patterns of antibiotic resistance genes in a desert-oasis continuum, aiming to explore the distribution characteristics and driving mechanisms of soil resistance genes. The results showed that the diversity and abundance of antibiotic resistance increased significantly from the edge of desert to the central oasis, along with Dest, Cotn, Maiz, Reed, and Sedt, consecutively, implying that farmland soil was an important reservoir of resistance genes, which was closely related to land use and land cover change. Soil microbial communities were significantly correlated with antibiotic resistance genes. Thiobacillus, Pontibacter, Nocardioides, Salinimicrobium, Solirubrobacter, and Streptomyces were important potential hosts of various resistance genes. The patterns of antibiotic resistance genes were shaped by heavy metal elements, MGEs, and microbial communities in arid soil, which accumulatively accounted for 70% of the variations in resistance genes alone or together and therefore drove the occurrence, enrichment, and evolution of resistance genes in agricultural soil of the desert-oasis continuum.

[Distribution Characteristics of Antibiotic Resistance Genes on Different Water Supply Pipes]

To study the distribution characteristics and horizontal transfer potential of antibiotic resistance genes in biofilms of water supply pipes made of different materials, the biofilms of 304 and 316 L stainless steel pipes and PPR and PE plastic pipes were analyzed using metagenomic sequencing. The results showed that a total of 146 antibiotic resistance genes belonging to 17 classes were detected in the biofilms. Multidrug resistance genes had the highest abundance and varied a lot in different biofilms, which was the main reason for the differences in antibiotic resistance genes in different biofilms. The total abundance of mobile genetic elements was high in different biofilms, but overall coexistence with antibiotic resistance genes was low, with integrase genes showing a closer relationship with antibiotic resistance genes and possibly playing an important role in the horizontal transfer of antibiotic resistance genes. Different antibiotic resistance genes possessed different genera of potential hosts; highly abundant hosts such as Aquabacterium and Bradyrhizobium were the basis for the presence of a high abundance of multidrug resistance genes. Microbial attachment in different pipe walls was selective, and the primary influence of antibiotic resistance in biofilms was bacterial community composition, followed by the horizontal transfer of genes mediated by mobile genetic elements, community composition, and mobile genetic elements together shaping the distribution characteristics of antibiotic resistance genes.

[Distribution Characteristics of Antibiotics and Antibiotic Resistance Genes in Manure and Surrounding Soil of Poultry Farm in Ningxia]

Antibiotics and antibiotic resistance genes (ARGs) in livestock and poultry manure pose potential ecological risks. In order to understand the distribution characteristic of antibiotics and ARGs in manure and surrounding soils of poultry farms in Ningxia, the poultry manure and relative soil samples were collected from 12 layers of different poultry breeding farms. The compositions of antibiotics and ARGs in the samples were analyzed using UPLC-MS/MS and HT-qPCR. The results showed that:① tetracycline, aminoglycoside, and sulfonamide were the dominant antibiotics in poultry manure. The types and contents of antibiotics in poultry manure were different in different breeding periods. There were more types of antibiotics in the brooding period, the average content was high, and the initial stage showed the opposite trend. ② A small amount of antibiotics was detected in the surrounding soil only 20 m away from the poultry farm, and the poultry farm had little effect on the distribution of antibiotics in the surrounding soil. The content of quinolone in the soils with poultry manure application was significantly higher than that in the control and surrounding soil. ③ We detected 132-168 ARGs in poultry manure, and the number of aminoglycosides and tetracycline was higher. The relative abundance of ARGs in the rearing period was highest, and the initial stage showed the opposite trend. The total relative abundance of ARGs in the brooding period was highest, but the terminal period showed the opposite. There were 110 ARGs in poultry manure during all breeding periods. ④ There were 23-105 ARGs in the soils, and the number of aminoglycoside was highest, followed by multidrug ARGs. The poultry farm had a great effect on the number and relative abundance of ARGs in the surrounding soil. For example, the number and relative abundance of ARGs in the surrounding soil of poultry farms gradually decreased with the increase in the distance from the poultry farms. The number and relative abundance of ARGs in the soil with applied poultry manure were significantly increased; however, these values were lower than those in the soil 20 m away from the poultry farm. ⑤ β-lactamases, aminoglycosides, and macrolide lincosamide-streptogramin B (MLSB) ARGs were all at risk of horizontal movement in manure, and chloramphenicol ARGs were at risk of horizontal movement in soil. Correlation analysis showed that the relative abundance of aminoglycoside, tetracycline, sulfonamide, β-lactamase, and MLSB were not significantly correlated with their contents. ⑥ Different types of ARGs had related co-occurrence phenomena, such as the positive correlation between the relative abundance of ARGs in poultry manure, and aminoglycoside and β-lactamases, MGEs, multidrugs and vancomycins. The relative abundances of ARGs in soil, aminoglycoside and tetracyclines, vancomycins, sulfonamides, and MLSBs; tetracyclines and MLSBs; etc., all showed a significant positive correlation. In short, the co-occurrence among the relative abundance of ARGs in soil was significantly stronger than that in poultry manure. These results could provide the theoretical basis for the site selection of poultry farms, the selection of antibiotic types and dosages for large-scale breeding of laying hens, and the application of poultry manure.

[Correlation Analysis among Environmental Antibiotic Resistance Genes Abundance, Antibiotics Concentrations, and Heavy Metals Concentrations Based on Web of Science Searches]

Antibiotics and heavy metals are both important environmental pollutants and selective stressors for antibiotic resistance. However, the impact of their environmental concentrations on antibiotic resistance levels is still unclear. In this paper, research published before 2019 reporting the abundance of antibiotic resistance genes(ARGs), antibiotics concentrations, or heavy metal concentrations were extracted from the Web of Science database, and then statistical regression was used to investigate their correlative association. The results show that antibiotic selection pressure has a statistically significant effect on the increase in the abundance of ARGs in environmental media such as surface water, sediment, and soil, even at very low antibiotic concentrations(P<0.05). Different classes of antibiotics show different potential to select and enrich ARGs. Heavy metals and the interaction between antibiotics and heavy metals also have significant effects on ARG transmission(P<0.05). Multivariate statistical regression models can better explain the variance of ARG abundance, with R² values for the water phase and solid phase environmental samples of 0.482 and 0.707 respectively, which are much higher than those achieved using univariate regression models. However, additional environmental factors not included may also affect ARG abundance. The results of this work provide a basis for the evaluation and control of environmental antibiotic resistance.

[Distribution and Removal of Antibiotic-Resistant Bacteria and Antibiotic Resistance Genes in Petrochemical Wastewater Treatment Plants]

A petrochemical wastewater treatment plant (PWWTP) was selected to investigate the distribution and removal of antibiotic-resistant bacteria (ARB) and three forms of antibiotic resistance genes (ARGs), namely intracellular ARGs (iARGs), adsorbed-extracellular ARGs (aeARGs), and free extracellular ARGs (feARGs). Tetracycline, sulfanilamide, and ampicillin ARB were detected with the total absolute concentration of 8.45×10²-2.38×10⁵ CFU·mL^-1; the absolute concentrations of three types of ARB decreased by 0.04 lg-0.21 lg through anaerobic treatment. The effect of aeration and precipitation treatment on ARB varies with its type, and the absolute concentration of ARB in effluent was 0.12 lg-0.63 lg higher than that in influent. The absolute abundance of aeARGs and iARGs in activated sludge was 1.96×10⁷-3.02×10¹⁰ copies·g^-1 and 5.22×10⁷-4.15×10¹⁰ copies·g^-1, respectively; the absolute abundance of feARGs in wastewater was 5.90×10⁸-1.01×10¹² copies·L^-1. Anaerobic treatment can remove 0.13 lg-0.65 lg aeARGs and 0.04 lg-0.28 lg iARGs, while the removal efficiency of aeARGs and iARGs by aeration and precipitation process was affected by ARGs types and forms. The absolute abundance of feARGs in effluent is 0.06 lg-0.81 lg higher than that in influent. Redundancy analysis showed that the concentration of ARB was significantly positively correlated with chemical oxygen demand (COD), Cl^-, and total nitrogen concentration (P<0.05). The abundance of aeARGs was positively correlated with COD and total nitrogen concentration (P<0.05), and both the abundance of iARGs and feARGs are positively correlated with heavy metals concentration (P<0.05). This study confirmed the enrichment risk of ARB and different forms of ARGs in PWWTPs, which provided references for the research and prevention of antibiotic resistance pollution in industrial wastewater.

[Effects of Temperature and Stirring on the Changes of Antibiotic Resistance Genes and Microbial Communities in Anaerobic Digestion of Dairy Manure]

To investigate the effects of temperature and stirring on antibiotic resistance genes (ARGs) and microbial communities during the anaerobic digestion of dairy manure, mesophilic and thermophilic anaerobic digestion experiments were performed with and without stirring. Two-way analysis of variance indicated that temperature affected biogas production more strongly than stirring (η²=0.934>0.911), and thermophilic and stirring increased the total biogas yield by 13.93% and 12.63%, respectively. The effect of temperature on the removal of ARGs was also stronger than that of stirring (η²=0.992>0.920), where thermophilic conditions enhanced the reduction of ARGs and MGEs to 0.09-1.53 (logarithm), while stirring had no significant effects. When temperature was altered from mesophilic to thermophilic, the microbial communities shifted, with Firmicutes becoming the dominant phylum after thermophilic anaerobic digestion, with a relative abundance of >86%. Network analysis demonstrated that eight genera including Sedimentibacter, Sphaerochaeta, and Pseudomonas were the hosts of ARGs and MGEs, and the redundancy analysis suggested that physicochemical parameters play important roles in shaping microbial communities, especially TAN and TVFAs, which indirectly affected the ARGs by altering their host bacteria.

[Abundance Change of Antibiotic Resistance Genes During PDWW Recycling and Correlations with Environmental Factors]

Research on the distribution of antibiotic resistance genes (ARGs) in urban sewage treatment systems is extensive, but there is still insufficient research on their abundance in industrial wastewater recycling systems. In this study, a printing and dyeing wastewater (PDWW) recycling system was constructed, and 16S rDNA and high-throughput sequencing technology was used to analyze the microbial communities and ARG abundance during the treatment process. A total of 52 ARGs in nine categories were detected, of which the relative abundance of β-lactam resistance genes was the highest. During the treatment cycle, the concentration of aromatic pollutants increased with an increase in the number of cycles, while the abundance of β-lactam resistance genes increased first, decreased, and then increased (reaching 61.85% on the 100th day). At the same time, the abundance of Firmicutes, Actinobacteria, and Cyanobacteria related ARGs decreased significantly (by 84.66%, 64.38%, and 85.15%, respectively). More than 21 kinds of ARGs were significantly affected by the enrichment by the aromatic pollutants. Among them, 6 kinds of ARGs were significantly positively correlated with changes in the concentrations of the aromatic pollutants (P<0.01), while 6 were significantly negatively correlate (P<0.01). These results show that the abundance of ARGs was affected by the microbial communities and the aromatic pollutants, which increased at first, decreased, and then increased during the PPDW recycling process. This study reveals the effects of the enrichment of aromatic contaminants and changes in microbial communities on ARGs during PPDW recycling, and provides theoretical guidance for the recycling of PDWW to reduce environmental pollution associated with ARGs.

[Distribution Characteristics of Antibiotics and Antibiotic Resistance Genes in Manure and Surrounding Soil of Cattle Farms in Ningxia]

Livestock breeding intensively uses veterinary antibiotics in concentrated feeding operations to improve growth and control disease. Consequently, livestock and poultry manure is an important repository of antibiotics and antibiotic resistance genes (ARGs). To understanding the distribution of antibiotics and ARGs in manure and surrounding soils of cattle farms in Ningxia, cattle manure from five breeding periods (lactation, calving, growing, pre-fattening, and post-fattening periods) and comparative soil samples were collected from the largest beef-breeding area in Ningxia. The compositions of ARGs in the samples were analyzed by UPLC-MS/MS and HT-qPCR. The results showed that:① Tetracycline, quinolone, and sulfonamide were the dominant antibiotics in cattle manure. The content of antibiotics in the manure varied greatly between different breeding periods. High amounts of antibiotics were detected during the pre-fattening and lactation periods, and the lowest amounts were detected during the calving period. ② Quinolone and tetracycline were the dominant antibiotics in the soils, and the detection rate and content of quinolone were highest. The cattle farms did not affect the distribution of antibiotics in the surrounding soils. The content of quinolone and tetracycline in the soils with cattle manure application were significantly higher than control and surrounding soils. ③ We detected 79-142 ARGs in cattle manure, with aminoglycosides the most common form. The number and relative abundance of ARGs were highest during the growing period and lowest during the calving period. The dominant ARGs were tetQ, ermF, and tetO-01 across all the breeding periods. ④ There were 35-79 ARGs in the tested soils, and multidrug and aminoglycoside ARGs were dominant. The cattle farms did not affect the number and relative abundance of ARGs in the surrounding soils; however, manure application significantly affected the number and relative abundance of ARGs. ⑤ Sulfonamide and chloramphenicol ARGs are at risk of mobilization and horizontal transport. A correlation analysis showed that the relative abundances of aminoglycoside and tetracycline in cattle manure were significantly positively correlated with their contents. ⑥ Aminoglycoside, sulfonamide, chloramphenicol, and mobile genetic elements (MGEs) in manure were significantly or extremely significantly positively correlated with aminoglycosides and sulfonamides in the soils, whereas macrolides were negatively correlated with vancomycin. These results provide baseline data to inform controls on the variety and dosages of feed and veterinary drugs in cattle farms and the application of organic fertilizers in agriculture.

[Distribution Characteristics of Antibiotics and Antibiotic Resistance Genes in Wastewater Treatment Plants]

Antibiotics and antibiotic resistance genes (ARGs) are highly concerning emerging polltants. Wastewater treatment plants (WWTPs) are considered to be one of the most important anthropogenic sources of antibiotics and ARGs in the environment. Six WWTPs of a city were selected to investigate the antibiotics and ARGs in the influents and effluents, respectively. In total, 73 kinds antibiotics belonging to 7 classes were detected in WWTPs. The total concentration of those antibiotics ranged between 490.2-2288.6 ng·L^-1, and ofloxacin, maprofloxacin, and roxithromycin were the most frequently detected antibiotics in the influents. A dramtic difference was observed in the antibiotic removal efficiency among the WWTPs, and the total antibiotic concentration in the effluents ranged between 260.2-1464.3 ng·L^-1. Macrolides and quinolones are the main classes in the effluents, and the antibiotic concentration in the effluents was higher than that in the influents. Ten kinds of ARGs were detected in the WWTPs. Among these, sul Ⅰ was the most widely prevalent with an absolute abundance of 2.4×10⁵-5.4×10⁶ copies·mL^-1. No significant difference in ARG abundance was observed between industrial wastewater and domesic wastewater. Furthermore, the correlation between ARG abundance and antibiotic concentrations weakened after treatment in the WWTPs.

[Microplastics-Induced Shifts of Diversity and Abundance of Antibiotic Resistance Genes in River Water]

Microplastics (MPs) and antibiotic resistance genes (ARGs) are both considered emerging contaminants of increasing concern because their combined pollution poses a serious risk to the ecological environment and human health. In this study, high-throughput quantitative PCR techniques were used to investigate the diversity and abundance of ARGs in river water, to which two different microplastics (PVC and PVA) were added for aerated incubation. The results showed that ARGs in river water were diverse, and microplastics could induce more types of ARGs. Although the number and abundance of ARGs decreased in all three treatments, which were cultivated for 14 d by aeration, compared to those in non-treated samples, the total abundance of ARGs in treatments aerated with MPs were higher than those aerated without MPs, especially in the samples treated with water-soluble microplastics (PVA). Significant correlations between the abundance of ARGs and mobile genetic elements (MGEs) were observed, implying that the occurrence of MGEs may potentially affect the transmission and distribution of ARGs through horizontal gene transfer (HGT) in river water.

[Distribution Characteristics of Antibiotic Resistance Genes and Mobile Genetic Elements in Beijing Vegetable Base Soils]

The distribution characteristics of antibiotic resistance genes (ARGs) and mobile genetic elements (MGEs) in five vegetable base soils from Beijing, China, were assessed. The composition of ARGs and MGEs in soil samples were analyzed by HT-qPCR. We detected 92-121 ARGs and 4-6 MGEs. The ARGs and MGEs in vegetable base soils from different districts were separated from each other. The dominant ARGs shared by vegetable bases were oprD, acrA-04, and acrA-05 of a multidrug, mphA-01 of MLSB, and β-Lactamase fox5, vanC-03 of vancomycin. The shared MGE among the five vegetable base soils was intI1. A total of seven antibiotics were detected in the soil of several vegetable bases. The dominant antibiotics included enoxacin (ENR), norfloxacin (NOR), oxytetracycline (OTC), and sulfamethoxazole (SMX). The numbers and abundance of antibiotics in the soil of vegetable bases from the Shunyi district were the highest, followed by those from Tongzhou and Changping. Correlation analysis showed that there was a significant positive correlation between the abundance of ARGs and the abundance of antibiotics in the soil of vegetable bases (P<0.05). These results provide basic theoretical data for controlling the transmission of ARGs.

[Metagenomic Analysis of Antibiotic Resistant Bacteria and Resistance Genes in a Pharmaceutical and Chemical Wastewater Treatment Plant]

Wastewater treatment plants hold a vast pool of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs). The aim of this study is to analyze the ARB and ARGs in a pharmaceutical and chemical wastewater treatment plant using a metagenomic technique. The results of taxonomic annotation revealed that bacteria were the predominant domain. The most abundant phyla and genus was Proteobacteria and Hyphomicrobium, respectively. A total of 74 categories of ARGs were predicted using CARD with the most dominant types being sav 1866, dfrE, and mfd. Furthermore, a network analysis was conducted to investigate the co-occurrence patterns between ARGs and microbial taxa. ARGs were found to be highly connected to microbial taxa at the genus level. With respect to the antibiotic resistance mechanisms, antibiotic-specific efflux pumps appeared to be the most common mechanisms. Among these, resistance-nodulation-cell division (RND) was the major type. The most important functional pathway of this microbial community was metabolic correlation. Interestingly, there were many genes related to human diseases, among which bacterial infectious diseases were the main ones. On the one hand, these data further confirmed that pharmaceutical and chemical wastewater treatment plants are rich in ARB and ARGs. The accumulation of ARGs increases the potential environmental risks, and hence it is necessary to strengthen the active monitoring of ARB and ARGs in pharmaceutical and chemical wastewater treatment plants. On the other hand, research on ARB and ARGs offers important information for the selection of deep processing technology to effectively remove ARB and ARGs.

[Distribution Characteristics of Antibiotic Resistance Genes in Wastewater Treatment Plants]

Wastewater treatment plants (WWTPs) are regarded as the main source for antibiotic resistant genes (ARGs). To explore the features regarding the distribution of ARGs in wastewater with complicated composition in treatment plants, wastewater samples from a chemical industry park that produced antibiotics were selected. qPCR was applied to detect the type and abundance of ARGs in the wastewater flows from the WWTPs. The results indicated that 16 types of ARGs were detected from the wastewater from the WWTPs, among which sulfonamide resistance genes and tetracycline resistance genes were the dominant ARGs that appeared in the wastewater. Additionally, intI 1 was detected and its abundance was correlated with that of sulfonamide resistance genes. This indicated that intI 1 may promote the migration and transformation of sulfonamide resistance genes. The pharmaceutical factories in the park mainly synthesize macrolide antibiotics. Because of the selective pressure, the absolute abundance of ermB in the wastewater was much higher than that in the other industrial wastewater. The total ARGs decreased by 1.16 log via traditional biological treatment process, and the total ARGs decreased by 2.46 log via the Fenton process. The results showed that the removal effects of deep treatment processes on ARGs were better than that of biological treatment in this wastewater treatment process. Highly abundant and movable ARGs already exist in the water body, and their release from WWTPs without effective treatment poses high risks to the environment.

[Effects of Microplastics on Antibiotic Resistance Genes in Estuarine Sediments]

Microplastics and antibiotic resistance genes (ARGs) are emerging pollutants/contaminants, and are also the research hotspots concerning environmental health in the past few years. To explore the effects of microplastics on ARGs in estuarine sediment, three different microplastics were added to microcosm incubation experiments of sediments. Then, we investigated the persistence, abundance, diversity, and shifts of the ARGs in estuarine sediments by high-throughput quantitative polymerase chain reaction (PCR). The results showed that the microplastics significantly changed the structure of ARGs in the sediments. PVC and PE, which are hard to degrade, had significant effects on the structures and types of ARGs. However, the PVA, which is soluble, reduced the types and persistence of ARGs significantly. The abundance of ARGs in S_PVC, S_PE, and S_PVA were 4.1×10⁹, 8.1×10⁹, and 2.0×10⁹ copies·g^-1, respectively. The abundance of ARGs in sediments with added PE almost increased by one order of magnitude, implying that microplastics could significantly increase the abundance of ARGs in sediments. Furthermore, OLS regression analysis showed that ARGs are significantly correlated with transposon and integron, suggesting that mobile genetic elements (MGEs) may promote the transfer and dissemination of ARGs.