scholarly journals Quantitative Occurrence of Antibiotic Resistance Genes among Bacterial Populations from Wastewater Treatment Plants Using Activated Sludge

2019 ◽  
Vol 9 (3) ◽  
pp. 387 ◽  
Author(s):  
Adriana Osińska ◽  
Ewa Korzeniewska ◽  
Monika Harnisz ◽  
Sebastian Niestępski

Wastewater treatment plants (WWTPs) are an important reservoir in the development of drug resistance phenomenon and they provide a potential route of antibiotic resistance gene (ARGs) dissemination in the environment. The aim of this study was to assess the role of WWTPs in the spread of ARGs. Untreated and treated wastewater samples that were collected from thirteen Polish WWTPs (applying four different modifications of activated sludge–based treatment technology) were analyzed. The quantitative occurrence of genes responsible for the resistance to beta-lactams and tetracyclines was determined using the real-time PCR method. Such genes in the DNA of both the total bacterial population and of the E. coli population were analyzed. Among the tested genes that are responsible for the resistance to beta-lactams and tetracyclines, blaOXA and blaTEM and tetA were dominant, respectively. This study found an insufficient reduction in the quantity of the genes that are responsible for antibiotic resistance in wastewater treatment processes. The results emphasize the need to monitor the presence of genes determining antibiotic resistance in the wastewater that is discharged from treatment plants, as they can help to identify the hazard that treated wastewater poses to public health.

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1516
Author(s):  
Il Han ◽  
Keunje Yoo

Wastewater treatment plants (WWTPs) have been considered hotspots for the development and dissemination of antibiotic resistance in the environment. Although researchers have reported a significant increase in bioaerosols in WWTPs, the associated bacterial taxa, antibiotic resistance genes (ARGs), and mobile genetic elements (MGEs) remain relatively unknown. In this study, we have investigated the abundance and occurrences of ARGs and MGEs, as well as the bacterial community compositions in activated sludge (AS), dewatered sludge (DS) and bioaerosols (BA) in a WWTP. In total, 153 ARG subtypes belonging to 19 ARG types were identified by the broad scanning of metagenomic profiles obtained using Illumina HiSeq. The results indicated that the total occurrences and abundances of ARGs in AS and DS samples were significantly higher than those in BA samples (p < 0.05). However, some specific ARG types related to sulfonamide, tetracycline, macrolide resistance were present in relatively high abundance in BA samples. Similar to many other full-scale WWTPs, the Proteobacteria (58%) and Bacteroidetes (18%) phyla were dominant in the AS and DS samples, while the Firmicutes (25%) and Actinobacteria (20%) phyla were the most dominant in the BA samples. Although the abundance of genes related to plasmids and integrons in bioaerosols were two to five times less than those in AS and DS samples, different types of MGEs were observed in BA samples. These results suggest that comprehensive analyses of resistomes in BA are required to better understand the emergence of both ARGs and MGEs in the wastewater treatment process due to the significant increase of scientific attention toward bioaerosols effects.


2018 ◽  
Vol 77 (7) ◽  
pp. 1810-1818 ◽  
Author(s):  
Courtney M. Gardner ◽  
Carley A. Gwin ◽  
Claudia K. Gunsch

Abstract The use of transgenic crops has become increasingly common in the United States over the last several decades. Increasing evidence suggests that DNA may be protected from enzymatic digestion and acid hydrolysis in the digestive tract, suggesting that crop-derived transgenes may enter into wastewater treatment plants (WWTPs) intact. Given the historical use of antibiotic resistance genes as selection markers in transgenic crop development, it is important to consider the fate of these transgenes. Herein we detected and quantified crop-derived transgenes in WWTPs. All viable US WWTP samples were found to contain multiple gene targets (p35, nos, bla and nptII) at significantly higher levels than control samples. Control wastewater samples obtained from France, where transgenic crops are not cultivated, contained significantly fewer copies of the nptII gene than US activated and digester sludges. No significant differences were measured for the bla antibiotic resistance gene (ARG). In addition, a nested PCR (polymerase chain reaction) assay was developed that targeted the bla ARG located in regions flanked by the p35 promoter and nos terminator. Overall this work suggests that transgenic crops may have provided an environmental source of nptII; however, follow-up studies are needed to ascertain the viability of these genes as they exit WWTPs.


2021 ◽  
Author(s):  
Ling-Dong Shi ◽  
Xiyang Dong ◽  
Zongbao Liu ◽  
Yuchun Yang ◽  
Jih-Gaw Lin ◽  
...  

Activated sludge of wastewater treatment plants harbors a very high diversity of both microorganisms and viruses, wherein the latter control microbial dynamics and metabolisms by infection and lysis of cells. However, it remains poorly understood how viruses impact the biochemical processes of activated sludge, for example in terms of treatment efficiency and pollutant removal. Using metagenomic and metatranscriptomic deep sequencing, the present study recovered thousands of viral sequences from activated sludge samples of three conventional wastewater treatment plants. Gene-sharing network indicated that most of viruses could not be assigned to known viral genera, implying activated sludge as an underexplored reservoir for new viruses and viral diversity. in silico Predictions of virus-host linkages demonstrated that infected microbial hosts, mostly belonging to bacteria, were transcriptionally active and able to hydrolyze polymers including starches, celluloses, and proteins. Some viruses encode auxiliary metabolic genes (AMGs) involved in carbon, nitrogen, and sulfur cycling, and antibiotic resistance genes (ARGs) for resistance to multiple drugs. The former group of virus-encoded genes (i.e. AMGs) may enhance the biodegradation of contaminants like starches and celluloses, suggesting a positive role for viruses in strengthening the performance of activated sludge. However, the latter group (i.e. ARGs) would be disseminated to different microorganisms using viruses as gene shuttles, demonstrating the possibility for viruses to facilitate the spread of antibiotic resistance in the environment. Collectively, this study highlights the mixed blessing of viruses in wastewater treatment plants, and deciphers how they manipulate the biochemical processes in the activated sludge, with implications for both environmental protection and ecosystem security.


2020 ◽  
Vol 10 (17) ◽  
pp. 5816
Author(s):  
Damian Rolbiecki ◽  
Monika Harnisz ◽  
Ewa Korzeniewska ◽  
Łukasz Jałowiecki ◽  
Grażyna Płaza

This study identified differences in the prevalence of antibiotic resistance genes (ARGs) between wastewater treatment plants (WWTPs) processing different proportions of hospital and municipal wastewater as well as various types of industrial wastewater. The influence of treated effluents discharged from WWTPs on the receiving water bodies (rivers) was examined. Genomic DNA was isolated from environmental samples (river water, wastewater and sewage sludge). The presence of genes encoding resistance to sulfonamides (sul1, sul2) and fluoroquinolones (qepA, aac(6′)-Ib-cr) was determined by standard polymerase chain reaction (PCR). The effect of the sampling season (summer – June, fall – November) was analyzed. Treated wastewater and sewage sludge were significant reservoirs of antibiotic resistance and contained all of the examined ARGs. All wastewater samples contained sul1 and aac(6′)-lb-cr genes, while the qepA and sul2 genes occurred less frequently. These observations suggest that the prevalence of ARGs is determined by the type of processed wastewater. The Warmia and Mazury WWTP was characterized by higher levels of the sul2 gene, which could be attributed to the fact that this WWTP processes agricultural sewage containing animal waste. However, hospital wastewater appears to be the main source of the sul1 gene. The results of this study indicate that WWTPs are significant sources of ARGs, contributing to the spread of antibiotic resistance in rivers receiving processed wastewater.


Author(s):  
Alicia Sorgen ◽  
James Johnson ◽  
Kevin Lambirth ◽  
Sandra Clinton ◽  
Molly Redmond ◽  
...  

Bacterial resistance to antibiotics is a growing global concern, threatening human and environ-mental health, particularly among urban populations. Wastewater treatment plants (WWTPs) are thought to be &ldquo;hotspots&rdquo; for antibiotic resistance dissemination. The conditions of WWTPs, in conjunction with the persistence of commonly used antibiotics, may favor the selection and trans-fer of resistance genes among bacterial populations. WWTPs provide an important ecological niche to examine the spread of antibiotic resistance. We used heterotrophic plate count methods to identify phenotypically resistant cultivable portions of these bacterial communities and charac-terized the composition of the culturable subset of these populations. Resistant taxa were more abundant in raw sewage and wastewater before the biological aeration treatment stage. While some antibiotic resistant bacteria (ARB) were detectable downstream of treated wastewater re-lease, these organisms are not enriched relative to effluent-free upstream water, indicating effi-cient removal during treatment. Combined culture-dependent and culture-independent analyses revealed a stark difference in community composition between culturable fractions and the envi-ronmental source material, irrespective of culturing conditions. Higher proportions of the envi-ronmental populations were recovered than predicted by the widely accepted 1% culturability paradigm. These results represent baseline abundance and compositional data for ARB commu-nities for reference in future studies addressing the dissemination of antibiotic resistance associ-ated with urban wastewater treatment ecosystems.


Antibiotics ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 352
Author(s):  
Alicia Sorgen ◽  
James Johnson ◽  
Kevin Lambirth ◽  
Sandra M. Clinton ◽  
Molly Redmond ◽  
...  

Bacterial resistance to antibiotics is a growing global concern, threatening human and environmental health, particularly among urban populations. Wastewater treatment plants (WWTPs) are thought to be “hotspots” for antibiotic resistance dissemination. The conditions of WWTPs, in conjunction with the persistence of commonly used antibiotics, may favor the selection and transfer of resistance genes among bacterial populations. WWTPs provide an important ecological niche to examine the spread of antibiotic resistance. We used heterotrophic plate count methods to identify phenotypically resistant cultivable portions of these bacterial communities and characterized the composition of the culturable subset of these populations. Resistant taxa were more abundant in raw sewage and wastewater before the biological aeration treatment stage. While some antibiotic-resistant bacteria (ARB) were detectable downstream of treated wastewater release, these organisms are not enriched relative to effluent-free upstream water, indicating efficient removal during treatment. Combined culture-dependent and -independent analyses revealed a stark difference in community composition between culturable fractions and the environmental source material, irrespective of culturing conditions. Higher proportions of the environmental populations were recovered than predicted by the widely accepted 1% culturability paradigm. These results represent baseline abundance and compositional data for ARB communities for reference in future studies addressing the dissemination of antibiotic resistance associated with urban wastewater treatment ecosystems.


Author(s):  
April Murphy ◽  
Daniel Barich ◽  
M. Siobhan Fennessy ◽  
Joan L. Slonczewski

Antibiotic resistance is a growing problem worldwide, with frequent transmission between pathogens and environmental organisms. Rural rivers can support high levels of recreational use by people unaware of inputs from treated wastewater, while wastewater treatment plants (WWTPs) can generate a small but significant portion of flow volume into a river surrounded by forest and agriculture.


2021 ◽  
Vol 12 ◽  
Author(s):  
Cansu Uluseker ◽  
Krista Michelle Kaster ◽  
Kristian Thorsen ◽  
Daniel Basiry ◽  
Sutha Shobana ◽  
...  

This paper reviews current knowledge on sources, spread and removal mechanisms of antibiotic resistance genes (ARGs) in microbial communities of wastewaters, treatment plants and downstream recipients. Antibiotic is the most important tool to cure bacterial infections in humans and animals. The over- and misuse of antibiotics have played a major role in the development, spread, and prevalence of antibiotic resistance (AR) in the microbiomes of humans and animals, and microbial ecosystems worldwide. AR can be transferred and spread amongst bacteria via intra- and interspecies horizontal gene transfer (HGT). Wastewater treatment plants (WWTPs) receive wastewater containing an enormous variety of pollutants, including antibiotics, and chemicals from different sources. They contain large and diverse communities of microorganisms and provide a favorable environment for the spread and reproduction of AR. Existing WWTPs are not designed to remove micropollutants, antibiotic resistant bacteria (ARB) and ARGs, which therefore remain present in the effluent. Studies have shown that raw and treated wastewaters carry a higher amount of ARB in comparison to surface water, and such reports have led to further studies on more advanced treatment processes. This review summarizes what is known about AR removal efficiencies of different wastewater treatment methods, and it shows the variations among different methods. Results vary, but the trend is that conventional activated sludge treatment, with aerobic and/or anaerobic reactors alone or in series, followed by advanced post treatment methods like UV, ozonation, and oxidation removes considerably more ARGs and ARB than activated sludge treatment alone. In addition to AR levels in treated wastewater, it examines AR levels in biosolids, settled by-product from wastewater treatment, and discusses AR removal efficiency of different biosolids treatment procedures. Finally, it puts forward key-points and suggestions for dealing with and preventing further increase of AR in WWTPs and other aquatic environments, together with a discussion on the use of mathematical models to quantify and simulate the spread of ARGs in WWTPs. Mathematical models already play a role in the analysis and development of WWTPs, but they do not consider AR and challenges remain before models can be used to reliably study the dynamics and reduction of AR in such systems.


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