Submitted Successfully!
To reward your contribution, here is a gift for you: A free trial for our video production service.
Thank you for your contribution! You can also upload a video entry or images related to this topic.
Version Summary Created by Modification Content Size Created at Operation
1 -- 2064 2023-03-20 10:15:24 |
2 Fix an error + 515 word(s) 2579 2023-03-20 10:25:35 | |
3 format correct Meta information modification 2579 2023-03-21 01:41:09 | |
4 format correct + 6 word(s) 2585 2023-03-21 01:42:41 | |
5 format correct Meta information modification 2585 2023-03-21 01:51:53 |

Video Upload Options

Do you have a full video?


Are you sure to Delete?
If you have any further questions, please contact Encyclopedia Editorial Office.
Wang, H.; Du, D.; Ding, Y.; Zhang, K.; Zhi, S. Plant Ecological Treatment Technology for Livestock Wastewater. Encyclopedia. Available online: (accessed on 25 June 2024).
Wang H, Du D, Ding Y, Zhang K, Zhi S. Plant Ecological Treatment Technology for Livestock Wastewater. Encyclopedia. Available at: Accessed June 25, 2024.
Wang, Han, Delin Du, Yongzhen Ding, Keqiang Zhang, Suli Zhi. "Plant Ecological Treatment Technology for Livestock Wastewater" Encyclopedia, (accessed June 25, 2024).
Wang, H., Du, D., Ding, Y., Zhang, K., & Zhi, S. (2023, March 20). Plant Ecological Treatment Technology for Livestock Wastewater. In Encyclopedia.
Wang, Han, et al. "Plant Ecological Treatment Technology for Livestock Wastewater." Encyclopedia. Web. 20 March, 2023.
Plant Ecological Treatment Technology for Livestock Wastewater

After antibiotics are used in livestock and poultry, on the one hand, selection pressure will be formed to make the intestinal microorganisms of livestock and poultry develop resistance, thus making livestock and poultry manure carry a large amount of antibiotic resistance gene (ARG); on the other hand, about 30-90% of antibiotics will be discharged into the environment with livestock and poultry manure, and the antibiotics entering the environment will not only cause chemical pollution, but most importantly, may induce antibiotic-resistant bacteria (ARB) and ARG in the environment generation in the environment. The sources of ARGs in livestock wastewater may be threefold: (1) livestock wastewater receives ARGs already present in livestock manure; (2) pollutants such as antibiotics and heavy metals in wastewater induce microorganisms to produce ARGs; and (3) proliferation of microbial host bacteria leads to proliferation of ARGs. Unlike traditional chemical pollutants, which exhibit unique environmental behaviors such as replicability, transmissibility, and environmental persistence due to their inherent biological properties, ARGs are promoted by mobile genetic elements such as plasmids, transposons, integrons, insertion sequence common regions, and complex integrons. These ARGs are transmitted between different microorganisms in environmental media through horizontal gene transfer (HGT) mechanisms and may enter the food chain and humans through direct or indirect routes, increasing human drug resistance and endangering human public health.

plant antibiotic root ARGs

1. Effectiveness of Plant Ecological Treatment Technology on the Removal of Antibiotic Resistance Genes

Plant ecological treatment technology is gradually gaining popularity; therefore, more and more scholars are suggesting to use this technology for decentralized wastewater treatment systems [1]. Up until now, many valuable conclusions have been obtained by different researchers regarding the removal of antibiotic resistance genes (ARGs) (see Table 1). For example, Ávila et al. [2] established two ecological techniques for plant treatment, and the results showed good removal efficiencies for all five target ARGs: 46% to 97% for sul1, 33% to 97% for sul2, 9% to 99% for ermB, 18% to 97% for qnrS, and 11% to 98% for blaTEM. Chen et al. [3] used an Cyperus alternifolius L. constructed ecosystem to treat domestic wastewater, and the results showed that the removal rates of 18 target ARGs ranged from 50.0% to 85.8%. Du et al. [4] used rutabaga to treat pig farm wastewater, and the results showed that the average of sulI, sulII, sulIII, tetM, tetO, and tetW removal rates were 67.5%, 85.6%, 95.6%, 87.9%, 97.9%, and 98.5%, respectively. However, the action of plants on ARGs is selective, and ARGs of different mechanisms show different behavioral convergence during the same treatment, while the same ARGs may also show different extinction patterns in ecosystems of different plant types. For example, Chen [5] showed that, after Cyperus alternifolius L. treatment, the abundance of tetO and tetX in wastewater appeared to be enriched with a removal rate of −63.8% and −26.3%, respectively, while all other classes of ARGs showed better removal effects. The reason for this difference could be the different mechanisms of action or the transmission of resistance genes. For example, tetM is one of the most common tetracycline ARGs [6] which has been shown to possess the broadest bacterial host range [7], and it is usually associated with chromosomes, conjugates, and transposons of the Tn1545-916 family; therefore, tetM is ubiquitous in many systems and is widely disseminated in the environment, whereas tetO genes are mobile only on binding plasmids [8], which are theoretically less transmissible than tetM. Therefore, studying the mechanism of action specific to ARGs in combination with plant physiological properties will not only help enrich the knowledge of ARG removal mechanisms but also contribute to the sustainable development of the whole ecological treatment technology.

2. Drivers of Resistance Gene Elongation in Plant Ecological Treatment Systems

In terms of microenvironment, there are various factors that influence the behavioral attribution of ARGs during plant treatment of wastewater; microbial communities, mobile genetic elements, environmental factors, and other pollutants are closely related to changes in resistance genes. Indirect driving factors include socioeconomic and environmental factors that influence the use and dissemination of antibiotics and the development of antibiotic resistance. For example, most studies concluded that microorganisms are the host bacteria of ARGs and the growth and reproduction of microorganisms directly affect the changes in the abundance of ARGs [16]. Mobile genetic elements (MGEs) are important indicator elements for the horizontal transfer of ARGs among bacteria, and MGEs are closely related to ARG transmission. Other pollutants (antibiotics, heavy metals, etc.) and environmental factors (TN, TP, TOC, pH, etc.) can directly or indirectly affect the structure of microbial communities in wastewater treatment systems, thus affecting the changes in ARGs [17]. Currently, many studies have focused on the role of different factors in influencing changes in ARGs. For example, Zhu et al. [18] showed that microbial community structure explained 52.3% of the variation in ARGs, while MGEs explained only 7.8%. Researchers recently showed [19] that MGEs within different systems explained most (>50%) of the ARGs, followed by microbial communities. In addition, antibiotic residues can also contribute to the horizontal spread of ARGs [20], but some studies have shown that antibiotics (OTC) have a weak effect on the distribution of ARGs in lettuce tissues, accounting for only 6.3% of the total variance, but significantly correlated with tetW, ermF, sul1, and intI1 (p < 0.05) [17]. Heavy metals (Cu, Zn, Cd, etc.) also induce the production and enrichment of ARGs and have a synergistic induction with antibiotics [21][22]. In turn, other environmental factors can act directly on microorganisms, thus indirectly influencing the dynamic pattern of ARGs [19]. Feng et al. [13] investigated the relationship between soluble organic matter (DOM) and ARG removal and showed that the removal rate of DOM was significantly correlated (p < 0.001) with the removal rate of ARGs during the purification of swine farm wastewater by Acorus calamus, but the removal rate of tetW was not significantly correlated with the removal rate of DOM. Thus, it is evident that determining the driving effect of each factor on ARGs is a hot topic of current research, and the conclusions for the driving effect of each factor on ARGs within different ecosystems vary.
From a macroscopic point of view, process conditions also influence the extinction pattern of ARGs, and, currently, many researchers have examined different process conditions for plant ecological treatment technologies. Direct driving factors conclude wastewater treatment processes such as activated sludge, biological nutrient removal, and membrane bioreactors. Operational parameters such as hydraulic retention time, temperature, and pH can also affect the removal of ARGs and chemical factors. For example, the presence of heavy metals. Moreover, plant type and filler type have a direct effect on ARG removal. Chen et al. [3] compared the removal effect of Thalia dealbata Fraser. and Iris tectorum Maxim. on 11 ARGs in wastewater through comparative experiments and pointed out that plant type significantly influenced ARG removal. Feng et al. [13] showed that dissolved oxygen has a significant effect on the removal efficiency of the whole plant ecological treatment process; therefore, aeration of the water body is favored by many researchers [9], but some studies have shown that increasing the oxygen capacity does not significantly contribute to the removal of ARGs [4]. The influent method can directly affect the degree of contact between the effluent and the plants and the turbulent flow pattern of the effluent within the system, thus influencing the overall pollutant removal [8][10]. In addition, hydraulic retention time and hydraulic loading are important factors in controlling the removal of pollutants from plant ecosystem effluent, and increasing the hydraulic retention time increases the contact time between pollutants and substrate biofilm, which theoretically contributes to the removal of ARGs [5]; however, excessive hydraulic retention time can lead to an increase in the overall process footprint.
From the above analysis, it can be seen that there are many factors affecting the removal rate of ARGs, and each factor interacts with each other. As shown in Figure 1, all process conditions can be considered as macro factors, and the setting of process conditions directly affects the parameters within the system (considered as micro factors), which theoretically cannot have significant effects on macro factors and therefore can be called “weak effects”. Macro factors ultimately affect ARGs by influencing micro factors. Macro and micro factors such as policy and regulatory frameworks, technological innovations, and funding and investment can also affect the development and implementation of wastewater treatment technologies and the capacity of communities and countries to address the challenge of antibiotic resistance. Therefore, it is not only necessary to clarify the influence of individual factors on ARGs but also to integrate the interactions between various factors in order to find the main factors affecting ARG removal.
Figure 1. Relationship diagram of different driving factors.

3. Transmission Pathways and Distribution Characteristics of Antibiotic Resistance Genes in Plant Tissues

Throughout the ecological treatment system based on plant uptake, plants play a crucial role in the extinction of ARGs, and the fugitive values of ARGs within different plant tissues determine the risk and probability of ARG transmission to the next level of the food chain. The distribution characteristics of ARGs within plant tissues are a hot topic of research within the ecological transformation system. Notably, many studies have shown that ARGs can be distributed in plant tissues such as roots, stems, and leaves. For example, Yang et al. [23] showed that the plant tissues of celery, cabbage, and cucumber contained culturable bacteria resistant to cefadroxil after cefadroxil selection pressure was applied to the plant growth environment in various tissue sites of plants. The size order was soil samples > leaf peripheral samples > root endophyte samples > leaf endophyte samples. However, not all ARGs can migrate through the plant root system to all tissues of the plant. For example, Duan et al. [17] showed that sul1, sul2, ermF, and ermX can migrate from the root endophyte to the leaf part of lettuce, but tetracycline ARGs were very low in the leaf part, where tetW was not detected in the stem and leaf tissues. However, Ye et al. [24] showed that sulfonamide resistant bacteria or resistance genes (sul1 and sul2) were not detected in new lettuce leaf tissues, while they were detected in old leaf tissues (10–7 to 10–9 copies/16S copies). This shows that ARGs are unevenly distributed in different parts of the plant; moreover, different species of ARGs have different distribution characteristics.

4. Mechanism of Removal of Antibiotic Resistance Genes

ARGs, as an emerging pollutant, exhibit a different behavior and fate in different plant ecological treatment systems in terms of species and abundance. A schematic diagram about the removal mechanism of ARGs within the whole plant ecological treatment system is shown in Figure 2. Overall, the removal pathways of ARGs in plant ecological treatment systems include the following three aspects: (1) Biological role: Microorganisms play an important and complex role in ARG removal because they are not only related to the propagation and proliferation of ARGs but may also play a role in degrading ARGs [25][26]. Chen et al. [3] showed that the process of reflectant domestic wastewater microorganisms play a major role in ARG removal (73.7–95.2%). (2) Substrate sorption: Substrate sorption also plays an important role in ARG removal, and the abundance of ARGs in substrate materials showed accumulation in different plant treatment processes, which indicates that substrate materials can sorb ARGs from wastewater to achieve ARG removal [3][11]. Chen et al. [9] clearly pointed out that substrate sorption and microbial degradation are the two main mechanisms of action for ARG removal. (3) Plant uptake: Plant uptake is also an aspect of ARG removal that cannot be neglected. Studies have shown that plant tissues are not completely immune to ARGs and plant root endophytes can acquire some ARGs from root surface stomata and mechanical damage and spread them with plant endophytes so that ARGs reach the stems and leaves [27]. Although some studies have shown that microbial degradation plays a relatively large role in ARG removal while substrate sorption and plant uptake play a relatively small role [3], the role of the latter two is inextricably linked to microbial degradation, and the substrate and plant root system can provide attachment sites for pollutants (ARGs) and microorganisms, thus allowing the microorganisms to more fully contact the pollutants and achieve a better degradation effect [3]. In particular, inter-root microorganisms specific to plant roots may also be important for the removal of ARGs [28][29]. Plant root surface tissue secretions, which regulate root surface pH and redox conditions, provide suitable growth conditions for interfacial microorganisms and also increase microbial activity, thus enhancing the overall biodegradation process.
Figure 2. Schematic diagram of the removal mechanism of ARG.
The question of how endophytic bacteria acquire ARG and how ARG spread between plant tissues has been a difficult research question. Many studies have shown a large overlap between the endophytic communities of plant tissues and the microbial communities in the peripheral environment of the root system [18][30][31] suggesting that the microbial community composition of plants (especially in root tissues) is largely influenced by the microbial communities of the external environment; however, for parts such as leaves far from the root tissue, the microbial communities differ from those of endophytic bacteria in the root system are even greater. For example, Zhang et al. [32] showed that only 12 bacterial OTUs (group II) in the root microbial community may spread further into the leaf endophytes, suggesting differences with the microbial community of the leaf endophytes. Furthermore, this microbial dispersal ability directly affects the probability of ARG spread. For example, Duan et al [17] showed that the thick-walled phylum Thick-walled Bacteroides (potential host bacteria for ARG) are unable to migrate from the root system to the stem and leaf tissue, which may be the main reason why tetW cannot migrate to the stem and leaf parts. Other studies have also shown that the external environment can serve as a seed bank for microbial communities within the root system and that plant endophytes are mostly acquired from the external environment at the horizontal level rather than being vertically transmitted from parental plants via seeds or pollen [33][34]. Therefore, it is important to clarify whether ARGs migrate from the effluent of P. floxima to the rhizosphere. If such a migration exists, do ARGs migrate between different tissues of floating duckweed? If so, how do they migrate and spread? Clarifying these questions is a bottleneck for controlling the spread of ARGs to the next level of the food chain and can help inform the control of secondary spread of ARGs and the assessment of the risk of ARGs entering the food chain.


  1. García, J.; García-Galán, M.J.; Day, J.W.; Boopathy, R.; White, J.R.; Wallace, S.; Hunter, R.G. A review of emerging organic contaminants (EOCs), antibiotic resistant bacteria (ARB), and antibiotic resistance genes (ARGs) in the environment: Increasing removal with wetlands and reducing environmental impacts. Bioresour. Technol. 2020, 307, 123228.
  2. Ávila, C.; García-Galán, M.J.; Borrego, C.M.; Rodríguez-Mozaz, S.; García, J.; Barceló, D. New insights on the combined removal of antibiotics and ARGs in urban wastewater through the use of two configurations of vertical subsurface flow constructed wetlands. Sci. Total Environ. 2021, 755, 142554.
  3. Chen, J.; Ying, G.G.; Wei, X.D.; Liu, Y.S.; Liu, S.S.; Hu, L.X.; He, L.Y.; Chen, Z.F.; Chen, F.R.; Yang, Y.Q. Removal of antibiotics and antibiotic resistance genes from domestic sewage by constructed wetlands: Effect of flow configuration and plant species. Sci. Total Environ. 2016, 571, 974–982.
  4. Du, L.; Zhao, Y.; Wang, C.; Zhang, H.; Chen, Q.; Zhang, X.; Zhang, L.; Wu, J.; Wu, Z.; Zhou, Q. Removal performance of antibiotics and antibiotic resistance genes in swine wastewater by in-tegrated vertical-flow constructed wetlands with zeolite substrate. Sci. Total Environ. 2020, 721, 137765.
  5. Chen, J.; Wei, X.D.; Liu, Y.S.; Ying, G.G.; Liu, S.S.; He, L.Y.; Su, H.C.; Hu, L.X.; Chen, F.R.; Yang, Y.Q. Removal of antibiotics and antibiotic resistance genes from domestic sewage by constructed wetlands: Optimization of wetland substrates and hydraulic loading. Sci. Total Environ. 2016, 565, 240–248.
  6. Huang, X.; Liu, C.; Li, K.; Liu, F.; Liao, D.; Liu, L.; Zhu, J.; Liao, J. Occurrence and distribution of veterinary antibiotics and tetracycline resistance genes in farmland soils around swine feedlots in Fujian Province, China. Environ. Sci. Pollut. Res. 2013, 20, 9066–9074.
  7. Gao, P.P.; Mao, D.Q.; Luo, Y.; Wang, L.; Xu, B.; Xu, L. Occurrence of sulfonamide and tetracycline-resistant bacteria and resistance genes in aqua-culture environment. Water Res. 2012, 46, 2355–2364.
  8. Liu, L.; Liu, Y.; Wang, Z.; Liu, C.X.; Huang, X.; Zhu, G.F. Behavior of tetracycline and sulfamethazine with corresponding resistance genes from swine wastewater in pilot-scale constructed wetlands. J. Hazard. Mater. 2014, 278, 304–310.
  9. Chen, J.; Deng, W.J.; Liu, Y.S.; Hu, L.X.; He, L.Y.; Zhao, J.L.; Wang, T.T.; Ying, G.G. Fate and removal of antibiotics and antibiotic resistance genes in hybrid constructed wetlands. Environ. Pollut. 2019, 249, 894–903.
  10. Ma, J.; Cui, Y.; Li, A.; Zou, X.; Ma, C.; Chen, Z. Antibiotics and antibiotic resistance genes from wastewater treated in constructed wetlands. Eco-Log. Eng. 2022, 177, 106548.
  11. Liu, L.; Liu, C.; Zheng, J.; Huang, X.; Wang, Z.; Liu, Y.; Zhu, G. Elimination of veterinary antibiotics and antibiotic resistance genes from swine wastewater in the vertical flow constructed wetlands. Chemosphere 2013, 91, 1088–1093.
  12. Liu, L.; Xin, Y.; Huang, X.; Liu, X. Response of antibiotic resistance genes in constructed wetlands during treatment of livestock wastewater with different exogenous inducers: Antibiotic and antibiotic-resistant bacteria. Bioresour. Technol. 2020, 314, 123779.
  13. Feng, L.; Wu, H.; Zhang, J.; Brix, H. Simultaneous elimination of antibiotics resistance genes and dissolved organic matter in treatment wetlands: Characteristics and associated relationship. Chem. Eng. J. 2021, 415, 128966.
  14. Ma, J.; Cui, Y.; Li, A.; Zhang, W.; Liang, J.; Wang, S.; Zhang, L. Evaluation of the fate of nutrients, antibiotics, and antibiotic resistance genes in sludge treatment wetlands. Sci. Total Environ. 2020, 712, 136370.
  15. Chen, J.; Liu, Y.S.; Su, H.C.; Ying, G.G.; Liu, F.; Liu, S.S.; He, L.Y.; Chen, Z.F.; Yang, Y.Q.; Chen, F.R. Removal of antibiotics and antibiotic resistance genes in rural wastewater by an integrated constructed wetland. Environ. Sci. Pollution Res. 2015, 22, 1794–1803.
  16. Chen, C.; Xia, K. Fate of land applied emerging organic contaminants in waste materials. Curr. Pollut. Rep. 2017, 3, 38–54.
  17. Duan, M.; Li, H.; Gu, J.; Tuo, X.; Sun, W.; Qian, X.; Wang, X. Effects of biochar on reducing the abundance of oxytetracycline, antibiotic resistance genes, and human pathogenic bacteria in soil and lettuce. Environ. Pollut. 2017, 224, 787–795.
  18. Zhu, B.; Chen, Q.; Chen, S.; Zhu, Y.G. Does organically produced lettuce harbor higher abundance of antibiotic resistance genes than conventionally produced? Environ. Int. 2017, 98, 152–159.
  19. Zhi, S.; Ding, G.; Li, A.; Guo, H.; Shang, Z.; Ding, Y.; Zhang, K. Fate of antibiotic resistance genes during high solid anaerobic digestion with pig manure: Focused on different starting modes. Bioresour. Technol. 2021, 328, 124849.
  20. Berendonk, T.U.; Manaia, C.M.; Merlin, C.; Fatta-Kassinos, D.; Cytryn, E.; Walsh, F.; Bürgmann, H.; Sørum, H.; Norström, M.; Pons, M.N.; et al. Tackling antibiotic resistance: The environmental framework. Nat. Rev. Microbiol. 2015, 13, 310–317.
  21. Wang, P.; Yuan, Q.; Zhou, W. Study on photocatalytic degradation and reaction kinetics of tetracycline antibiotics in biogas slurry. Trans. Chin. Soc. Agric. Eng. 2018, 34, 193–198.
  22. Berg, J.; Thorsen, M.K.; Holm, P.E.; Jensen, J.; Nybroe, O.; Brandt, K.K. Cu exposure under field conditions coselects for antibiotic resistance as determined by a novel cultivation-independent bacterial community tolerance assay. Environ. Sci. Technol. 2010, 44, 8724–8728.
  23. Yang, Q.; Ren, S.; Niu, T.; Guo, Y.; Qi, S.; Han, X.; Liu, D.; Pan, F. Distribution of antibiotic-resistant bacteria in chicken manure and manure-fertilized vegetables. Environ. Sci. Pollut. Res. 2014, 21, 1231–1241.
  24. Ye, M.; Sun, M.; Feng, Y.; Wan, J.; Xie, S.; Tian, D.; Zhao, Y.; Wu, J.; Hu, F.; Li, H.; et al. Effect of biochar amendment on the control of soil sulfonamides, antibiotic-resistant bacteria, and gene enrichment in lettuce tissues. J. Hazard. Mater. 2016, 309, 219–227.
  25. Guo, X.P.; Li, J.; Yang, F.; Yang, J.; Yin, D. Prevalence of sulfonamide and tetracycline resistance genes in drinking water treatment plants in the Yangtze River Delta, China. Sci. Total Environ. 2014, 493, 626–631.
  26. Yang, Y.; Li, B.; Zou, S.H.; Fang, H.H.; Zhang, T. Fate of antibiotic resistance genes in sewage treatment plant revealed by metagenomic approach. Water Res. 2014, 62, 97–106.
  27. Bulgarelli, D.; Rott, M.; Schlaeppi, K.; Ver Loren van Themaat, E.; Ahmadinejad, N.; Assenza, F.; Philipp Rauf, P.; Huettel, B.; Reinhardt, R.; Elmon Schmelzer, E.; et al. Revealing structure and assembly cues for Arabidopsis root-inhabiting bacterial microbiota. Nature 2012, 488, 91–95.
  28. He, S.; Wang, Y.M.; Li, C.S.; Li, Y.; Zhou, J. The nitrogen removal performance and microbial communities in a two-stage deep sequencing constructed wetland for advanced treatment of secondary effluent. Bioresour. Technol. 2018, 248, 82–88.
  29. He, T.; Wei, G.; Luan, Z.Y.; Xie, S.G. Spatiotemporal variation of bacterial and archaeal communities in a pilot-scale constructed wetland for surface water treatment. Appl. Microbiol. Biotechnol. 2015, 100, 1479–1488.
  30. Chen, Q.L.; An, X.L.; Zhu, Y.G.; Xie, S. Application of struvite alters the antibiotic resistome in soil, rhizosphere, and phyllosphere. Environ. Sci. Technol. 2017, 51, 8149–8157.
  31. Duran, P.; Thiergart, T.; Garrido-Oter, R.; Agler, M.; Kemen, E.; Schulze-Lefert, P.; Hacquard, S. Microbial interkingdom interactions in roots promote Arabidopsis survival. Cell 2018, 175, 973–983.
  32. Zhang, Y.J.; Hu, H.W.; Chen, Q.L.; Singh, B.K.; Yan, H.; Chen, D.; He, J.Z. Transfer of antibiotic resistance from manure-amended soils to vegetable microbiomes. Environ. Int. 2019, 130, 104912.
  33. Frank, A.; Saldierna, G.J.; Shay, J. Transmission of bacterial endophyte. Microorganisms 2017, 5, 70.
  34. Vandenkoornhuyse, P.; Quaiser, A.; Duhamel, M.; Le Van, A.; Dufresne, A. The importance of the microbiome of the plant holobiont. New Phytol. 2015, 206, 1196–1206.
Contributors MDPI registered users' name will be linked to their SciProfiles pages. To register with us, please refer to : , , , ,
View Times: 341
Revisions: 5 times (View History)
Update Date: 21 Mar 2023
Video Production Service