Credit:- Sugandh Khandelwal
Recent studies have highlighted the role of nanoplastics—minute plastic particles less than 1 micrometer in size—in facilitating the spread of antibiotic resistance genes (ARGs) among bacteria. These particles can originate from the breakdown of larger plastic items, such as bottles, packaging, and synthetic textiles, or be intentionally manufactured for use in products like cosmetics, cleaning agents, and pharmaceuticals. Due to their small size, nanoplastics are highly mobile and persistent in the environment, which poses unique challenges to both ecosystems and human health. This phenomenon poses a significant public health concern, as it can transform beneficial bacteria into carriers of ARGs, potentially diminishing the effectiveness of antibiotics.
Joint threats of plastic pollution and antibiotic resistance
Arecent study by Indian scientists showed Nanoplastics derived from single-use plastic bottles (SUPBs) contribute to the spread of antibiotic resistance (AR), underscoring an unrecognized public health risk.According to a press release by the Ministry of Science & Technology, scientists at the Institute of Nano Science and Technology (INST) Mohali, an autonomous institution of the Department of Science and Technology (DST),tried to trace how plastic nanoparticles could impact bacteria.
The scientists were led to the study by the joint threats of plastic pollution and antibiotic resistance. Recognizing the central role of Lactobacillus acidophilus in the gut microbiota, Dr. Manish Singh and his team investigated whether nanoplastics could transform beneficial bacteria into carriers of AR genes and pose a risk to human gut microbiome health.They utilized the used plastic water bottles to synthesise environmentally relevant nanoplastics particles as these polyethylene terephthalate bottle-derived nanoplastics (PBNPs) better represent the actual pollutant nanoplastics generated due to dumping of single use plastic bottles and containers.
The scientists demonstrated that PBNPs can facilitate the cross-species gene transfer from E. coli to Lactobacillus acidophilus, a significant bacteria found in human gut microbiota, through a process called horizontal gene transfer (HGT), particularly through outer membrane vesicle (OMV) secretion in bacteria. According to the researchers there are two novel mechanisms through which PBNPs facilitate AR gene transfer. One of them is through direct transformation pathway in which PBNPs act as physical carriers, transporting AR plasmids across bacterial membranes and promoting direct gene transfer between bacteria. The other one is through OMV-Induced Transfer Pathway in which PBNPs induce oxidative stress and damage to bacterial surfaces, which makes stress response genes pro-active and triggers an increase in outer membrane vesicle (OMV) secretion. These OMVs, loaded with AR genes, become potent vectors for gene transfer across bacterial species, thus facilitating the spread of AR genes even among unrelated bacteria. This reveals an important and previously overlooked dimension of nanoplastics’ effects on microbial communities.
The study published in the journal ‘Nanoscale’ highlights how nanoplastics might unexpectedly contribute to the AR crisis by introducing AR genes to beneficial gut bacteria like Lactobacillus acidophilus, which may subsequently pass these genes to pathogens. It indicates that beneficial bacteria like Lactobacillus acidophilus could act as reservoirs for AR genes, potentially transferring these genes to pathogenic bacteria during the course of infections.
Protecting beneficial gut bacteria is crucial for immune support, digestion, and disease prevention. Limiting nanoplastic contamination could help preserve gut microbiota integrity, minimizing the chances of AR gene transfer from beneficial to pathogenic bacteria and supporting microbiome resilience. With increasing plastic pollution, this finding highlights the need for strict safety guidelines, awareness programs as well as the necessity of policies that prioritize responsible usage of plastics and it’s adequate waste management to safeguard the human health and microbiome stability.
How do biofilms on nanoplastic surfaces enhance horizontal gene transfer?
The presence of nanoplastics can enhance the exchange of ARGs through several mechanisms. Nanoplastics can serve as surfaces for biofilm development. Biofilms are communities of microorganisms encased in a self-produced matrix that adheres to surfaces. Within biofilms, bacteria are in close proximity, facilitating HGT. The unique structure of biofilms on nanoplastics can increase the overlap between different species, thereby promoting the spread of ARGs through horizontal gene transfer. Studies have shown that as microplastic diversity increases, there is a corresponding rise in the abundance of soil ARGs, virulence factor genes (VFGs), and mobile genetic elements (MGEs). This suggests that diverse microplastic pollution can enhance the spread of ARGs in the environment.
Why do nanoplastics promote the spread of AR genes?
Nanoplastics, especially those derived from single-use plastic bottles made of polyethylene terephthalate (PET), have been identified as emerging agents in the dissemination of antibiotic resistance. These particles can interact with bacteria in various environments, including the human gut, creating conditions conducive to horizontal gene transfer (HGT)—the process by which genetic material is exchanged between organisms without reproduction. This interaction can lead to the transfer of ARGs between different bacterial species. The more diverse the bacterial population, the higher the chance of ARGs spreading across species.
How antibiotic resistance through nanoplastics leads to treatment challenges?
The transfer of ARGs to beneficial bacteria, such as those in the human gut microbiota, can have serious health implications. Beneficial bacteria transformed into ARG carriers can act as reservoirs, potentially transferring resistance genes to pathogenic bacteria. This process can lead to infections that are more difficult to treat due to reduced antibiotic efficacy. Limiting nanoplastic contamination could help preserve gut microbiota integrity, minimizing the chances of ARG transfer. Nanoplastics facilitate horizontal gene transfer (HGT) between different bacterial species, including pathogenic ones. This increases the genetic diversity of resistant bacteria, making it more difficult for antibiotics to target and eliminate these infections effectively. As the spread of antibiotic-resistant bacteria accelerates due to nanoplastics, existing antibiotics may become less effective, leading to the need for stronger, more expensive treatments. This can increase the risk of treatment failure, longer hospital stays, and greater healthcare costs.
What steps can be taken to mitigate the negative impact?
The interaction between nanoplastics and bacteria represents a significant pathway for the spread of antibiotic resistance. Understanding the mechanisms by which nanoplastics facilitate ARG transfer is crucial for developing strategies to mitigate this emerging public health risk. Limiting the use of single-use plastics and encouraging alternatives like biodegradable materials can decrease plastic pollution. Implementing stricter regulations on plastic waste management and recycling can reduce the accumulation of microplastics and nanoplastics in the environment. Also upgrading wastewater treatment plants to capture nanoplastics and microplastics can prevent them from entering natural water systems where they may affect bacterial populations as well as using filtration methods such as advanced membrane technology can help remove smaller plastic particles. Raising awareness about the dangers of plastic pollution and its connection to antibiotic resistance can encourage more responsible consumer behavior and support for policy changes.
Studies on Nanoplastics and Antibiotic Resistance spread:
Nanoplastics Promote the Dissemination of Antibiotic Resistance Genes in Soil Microbial Communities
The study found that both microplastics and nanoplastics facilitate the transfer of ARGs among soil bacteria, with nanoplastics having a more substantial impact. The research highlights the size-dependent effects of plastic particles on microbial communities and underscores the need for regulating plastic waste to mitigate ARG dissemination.
Charged Nanoplastics Differentially Affect the Conjugative Transfer of Plasmid-Borne Antibiotic Resistance Genes
The research investigates how the surface charge and colloidal stability of nanoplastics influence the conjugative transfer of plasmid-borne ARGs. The study uses polystyrene nanoplastics as a representative to understand the mechanisms underlying ARG spread facilitated by nanoplastics
How Microplastics and Nanoplastics Shape Antibiotic Resistance
The article reviews studies measuring indicator genes of horizontal gene transfer on microplastics, providing evidence that microplastics can affect the spread of antibiotic resistance. The review also discusses the potential impacts of microplastics and nanoplastics on the occurrence and dissemination of ARGs in environmental microorganisms.
Antibiotic Activity Altered by Interaction with Nanoplastics
The study reveals that nanoplastics can reduce antibiotic effectiveness and promote resistance by forming stable aggregates with drugs. The research highlights the complex interactions between nanoplastics and antibiotics, which can lead to altered antibiotic activity and increased resistance.
Source of information:
https://pib.gov.in/PressReleaseIframePage.aspx?PRID=2086071
https://pubs.rsc.org/en/content/articlelanding/2023/en/d3en00229b?utm_source
https://pmc.ncbi.nlm.nih.gov/articles/PMC10767152/?utm_source
