New Delhi, Dec 20, 2024, IANS

New Delhi, Dec 20 (IANS) Scientists from the Institute of Nano Science and Technology (INST) Mohali, an autonomous institution of the Department of Science and Technology (DST), have found that nanoplastics derived from single-use plastic bottles (SUPBs) may be contributing to the spread of antibiotic resistance. Amid growing concerns about the joint threats of plastic pollution and antibiotic resistance, the new study, published in the journal Nanoscale, underscores an unrecognised public health risk. Nanoplastics and microorganisms coexist in diverse environments, including the human gut, and research has shown them to affect health. In the study, the INST team traced how plastic nanoparticles could impact bacteria. They focussed on Lactobacillus acidophilus -- which plays a central role in the gut microbiota. Dr. Manish Singh and his team investigated whether nanoplastics could transform beneficial bacteria into carriers of antibiotic-resistance genes and pose a risk to human gut microbiome health. They utilised 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 via a process called horizontal gene transfer (HGT). This particularly occurs through outer membrane vesicle (OMV) secretion in bacteria. They explained that there are two novel mechanisms through which PBNPs facilitate antibiotic resistance gene transfer. One of them is through the direct transformation pathway in which PBNPs act as physical carriers, transporting antibiotic resistance 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 antibiotic resistance genes, become potent vectors for gene transfer across bacterial species, thus facilitating the spread of antibiotic resistance genes even among unrelated bacteria. This reveals an important and previously overlooked dimension of nanoplastics' effects on microbial communities. The study highlights how nanoplastics might unexpectedly contribute to the antibiotic resistance crisis by introducing antibiotic resistance 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 antibiotic resistance genes, potentially transferring these genes to pathogenic bacteria during infections. Protecting beneficial gut bacteria is crucial for immune support, digestion, and disease prevention. Limiting nanoplastic contamination could help preserve gut microbiota integrity, minimising the chances of antibiotic resistance gene transfer from beneficial to pathogenic bacteria and supporting microbiome resilience.