Simultaneous Dissemination of Nanoplastics and Antibiotic Resistance by Nematode Couriers

Thisstudy reports the dissemination of antibiotic-resistantbacteria and associated antibiotic-adsorbed nanoplastics across thesoil by bacterivorous nematodes. Nanoplastics (NPs) are increasingly recognized as a newlyemergingpollutant in the environment. NPs can enable the colonization of microbialpathogens on their surfaces and adsorb toxic pollutants, such as heavymetals and residual antibiotics. Although the dissemination of plasticparticles in water bodies and the atmosphere is widely studied, thedissemination of NPs and adsorbed pollutants on land, via biologicalmeans, is poorly understood. Since soil animals, such as the bacterivorousnematode Caenorhabditis elegans (C. elegans), are highly mobile, this raises the possibilitythat they play an active role in disseminating NPs and adsorbed pollutants.Here, we established that antibiotic-resistant bacteria could aggregatewith antibiotic-adsorbed NPs to form antibiotic-adsorbed NP-antibioticresistant bacteria (ANP-ARB) aggregates, using polymyxins (colistin)as a proof-of-concept. Colistin-resistant mcr-1 bearing Escherichia coli from a mixed population of resistantand sensitive bacteria selectively aggregate with colistin-ANPs. Inthe soil microcosm, C. elegans fedon ANP-ARB clusters, resulting in the rapid spread of ANP-ARB by thenematodes across the soil at a rate of 40-60 cm per day. Ourwork revealed insights into how NPs could still disseminate acrossthe soil faster than previously thought by "hitching a ride"in soil animals and acting as agents of antibiotic-resistant pathogensand antibiotic contaminants. This poses direct risks to ecology, agriculturalsustainability, and human health.