When “remote” does not mean isolated
Antarctica is often seen as a symbol of environmental isolation. However, this perception becomes more nuanced in regions such as the Fildes Peninsula (King George Island), one of the most active scientific hubs in Antarctica. Here, research stations, logistics and human activity coexist with extreme environmental conditions. At the same time, plastic debris (transported over long distances or introduced locally) has been detected in the region. Beyond documenting the presence of plastic debris, we focused on understanding the functional genetic potential associated with these materials: what kind of microbial functions are linked to plastisphere communities in Antarctic environments?
Looking beyond taxonomy: the resistome and mobilome
Plastic debris is rapidly colonised by microorganisms, forming biofilms known as the plastisphere. While these communities have been described in multiple environments, their functional potential in Antarctic inland systems remains poorly understood. In this study, we focused on two key components: i) the resistome (antibiotic resistance genes, ARGs) and ii) the mobilome (mobile genetic elements, MGEs). Using high-throughput molecular approaches, we screened hundreds of ARGs and MGEs and compared plastic-associated assemblages with their surrounding environments. Our aim was to determine whether plastics act as reservoirs of resistance-related genes in this context.
Plastics are enriched in resistance-related genes
Across all samples, we detected a high diversity of ARGs and MGEs, including a large proportion of the genes targeted in the screening platform. Several consistent patterns emerged. A substantial proportion of ARGs and MGEs were found exclusively in plastics. Plastics showed higher diversity and richness of both ARGs and MGEs and plastics exhibited higher relative gene copy numbers. In addition, compositional analyses revealed that the resistome and mobilome associated with plastics were distinct from those of surrounding environments, indicating that plastics are associated with enriched and structured genetic assemblages relative to the surrounding environment.
Comparison with the surrounding environment is key
These patterns were revealed through the systematic comparison of plastisphere samples with their surrounding environments. By analysing plastics alongside soil and water matrices collected at the same sites, we showed that plastics are associated with a consistent enrichment and distinct composition of ARGs and MGEs relative to the surrounding environment. This comparative approach allowed us to distinguish between background environmental resistomes and those associated with plastic debris.
Differences in function are more pronounced than in community composition
One of the most notable results of the study is the contrast between functional and taxonomic patterns. While the resistome and mobilome differed clearly between plastics and surrounding matrices, the bacterial community composition was comparatively stable: most taxa were shared across plastics, soils and water; differences in community structure were relatively subtle; and no consistent major shifts were observed between plastisphere and soil communities. These results indicate that, in these environments, differences associated with plastics appear to be more evident at the functional (genetic) level than at the level of overall community composition.
Signals of gene mobility
Mobile genetic elements play a key role in the spread of antibiotic resistance. In plastisphere samples, we observed a broad diversity of MGEs and more extensive ARG–MGE correlations. These patterns indicate an increased potential for gene mobilization, although the study does not directly measure horizontal gene transfer.
Clinically relevant resistance in remote environments
Among the detected ARGs, we identified: genes classified as high-risk (rank I) and ARGs conferring resistance to synthetic and semi-synthetic antibiotics. Notably, some of these genes were found exclusively in plastisphere samples. At the same time, chemical analyses did not detect antibiotics in soils or waters, suggesting that these patterns are not directly associated with measurable antibiotic contamination in the environment.
Viable resistant bacteria under extreme conditions
To complement the molecular data, antibiotic-resistant bacteria were isolated from plastisphere samples after prolonged freezing. These isolates carried co-existing ARGs and MGEs in their genomes, showing that resistance is not only present at the genetic level but it is also associated with viable microorganisms able to persist after prolonged freezing under Antarctic conditions.
Sampling in a challenging environment
This study was not designed as a large-scale survey. Instead, it focused on plastic debris collected across inland Antarctic sites. Working in Antarctic environments means that sampling is constrained by field conditions. In this case, expanded polystyrene (EPS) and polyurethane (PUR) were the plastic types recovered across the study sites, allowing for consistent comparisons. Combined with high-throughput screening of hundreds of genes, this approach provided a high-resolution view of the resistome and mobilome associated with Antarctic plastispheres.
A broader perspective
Our findings highlight that plastic pollution is not only a physical issue, but also a microbial and genetic one. Even in Antarctic environments, plastics can act as reservoirs of ARGs and MGEs, resistance-related genes are enriched in plastisphere samples and their composition differs from the surrounding environment. At the same time, the study area illustrates that Antarctica should not be seen as uniformly pristine, but as a system where natural conditions and human influence coexist.
Looking ahead
This work opens new questions: Are these resistance genes actively expressed? Do they serve other biological functions besides granting antibiotic resistance? Why do they persist in the absence of antibiotic selection in the environment? How frequently are they mobilised between microorganisms? And how do environmental conditions influence these processes over time? Future studies could expand this work by exploring a broader range of Antarctic environments, including regions with lower levels of human activity, to better understand how these patterns vary across different contexts. In addition, examining a wider diversity of plastic types and increasing spatial coverage would help to further clarify the role of plastispheres in shaping the distribution of resistance-related genes. Addressing these questions will be key to understanding the ecological role of plastispheres in global antibiotic resistance dynamics.
As final a reflection, plastic debris in Antarctic lakes and soils may appear as a simple indicator of pollution. At the microbial level, however, it represents something more complex: the creation of new ecological niches where resistance-related genes can be found enriched, persist, and be associated with mobile genetic elements that enable their potential transfer.
Valenzuela-Lázaro, J. M., Krojmal, E., De Feo, B., Lacerot, G., Lozoya, J. P., Teixeira-de Mello, F., ... & González-Pleiter, M. (2026). Inland Antarctic plastispheres harbour unique and diverse antibiotic resistance genes and mobile genetic elements. Communications Earth & Environment.