Eve is here. The film aims to send a hopeful message about the possibility of a turnaround in Antarctica’s plastic pollution, which has risen to levels that threaten local marine life. However, it caused the formation of bacterial colonies. These bacteria have the potential to lead to the development of processes that can break down plastics into less hazardous materials at an affordable cost.
But just how many plastic garbage bags ended up in Antarctica is disheartening, if not surprising.
Written by Pere Monras y Riera, pre-doctoral researcher in biodiversity conservation and management, University of Barcelona. Elisenda Balleste, associate professor of microbiology at the University of Barcelona. Originally published on The Conversation
Antarctica, the world’s most remote, harsh and unspoiled continent, is not free from marine pollution. Wherever human activity takes place, plastic debris inevitably follows.
What would the early explorers of this icy wasteland think today when they discovered a continent transformed by permanent fishing operations, research bases, military presence, tourism, and all the effects they have on the environment? Plastic pollution stands out among these, as it creates a unique new ecological niche in the ocean.
When plastic debris enters water, microorganisms quickly colonize the surface and form biofilms. This plastic-derived community, known as the plastisphere, poses a serious threat to marine ecosystems, particularly in the cold and understudied waters of Antarctica.
Plastisphere: A new threat
As plastic debris drifts through the ocean, it undergoes a typical ecological transition, developing a plasticosphere and eventually becoming a complex and specialized microbial community. Plastic not only harbors these microorganisms, but also spreads potentially harmful pathogens such as Vibrio, E. coli, and bacteria with antibiotic resistance genes throughout the marine environment, even in remote and unexplored areas. It also functions as a medium to reach
Plastispheres are not only home to microorganisms, but they can also disrupt the natural balance of marine life on a microscopic level. These changes don’t stay in the ocean, they spread outward and could affect the way the ocean absorbs carbon and produces greenhouse gases. This affects the air we breathe around the world.
But it’s not all bad news. Bacteria such as Alcanivorax sp., Aestuariicella sp., and Marinobacter sp. are known for their potential to degrade plastics and hydrocarbons. and Alteromonas sp. – commonly found on plastic.
Antarctic plastisphere under a microscope: bacteria colonizing polystyrene. author’s own
hostile research environment
Currently, little is known about the plasticosphere, particularly in the Antarctic, and uncovering its dynamics is key to understanding its impact on one of the most remote and fragile marine environments on Earth. Therefore, in our recent study, we aimed to investigate the richness and diversity of microbial communities in the Antarctic ocean plastisphere, especially after initial colonization of plastic debris.
Working in Antarctica is not easy. Just getting to this continent is a huge challenge, and once there, scientists have to deal with a harsh environment: sub-zero temperatures, strong winds, icebergs, and the constant pressure of limited time to complete their research. You have to fight against the conditions. These challenges make every moment in the field both demanding and precious.
This is why we approached our research using controlled and manageable experiments. We set up an aquarium filled with seawater sampled near a Spanish research station on Livingstone Island in the South Shetland Islands. Inside were small, round pellets of three of the most common types of plastic that pollute our oceans: polyethylene, polypropylene, and polystyrene. They were left in ambient conditions (approximately 0 °C and 13–18 h of sunlight) for 5 weeks with the aim of reproducing the most plausible results in the field.
We compared colonization of plastic to an inert surface, glass. Plastic and glass samples were collected periodically to track bacterial colonization.
Plastosphere dynamics in Antarctica
Because studying bacteria means making the invisible visible, we combined several techniques to get a better picture of the plastisphere. Biofilm images were obtained using scanning electron microscopy. We used a combination of flow cytometry and bacterial culture to count total cells and colonies, and sequenced the 16S rRNA gene to identify a set of bacterial settlers.
This careful approach revealed that time is the primary driver of change. Microorganisms quickly colonized the plastic, and within two days, bacteria such as the genus Colwellia were already fixed on the surface, and from the first settlers, including other genera such as Sulfitobacter, Graciecolla, and Lewinella. It showed a clear progression to a mature and diverse biofilm.
Although these species are also detected in water, they show a clear preference for the social life of biofilm communities. Furthermore, no clear differences between the bacterial communities of plastic and glass were detected. This suggests that any stable surface may harbor these bacterial groups.
Similar processes occur in other oceans, but the process appears to be slower in Antarctica. The cooler temperatures in this region slow the development of bacteria.
Bacteria that eat plastic?
One of the key findings was the presence of Oleispira sp. About polypropylene. This bacterium is a hydrocarbon-degrading bacterium, meaning it belongs to a group of microorganisms that can break down oil and other pollutants.
Their role within Antarctic plastiospheres raises important questions, including whether this type of bacteria can reduce the effects of plastic pollution. If so, they could hold the key to the future of Antarctica and our oceans.
However, much remains to be discovered, especially regarding the potential of bioremediation in extreme environments. Understanding these processes could pave the way for innovative strategies to address the growing challenge of plastic waste in marine ecosystems.
