They study with nanotechnology the bacteria of Antarctic species and the effects of climate change

Punta Arenas, December 19, 2022.- For more than five years, researchers from the Chilean Antarctic Institute (INACH) have been dedicated to studying the bacteria that live in association with Antarctic marine organisms such as sponges and mollusks, as well as fish such as marbled cod and Antarctic cod. They have done so by applying state-of-the-art sequencing technologies. Now with the incorporation of a team called MinION, the INACH completed its platform for genomic applications.

The set of microorganisms (bacteria, viruses, fungi) and their genes is known as microbiome. These microorganisms exist in a dynamic balance with various living beings in areas as special as the skin, intestines or mouth. These interactions symbiotic –understood as the way in which individuals relate to obtain benefit from at least one of the two– help them survive and fulfill roles that benefit the ecosystem.

However, the modification of these communities by different metabolic or environmental factors results in a process called dysbiosis, which consists of the imbalance of a normal microbiota. Changes are currently occurring globally and under which it could be predicted that environmental stressors (such as increased temperatures and marine acidification) could affect symbiotic interactions with possible effects on both host and non-host species. associated communities.

What has been studied so far?

During the pandemic, the INACH team published a Article on the effects of ocean warming and seafloor impact by icebergs on shaping the sponge microbiome Isodictya kerguelenensis on the Antarctic peninsula.

Previously, this same team had published another Article on the stability of the microbiome in time and space. They focused on the bacterial communities of four species of Antarctic sponges that were tagged and monitored during three austral summers, for a total of 24 months. Here they found a high stability of the bacterial communities during the two years of monitoring despite having registered significant temperature rises. This demonstrated that the sponges maintained their microbiome despite the variability of the environment.

In another article, the stability of the microbiota in two sponge species of the same genus in Magallanes and also in Antarctica was compared and revealed a very similar composition, despite the distance. Other more recent studies confirm the high stability of the microbiome, even in places with a greater influence of glaciers or variability in water temperature.

Recent work carried out by the INACH team and by other international researchers provides new information on the microbial communities associated with various species of sponges in parts of the Peninsula and in Terra Nova Bay in the Ross Sea region.

In short, sponges are considered an exceptional reservoir of microbial diversity and these investigations have provided greater insight into the role of symbionts in climate change scenarios.

“When we began to study the effect of warming on sponges in 2015, there was very little knowledge and we thought that sponges would be big losers from this phenomenon. However, the species that we have been able to study have shown the opposite: the relationship with bacteria seems to be more stable than we thought, so these species would not be directly affected by temperature rises”, says Dr. César Cárdenas, INACH researcher.

Not only space is studied, it is also key to understand the change of the microbiome in the different life stages of organisms. This is how researchers have observed the microbiomes of sea urchin larvae and adult specimens. There it has been determined that the selection of bacterial communities occurs in the larval stage; however, the role of these selected bacteria for larvae or adults of the same species remains unresolved.

Much remains to be understood about the organization and functionality of marine invertebrates and fish as hosts for these bacteria. Similarly, estimates of the fitness of host-symbiont associations under multiple stressors are still scarce.

In addition to studying marine invertebrates and their associated bacterial communities, the scientists contributed to the knowledge of the diversity of new viruses in penguins on Magdalena Island in the Magallanes and Chilean Antarctic region.

The head of the INACH Scientific Department, Dr. Marcelo González, explained that they are currently studying Antarctic fish, mainly those living species that they keep in their laboratories. “We are working to reconstruct the microbiome of Antarctic fish, comparing the changes that they undergo in their acclimatization stage in the aquariums that will be part of the future International Antarctic Center, as well as characterizing the biological filter of the aquarium that contains these polar species. For this we are working together with colleagues from the Korean Polar Institute (KOPRI)”, he explains.

And how can they study such tiny organisms?

Scientists use DNA sequencing technologies like Illumina. In this sense, sequencing began in the INACH laboratory using an innovative nanotechnology called MinION, which allows sequencing anywhere, since it is a small device the size of a cell phone.

“Sequencing technology is based on the use of nanopores; DNA is analyzed directly by pushing it through a pore suspended in a membrane. The nucleotides or letters that make up the DNA differ due to the changes in electrical current that occur during its passage through the membrane. The energy necessary for its operation is extracted from a USB port of the computer to which it is connected and it also has its own analysis program”, affirms Alejandro Font, researcher and manager of the INACH laboratory.

In short, this new equipment will facilitate the work of scientists to continue expanding the knowledge of the bacterial communities associated with the different species in Antarctica.

The INACH is a technical body of the Ministry of Foreign Affairs with full autonomy in everything related to Antarctic matters of a scientific, technological and dissemination nature. INACH complies with the National Antarctic Policy by encouraging the development of excellent research, effectively participating in the Antarctic Treaty System and related forums, strengthening Magallanes as the gateway to the White Continent and carrying out actions to disseminate Antarctic knowledge among citizens. .