Could the deep Arctic Sea give us antibiotics?

A study has found promising antibiotic candidates inside bacteria harvested from the deep Arctic Sea.

The research, by Finnish and Norwegian researchers, is published in Frontiers in Microbiology.

Antibiotic discovery has slowed in recent decades, which has exacerbated the risks of antibiotic resistance.

Most licensed antibiotics – about 70% – have been derived from a type of soil-dwelling bacteria called actinobacteria.

“For example, members of the Streptomyces genus produce several secondary metabolites, including clinically useful antibiotics such as tetracyclines, aminoglycocides and macrolides,” says corresponding author Dr Päivi Tammela, a professor at the University of Helsinki, Finland.

But soil isn’t the only place these bacteria can be found.

“Marine actinobacteria found in the sea, on the seafloor, or within the microbiome of marine organisms, have received far less attention as possible sources of antibiotics,” says Tammela.

The Norwegian cohort of researchers in the study, based at the Arctic University of Norway, sampled invertebrates and collected the bacteria from marine life while on a research cruise of the Arctic Ocean in 2020.

“They try to access different unique locations in the Arctic, but the goal is as high biodiversity as possible,” says Tammela.

“They collect what they get up at the deck carefully as we know that sometimes the same species that are collected but at different locations can give origin to different bacteria and chemistry.”

In the lab, the team cultured the bacteria and separated their cells into fractions.

Then, they used a collection of techniques to test unknown compounds in the samples simultaneously for antibacterial activity.

The researchers tested their samples against a specific strain of enteropathogenic E. coli which causes severe diarrhoea in young children.

They found two compounds with powerful antibacterial activity.

Both substances could stop the E. coli from attacking host cells, by inhibiting the activity of certain proteins in the bacterial cells.

One of the compounds did this without inhibiting the growth of the E. coli. This is particularly important because it could work as an antibiotic without encouraging the bacteria to evolve resistance.

While the researchers didn’t culture enough of either compound to identify their molecular structures, they believe the more promising one is a type of compound called a phospholipid.

“Findings described in the paper are very early, and plenty of further research will be required to assess their true potential for becoming clinically useful,” Tammela tells Cosmos.

“At this point, it is impossible to speculate if the compounds will ever be useful as treatments.”