NEWS - Anyone with an open wound is constantly exposed to dangerous infections, so antibiotics have become a keystone of modern medicine. However, the world continues to face a global antibiotic crisis, as more and more bacterial strains become resistant, while the discovery of new antibiotics is much slower.
A large number of antibacterial agents are derived from bacterial metabolites. Enteropathogenic Escherichia coli (EPEC) is a pathogen that causes intestinal infections characterized by thinning of the microvilli and lesions of the intestinal epithelium associated with abnormal actin polymerization.
Almost 70% of all antibiotics currently come from actinobacteria in the soil and most of the unexplored environments on Earth. Recently, the search for actinobacteria in other habitats, especially in the ocean, such as compounds isolated from marine species, is a promising strategy.
"Here we show how advanced screening assays can identify antivirulence and antibacterial metabolites from actinobacterial extracts. Compounds that inhibit the virulence of EPEC without affecting its growth and compounds that inhibit the growth of actinobacteria," says Päivi Tammela from the University of Helsinki.
Tammela and team developed a series of novel methods to simultaneously test the antivirulence and antibacterial effects of hundreds of unknown compounds. EPEC attaches to cells in the intestine, then injects virulence factors into the host cell to hijack the molecular machinery, causing severe diarrhea, especially in children, and often fatal.
The researchers identified potential antivirulence compounds for EPEC infection among bacterial metabolites harvested from actinobacteria from the Arctic Ocean by applying a virulence-based screening assay. They demonstrated the suitability of this antivirulence assay to screen fractions of actinobacterial extracts for bioassay-guided metabolite identification.
The tested compounds came from four actinobacterial species isolated from invertebrates collected off the coast of Svalbard during an expedition on the Norwegian research vessel "Kronprins Haakon" in August 2020. These bacteria were then cultured, cells were extracted, and their contents were separated into fractions. Each fraction was tested in vitro against EPEC attached to colorectal cancer cells.
The researchers found two unknown compounds with strong antivirulence or antibacterial activity. One from an unknown strain (T091-5) in Rhodococcus and the other from an unknown strain (T160-2) from Kocuria.
The compounds showed two complementary types of activity. First, they inhibited the formation of the “actin pedestal” by EPEC bacteria, a key step by which the pathogen attaches to the intestinal lining. Second, they inhibited the binding of EPEC to the Tir receptor on the surface of host cells, a step required to rewire intracellular processes and cause disease.
The researchers used sophisticated analytical techniques to determine the most promising active compound from T091-5, which is likely to be a phospholipid, a class of fatty phosphorus-containing molecules that play a key role in cellular metabolism.
“The next step is to optimize the culture for compound production and isolate sufficient quantities of the compounds to elucidate their individual structures and further investigate their bioactivity,” Tammela said.
Original research
Tuomas Pylkkö, Yannik Karl-Heinz Schneider, Teppo Rämä, Jeanette Hammer Andersen, Päivi Tammela. Bioprospecting of inhibitors of EPEC virulence from metabolites of marine actinobacteria from the Arctic Sea. Frontiers in Microbiology, Volume 15 - 2024. DOI:10.3389/fmicb.2024.1432475
A large number of antibacterial agents are derived from bacterial metabolites. Enteropathogenic Escherichia coli (EPEC) is a pathogen that causes intestinal infections characterized by thinning of the microvilli and lesions of the intestinal epithelium associated with abnormal actin polymerization.
Almost 70% of all antibiotics currently come from actinobacteria in the soil and most of the unexplored environments on Earth. Recently, the search for actinobacteria in other habitats, especially in the ocean, such as compounds isolated from marine species, is a promising strategy.
"Here we show how advanced screening assays can identify antivirulence and antibacterial metabolites from actinobacterial extracts. Compounds that inhibit the virulence of EPEC without affecting its growth and compounds that inhibit the growth of actinobacteria," says Päivi Tammela from the University of Helsinki.
Tammela and team developed a series of novel methods to simultaneously test the antivirulence and antibacterial effects of hundreds of unknown compounds. EPEC attaches to cells in the intestine, then injects virulence factors into the host cell to hijack the molecular machinery, causing severe diarrhea, especially in children, and often fatal.
The researchers identified potential antivirulence compounds for EPEC infection among bacterial metabolites harvested from actinobacteria from the Arctic Ocean by applying a virulence-based screening assay. They demonstrated the suitability of this antivirulence assay to screen fractions of actinobacterial extracts for bioassay-guided metabolite identification.
The tested compounds came from four actinobacterial species isolated from invertebrates collected off the coast of Svalbard during an expedition on the Norwegian research vessel "Kronprins Haakon" in August 2020. These bacteria were then cultured, cells were extracted, and their contents were separated into fractions. Each fraction was tested in vitro against EPEC attached to colorectal cancer cells.
The researchers found two unknown compounds with strong antivirulence or antibacterial activity. One from an unknown strain (T091-5) in Rhodococcus and the other from an unknown strain (T160-2) from Kocuria.
The compounds showed two complementary types of activity. First, they inhibited the formation of the “actin pedestal” by EPEC bacteria, a key step by which the pathogen attaches to the intestinal lining. Second, they inhibited the binding of EPEC to the Tir receptor on the surface of host cells, a step required to rewire intracellular processes and cause disease.
The researchers used sophisticated analytical techniques to determine the most promising active compound from T091-5, which is likely to be a phospholipid, a class of fatty phosphorus-containing molecules that play a key role in cellular metabolism.
“The next step is to optimize the culture for compound production and isolate sufficient quantities of the compounds to elucidate their individual structures and further investigate their bioactivity,” Tammela said.
Original research
Tuomas Pylkkö, Yannik Karl-Heinz Schneider, Teppo Rämä, Jeanette Hammer Andersen, Päivi Tammela. Bioprospecting of inhibitors of EPEC virulence from metabolites of marine actinobacteria from the Arctic Sea. Frontiers in Microbiology, Volume 15 - 2024. DOI:10.3389/fmicb.2024.1432475