Catfish and all manners of fish have a mucus and slimy outer coating on their bodies making them hard to hold onto. That mucus might be the key to the next antibiotic, say scientists who have worked with the skin of the scaleless, farmed African catfish.
Additional testing is necessary to prove the compound is safe and effective for use as future antibiotic, but it could be a potent new tool against antimicrobial-resistant bacteria such as extended-spectrum beta-lactamase (ESBL) producing E. coli.
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“The global public health threat due to antimicrobial resistance necessitates the search for safe and effective new antibacterial compounds,” says Hedmon Okella, a postdoctoral researcher at the University of California, Davis, and led the project.“In this case, fish-derived antimicrobial peptides present a promising source of potential leads.”
For the study, the researchers extracted several peptides (short chains of amino acids) from African catfish skin mucus and used machine learning algorithms to screen them for potential antibacterial activity.
They then chemically synthesized the most promising peptide, called NACAP-II, and tested its efficacy and safety on ESBL-E. coli and mammalian blood cells, respectively.
These tests showed that NACAP-II caused the bacteria to break open, or lyse, without appearing to harm the mammalian blood cells. “Preliminary findings indicate that this promising peptide candidate potentially disrupts the bacterial cell envelope to cause lysis at a very low concentration,” Okella said.
The place where the peptide was found — in the mucus on the skin of farmed African catfish — is not as unlikely as it may seem. As anyone who has tried to hold one can attest, fish are enveloped in a slippery layer of mucus. This mucus is known to protect the fish against infections by physically carrying germs off of the skin and by producing antimicrobial compounds such as the one Okella’s team isolated.
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Many existing medicines are based on compounds that were first found in nature, and scientists speculate that marine and aquatic organisms represent a particularly rich — though largely untapped — source of bioactive compounds. Ever pick up a snail and try to wash off the slime it leaves behind?
As a next step, the researchers plan to study the peptide’s effects in animal models and explore strategies to produce it inexpensively. “We are currently utilizing chemical synthesis to upscale the production of this peptide that we believe will one day be of use as drug candidate in the battle against antimicrobial resistance,” Okella said.
