Sloths are known for their thick fur which is home to a wide range of microorganisms and insects. A recent study shows that some species of fungi found in sloth fur could eventually be a potent force against certain parasites, cancers, and bacteria. The paper was submitted by lead author Sarah Higginbotham of the Smithsonian Tropical Research Institute and was published in PLOS One.

Sloth fur has two layers. The inner layer is short, fine, and serves to keep the sloth warm. The course outer layer is where many of the organisms live. Green algae grows in the cracks of the hair and lives symbiotically with the sloth. The algae has a nice place to grow and the sloth benefits by getting a green tint in its fur, which helps camouflage it among the leaves in the rainforest. 

For this study, researchers collected 84 species of fungus that reside in the three-toed sloths’ (Bradypus variegatus) course fur. The samples came from nine different sloths who live in Panama’s Soberanía National Park. After identifying the fungi, the team found that 28 operational taxonomic units were represented in this study.

Of the fungi collected, 74 were cultured and subjected to in vitro testing for biological activity against diseases. Three species of fungi were shown to be effective against the human breast cancer strain MCF-7, which the longest-lived breast cancer strain and is very commonly used in biomedical research. 

Eight of the fungi tested had high levels of bioactivity against Trypoanosoma cruzi, the parasite associated with Chagas disease. Chagas can result in swelling, fever, diarrhea, and enlargement of the liver. Plasmodium falciparum, the parasite to blame for malaria, was affected by two of the fungi. Three of the fungi were active against both T. cruzi and MCF-7.

Since the discovery of penicillin in 1928, fungi have been a great source of antibiotics. The researchers tested the fungi against fifteen types of bacteria which were a combination of gram-positive and gram-negative. Twenty types of fungi were shown to be active against at least one strain of bacteria, and gram-negative bacteria was more susceptible to the fungi than gram-positive. The research also discovered a single species of fungus which was active against methicillin-resistant Staphylococcus aureus (MRSA), which is responsible for thousands of deaths each year.

Now, it is very important to note that the fungi was able to exhibit this bioactivity in a petri dish under controlled laboratory conditions. It is relatively easy to kill diseases under these circumstances, as it can also be done with bleach, ammonia, or a blowtorch. Future research will seek to refine these disease-fighting properties so that they may one day be useful for in vivo applications. Please don’t go around licking sloths trying to get to the fungi. The team would also like to explore the five other sloth species in order to determine if they also harbor large quantities of bioactive fungi.