Komodo Dragons Get By With a Little Help from E. Coli

            Komodo dragons (Varanus komodoensis) are the largest lizards in the world.  They are one of the monitor lizard species and are located in only five islands in Indonesia. They can grow to the size of three meters and are known to be vicious predators. They are dangerous and tear their prey up with their sharp teeth. They have been known to kill buffalos, deer, pigs and even humans! But besides having very sharp and strong teeth, something else is helping them kill their prey, the septic bacteria in their mouths.

            The septic bacteria do not originate in the dragons. They are transmitted to them at a young age from devouring flesh of giant mammals and other foods sources. They can also be transmitted when the Komodo dragons fight and bite each other. I believe this relationship between the dragons and bacteria is some type of mutualism because both the bacteria and dragon benefit from this. The bacteria have a place to stay and can grow, get food and spread to other organisms, and the Komodo dragon have a bacterium that can poison its prey and make meal hunting a lot more efficient.

            Scientists have confirmed that feeding on mammals, especially buffalo, has given the dragons their micro-sized friends. In fact, a single buffalo can “infect” twelve dragons with the bacteria. These bacteria are not just one type, but are Escherichia coli, Staphylococcus aureus, and Klebsiella typhimurium. The E. coli made up of 68% of the bacterium population in the Komodo’s mouth. Scientists also have confirmed that the physiology of the giant lizards have protected them from the bacteria, rather than harm them, like to the mammals. However, immunity from these bacteria is not a passed down trait. Young Komodo dragons must gain immunity from prey or from fellow dragons. Even then, the bacteria are not highly effective. Preys have been known to escape while the “venom” from the bacteria is fully effective hours later. But nonetheless, there is an evolutionary relationship between the bacteria and the Komodo dragons. And it does look like it will change as long as both sides are benefiting from the hunt.

Sources:

Bull JJ, Jessop TS, Whiteley M (2010) Deathly Drool: Evolutionary and Ecological Basis of Septic Bacteria in Komodo Dragon Mouths. PLoS ONE 5(6): e11097. https://doi.org/10.1371/journal.pone.0011097

Merchant, Mark, Danyell Henry, Rodolfo Falconi, Bekky Muscher, & Judith Bryja. "Antibacterial activities of serum from the Komodo Dragon (Varanus komodoensis)." Microbiology Research[Online], 4.1 (2013): e4. Web. 25 Apr. 2017

(Pictures are also from sources)