Unveiling How Animals Control Friendly Bacteria for Defense

Thousands of types of bacteria live in the human gut. They help digest the food we eat and absorb nutrients, but these bacteria don’t just do this to be kind to humans, there is a benefit for them too.

Elizabeth Heath-Heckman, an assistant professor in the College of Natural Science, has received a five-year National Institutes of Health grant from the National Institute for General Medical Sciences totaling $1.9 million to support her research studying the bacteria animals like squid and newts use to protect themselves. This research could provide insights into how humans maintain beneficial bacteria in their gut.

Specifically, this NIH Maximizing Investigators’ Research Award, or MIRA grant, will focus on how animals make sure that the bacteria that live with them are cooperating in a mutually beneficial way.

Heath-Heckman and her team study the beneficial relationship between the Hawaiian bobtail squid and the luminous bacteria contained in its light organ that glows to camouflage the squid from predators.

I’m really interested in learning how the squid ensures the bacteria keeps making light. This is costly for the bacteria but likely essential for the squid to protect itself.”

Elizabeth Heath-Heckman, Assistant Professor, College of Natural Science, Michigan State University

Studying ways bacteria can help animals defend themselves against predators led Heath-Heckman to collaborate with Heather Eisthen, a professor in the College of Natural Science, and her lab’s research with rough-skinned newts. Bacteria on the newt’s skin produce tetrodotoxin, or TTX, which is extremely toxic to animals that eat the newts.

“Both the squid and the newt have defensive symbiotic relationships where they use their bacteria to avoid being eaten,” said Heath-Heckman. “But in either case, they’re both animals and they both are interacting with bacteria that are as different from them as our bacteria are different from us.”

Heath-Heckman has been exploring the way squid “talk” to their bacteria and applying that model to human gut health.

“We can apply these basic principles that underpin how bacteria, and their hosts, are associating with each other and use that to find commonalities in terms of strategy or ecological or evolutionary principles across those systems,” said Heath-Heckman. “This project is very much at the nexus of health, evolution, developmental biology and immunology.”