Krajmalnik-Brown encourages us to ‘go with our gut’

Krajmalnik-Brown encourages us to ‘go with our gut’

February 7, 2019

February 7, 2019

When Nicole Neuman, the editor of Molecular Cell sought a learned look at the connection of microbes to behavior, they knew exactly who to call: Rosa Krajmalnik-Brown. “Dr. Rosy,” as she’s known at Arizona State University, is becoming increasingly well-known for her interest and expertise in gut-brain interactions.

Molecular Cell is a companion to Cell, the leading journal of biology and the highest-impact journal in the world, so Krajmalnik-Brown knew the invitation to write a “research spotlight piece” would be a good opportunity to help others understand this emerging and interesting science. Krajmalnik-Brown has been researching the microbiome – human and otherwise – for more than a decade. She’s been on a mission to understand how obesity and autism relate to the gut microbiome. Much interest had been focused on her microbiota work with children with autism. This work has recently moved into a placebo-controlled clinical trial that will reveal more about the efficacy of the previously published microbial transfer therapy for children with autism.

An environmental engineer by training, Krajmalnik-Brown does her research at ASU’s Biodesign Institute’s  Swette Center for Environmental Biotechnology as well as the Biodesign Center for Fundamental and Applied Microbiomics. She is a professor in the ASU School of Sustainable Engineering and the Built Environment.

Her opinion piece, A Fruitful Discovery: Can Gut Bacteria Control Hyperactive Behavior?, appears in the February edition of Molecular Cell.  Her mission was to provide a reaction to a recently published study by Schretter, et al., a research team from the California Institute of Technology lead by Dr Sarkis Mazmanian that demonstrated how an enzyme from gut bacteria affected the locomotor behavior of fruit flies. Locomotion is important to physical activities like mating and searching for food.

Krajmalnik-Brown’s piece helps the non-scientist reader understand the basics of gut bacteria:

“Our microbial residents provide important functions that affect our health. The largest population of these residents live in our gut and help us digest food, make vitamins, activate or deactivate our immune system, and interact with our central nervous system. Some researchers have suggested that our microbes control our emotions and perhaps even our eating behavior,” she writes.

Popular interest in the gut-brain connection exploded in 2016 with the publication of Ed Yong’s book, I Contain Multitudes: The Microbes Within Us and a Grander View of Life. Emeran Mayer provided another perspective in his book, The Mind-Gut Connection: How the Hidden Conversation Within Our Bodies Impacts Our Mood, Our Choices, and Our Overall Health.

The advent of genome sequencing, more advanced technologies, like high throughput sequencing, and access to axenic/sterile animal models, opened the gates to a new understanding of how microbes interact with their hosts. Scientists are learning more and more about potential gut bacterial interactions with the brain and the central nervous system. At the same time, it’s a situation of the more we know, the more we ask.

The Schretter study observed the behavior of conventional fruit flies and flies with no bacteria (axenic), noticing that the no-bacteria flies exhibited hyperactive behaviors. The key question now was, are the differences related to bacteria or no bacteria – or were they just manifestations of age or some other neurodevelopmental factor? After age-grouping the fruit flies, one part of the experiment showed that flies raised conventionally and treated with antibiotics later in life exhibited the same hyperactive behavior as the anexic fruit flies.

But that only led to yet another question: How are the microbes sending signals to the brains of the fruit flies in a way that was changing their behavior? Administration of an enzyme that catalyzes sugar changed the behavior of the behavior of the no-bacteria fly in the same manner it changed the behavior of the conventional fly.

With her article, Krajmalnik-Brown posed a question related to her research: Could it be that the presence of sugar-related substances similar to those used in the Schretter study is what modulates hyperactivity in kids with autism? Or any kids, for that matter, who over-consume sugar?

Can the fruit fly findings be related to human physical and mental health? No, but according to Krajmalnik-Brown it’s a flying start.

Krajmalnik-Brown concludes that studies like Schretter’s are “needed to advance the field.” Further explaining that “studies that shed light onto how microbes are leading gut-brain interactions, and more specifically, which types of molecules are at the center of these interactions are needed.”


Written by: Dianne Price