Evolutionary competition among microorganisms can benefit human health too, Bashey-Visser said.

"Other studies are increasingly tracing situations where one person becomes sick while another doesn't to the presence of beneficial microorganisms," she said. "These probiotics, or 'good bacteria,' prevent infection by attacking disease-causing bacteria."


The use of less virulent bacteria to competively defeat disease-causing microorganisms is the basis of "replacement therapies," Bashey-Visser said. The process is similar to new treatments such as fecal transplants, in which a stool sample from a donor is introduced into the gastrointestinal tract of a patient through colonoscopy, which can restore a healthy microbiota. The procedure is an increasingly common treatment for life-threatening conditions such as Clostridium difficile infection, or CDI.

According to Monika Fischer, an assistant professor of clinical medicine at the IU School of Medicine in Indianapolis who established one of the first fecal transplant programs in Indiana in 2012, doctors who perform the procedure, which colonizes patients' "gut flora" with healthy microorganisms, report a cure rate of about 90 percent.

At IU Bloomington, Bashey-Visser's research focuses on a surprisingly small species whose strange life cycle may also yield big lessons about how competition among bacteria affects biology.

The species is an insect-killing nematode in the genus Steinernema whose life cycle depends on bacteria. These roundworms, which carry a small amount of bacteria in the genus Xenorhabdus in a pouch off their intestines, cannot grow into adults until they enter an insect and release the bacteria. The bacteria helps kill and digest the insect, creating an environment in which the nematode can mature and reproduce.

"The life cycle of these tiny parasites is pretty crazy and, in many ways like our own dependence on microorganisms, wouldn't be possible without bacteria," said Bashey-Visser, whose work has revealed that competitive dynamics among the bacteria in these insects can maintain a diversity of strains within a single species.

"The more we understand these dynamics, the more we will understand about genetic diversity and preserving biodiversity," she added.

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All of the insects and nematodes analyzed in Bashey-Visser's research were collected at the Moores Creek location of the IU Research and Teaching Preserve, a 1,600-acre area of protected natural resources used to support research, teaching and outreach at the university.

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