Thomas Schmidt

Microbes that can reproduce rapidly in times of plenty have an evolutionary stockpile of extra genes that allows them to quickly respond to changing conditions such as oil spills or outbreaks of intestinal diseases.

Energy-hoarding bacteria, on the other hand, have far fewer copies of the genes used to make ribosomes, the tiny factories that assemble amino acids into proteins inside cells.

"Much like the number of pistons in an internal-combustion engine is a proxy for the tradeoff between power and efficiency in motor vehicles, we found that the number of genes that make ribosomes is indicative of ecological strategies of bacteria that favor either rapid or efficient growth," said University of Michigan microbiologist Thomas Schmidt.

"To our knowledge, this is the first robust evidence linking the number of these ribosomal genes to bacterial growth rate and growth efficiency. These findings help establish a foundation for predicting the behavior of microbes in response to the expanding impact of human activities on microbiomes – those associated with the human body as well as in other environments."

The results are summarized in a paper published online Sept. 12, 2016 in the journal Nature Microbiology.

The findings move scientists a step closer to the goal of building predictive models of how complex communities of microbes will behave under various conditions, Schmidt said. That was one of the challenges posed to researchers in May when the White House Office of Science and Technology Policy launched the National Microbiome Initiative, an effort to foster the integrated study of microbiomes across different ecosystems.

Schmidt, a professor in the U-M Department of Ecology and Evolutionary Biology and at the Medical School, attended the May event. U-M is part of the initiative, having committed $3.5 million to the Michigan Microbiome Project, which aims to drive discoveries on how to manipulate the structure and function of the microbiome in the human gut through dietary interventions and to involve undergraduates in authentic research.

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