NSF PRFB FY 2023: Does long-term selection for growth on recalcitrant vs labile carbon impact Streptomyces nutrient use or inhibitory phenotypes?

This action funds an NSF Postdoctoral Research Fellowship in Biology for FY 2023, Integrative Research Investigating the Rules of Life Governing Interactions Between Genomes, Environment, and Phenotypes. The fellowship supports research and training of the fellow that will contribute to the area of Rules of Life in innovative ways. This project will explore the impact of soil carbon complexity on microbial growth and interactions between microbes competing for limited carbon resources.

Soil carbon can be broadly categorized as either readily available for microbial consumption (labile carbon) or difficult for microbial populations to metabolize (recalcitrant carbon). In order to utilize recalcitrant carbon, microbes must first break these complex compounds into their building blocks while also defending these building blocks from theft by neighboring microbes.

To this end, microbes which specialize in the metabolism of recalcitrant carbon utilize antimicrobial compounds to prevent their neighbors from stealing these resources. These antimicrobial compounds are also believed to play a significant role in the suppression of soil-inhabiting, plant-pathogenic, organisms. As rising global temperatures are anticipated to increase the relative proportion of recalcitrant carbon within the soil, soil-inhabiting microbes are anticipated to alter their production of and resistance to antimicrobial compounds to further their ability to compete for these complex resources.

Through this fellowship, the PI will further our understanding of how the adaptation of microbes to increasingly prominent recalcitrant carbon will influence interactions between soil-inhabiting microbes. The results of this research will be vital in promoting soil health and will ensure the protection of food crops from soil-inhabiting pathogens. Furthermore, this fellowship will further the training of the fellow, research personnel, graduate, and undergraduate students at the University of Minnesota as well as promote the participation and training of underrepresented groups in science.

In this research, isolates of Streptomyces, a genus of prominent, soil-borne, antibiotic-producing bacteria, will undergo long-term selection for growth in petridishes containing a sole carbon source of varying recalcitrance. Isolates will be dotted on plates and grown until they exhibit sporulation. Spores will then be transferred to subsequent plates for a total of fifty generations of selection on either recalcitrant or labile carbon.

It is anticipated that growth on recalcitrant carbon sources, in contrast to labile carbon, will impart selection for the utilization of a wider range of carbon sources and will increase the frequency and intensity of constitutive antibiotic production. Following fifty generations of growth, the fellow will characterize changes in isolate nutrient use and inhibitory phenotypes as well as genomic and transcriptional changes associated with carbon metabolism and secondary metabolite production.

The results of this project will provide insight into the genomic and transcriptional modifications resulting from selection for growth on carbon sources of varying recalcitrancy. This project will further the fellow’s training in microbial ecology and genomic analysis as well as mentorship and scientific communication. The fellow will also recruit undergraduate researchers to train the next generation of scientists.

In addition, the fellow will develop and conduct outreach events to broaden K-12 participation in science.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.