A CURE for Physiological Characterization of Bacterioplankton in Liquid Culture

Bacterial characterization is an important aspect of microbiology that includes experimentally determining growth rates, environmental conditions conducive to growth, and the types of energy sources microorganisms can use. Researchers use this information to help understand and predict an organism's ecological distribution and environmental functions. Microbiology students generally conduct bacterial characterization experiments in their coursework; however, they are frequently restricted to model organisms without ecological relevance and already well-studied physiologies. We present a course-based undergraduate research experience (CURE) curriculum to involve students in characterization of previously untested, ecologically relevant aquatic free-living bacteria (bacterioplankton) cultures to identify the usable nutrient substrates, as well as the temperature and salinity ranges conducive to growth. Students use these results to connect their organism's physiology to the isolation environment. This curriculum also exposes students to advanced microbiology methods such as flow cytometry for measuring cell concentrations, teaches them to use the programming language R for data plotting, and emphasizes scientific communication through writing, speaking, poster creation/presentation, and social media. This CURE is an attractive introduction to scientific research and was successfully tested with 187 students in three semesters at two different universities. Students generated reproducible growth data for multiple strains across these different deployments, demonstrating the utility of the curriculum for research support.