Rhea Johnson and Chris Dedlacek in the lab.

Rhea Johnson, USS (right), with microbiology doctoral student Chris Sedlacek. They work together on Johnson's USS project and they worked on a DUOS (Doctoral-Undergraduate Opportunities for Scholarship) project last year.

Rhea Johnson

Rhea Johnson

Do nitrite-oxidizing bacteria in the environment select for specific ammonia-oxidizing bacteria?

Undergraduate Summer Scholar Rhea Johnson fell in love with microbiology when she took a required course for her major. She added microbiology as a second major along with kinesiology and has now been conducting research with mentor Annette Bollman, assistant professor of microbiology, for the past two years.

Johnson's USS project focuses on microbial ecology — one part of Bollman's research on interactions between microbes and their ecosystems. Bollman examines if these interactions have potential to benefit the environment, such as bioremediation, or cause harm, such as by the production of high amounts of nitrate by nitrification. Nitrate is well known to cause algal blooms and contamination in ground water (as in the recent Toledo water crisis).

Nitrification in nature is a two-step oxidation process: oxidation of ammonium to nitrite by ammonium-oxidizing bacteria, and then oxidation of nitrite to nitrate by nitrate-oxidizing bacteria.

Johnson's research involves characterizing nitrite-oxidizing bacteria. She has conducted competition experiments to see which nitrite-oxidizing bacteria the ammonia-oxidizing bacteria tend to select for and pair with.

She is also investigating if different nitrite oxidizers pair with specific ammonia oxidizers.

She works closely with Bollman's doctoral student Chris Sedlacek, with whom she collaborated in the DUOS (Doctoral-Undergraduate Opportunities for Scholarship) program last year.