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Senior Michaela Miller pre­sented her research on biofilms Nov. 4 at Van Andel Research Institute. Michaela Miller | Courtesy

Senior Michaela Miller spent her summer researching biofilm growth of Rhodobacter sphaeroides — an envi­ron­mental microor­ganism with history as complex as its spelling.

She pre­sented a poster sum­ma­rizing her project Nov. 4 at the Western Michigan Regional Under­graduate Science Research Con­ference at Van Andel Research Institute in Grand Rapids, Michigan.

Over the summer, Miller spent roughly 7 – 10 hours a day in the lab at Hillsdale College growing and exam­ining sphaeroides because it is the ancestor to all gram-neg­ative bac­teria.

These are organisms that often happen to be path­o­genic, while sphaeroides itself is not.

“It’s good to study because the more we learn about the way biofilm grows, the more we can learn about pathogens in the end,” Miller said. “It’s a model organism, meaning it is studied often and has good systems that can be applied to other bac­teria.”

Growing organisms in biofilms on cov­er­slips allows for group inter­ac­tions between the bac­terial cells. Certain chem­icals called auto-inducers are sent out and help parts of the organism perform group-based behavior.

“In some cases, this makes them more resistant to things like antibi­otics and harder to kill,” Miller said.

She wanted to study the quorum sensing, or sig­naling systems, of sphaeroides. Miller focused on mea­suring the effect of addi­tional acyl homoserine lactone, a chemical that pre­vents bac­teria from aggre­gating, and its effect on the live-to-dead cell ratio in her biofilms.

When she grew the biofilms, she grew some nor­mally as a control, but she added extra AHL to others. She stained them to dis­tin­guish live and dead cells on the cov­erslip where the biofilms grew.

The stain colored the living cells green and the dead cells red. She then used software to quantify the live to dead cells. Miller found that addi­tional AHL does not seem to have an effect on the biofilm growth, or the live-to-dead ratio of sphaeroides. She orig­i­nally pre­dicted that the addition of AHL would affect the aggre­gation of the bac­teria more.

“I think the reason that that’s not what hap­pened is because the bac­teria does produce this chemical nat­u­rally, and we just added extra, so I’m assuming there’s a threshold con­cen­tration,” Miller said. “When it reaches that, it doesn’t affect it anymore.”

She said the research was still suc­cessful since it was the first time the exper­iment had been done in this par­ticular way.

“A lot of the tech­niques we used in this exper­iment have really not been used, as far as we know, or fre­quently used, outside of Hillsdale,” Miller said.

During her junior year, Miller assisted Stevan Lukich ’17 and her now-research adviser Francis Steiner, biology department chairman, by writing up the live-dead staining pro­tocol in which biofilms could be stained without dis­turbing their growth on the cov­er­slips.

“Her working out that staining pro­cedure was very advan­ta­geous,” Steiner said. “Her quan­ti­tation in her research was excellent, and she realized she needed to nor­malize her data.”

Seniors Genevieve Chiara and Lydia Siepel were both able to use the staining pro­tocol in their research last summer as well while working in the same lab as Miller and seniors Monicah Wanjiru and Steve Sartore.

“I love all the processes asso­ciated with lab work — how you become friends with the people you are working with,” Miller said.

Chiara added that the envi­ronment in the lab was relaxed and the researchers were always willing to help each other out, from taking turns grabbing coffees for the whole group to giving advice about their indi­vidual projects.

“I found a helpful article with a pro­cedure explaining that an effi­cient way to grow biofilms is to replace the media with fresh broth after four hours of adhesion and then let them con­tinue to grow overnight,” Chiara said. “Michaela and Lydia also fol­lowed that pro­cedure.”

Chiara and junior Christine Aush­erman also accom­panied Miller and Steiner to Grand Rapids to present their own posters at the con­ference.

Miller said fellow under­grad­uates, recruiters, and graduate stu­dents were all inter­ested in learning about other people’s research and that it was not a critical envi­ronment. She added that she learned many important things from her summer research.

“Some­times you’re not always going to see what you expected to see or what you hoped to see,” she said. “That doesn’t mean your research is a failure.”

She said she now sees many direc­tions that the project could be taken, which is a success in and of itself.

“In the future, I think we could com­pletely knock out the gene that pro­duces AHL and see sphaeroides truly with AHL and truly without,” Miller said.