Professor’s bacteria research helps in fight against antibiotic resistance

Dr. Emilianne Limbrick

Mercer University professor’s research could contribute to the development of new drugs to combat antibiotic-resistant bacteria. 

Dr. Emilianne Limbrick, assistant professor of chemistry, examines naturally occurring compounds and how they can be used to treat bacterial infections that are resistant to other antibiotics. 

“Antibiotic resistance is a problem that we’re seeing, especially in the clinical setting, where bacteria are developing resistance to the antibiotics that we use,” Dr. Limbrick said. “Once they have resistance, those drugs no longer work on them.” 

At least 2.8 million people in the U.S. get an antibiotic-resistant infection and more than 35,000 people die each year, according to the Centers for Disease Control and Prevention. The CDC identifies 16 fungi and bacteria as serious or urgent threats, including methicillin-resistant Staphylococcus aureus, commonly known as MRSA. 

Dr. Limbrick first became interested in this problem as an undergraduate student at Mercer, where she participated in organic chemistry research with Dr. Kevin Bucholtz. When she learned about biosynthesis during a seminar on campus, she was hooked. 

Biosynthesis is when compounds are created by other organisms, such as bacteria, rather than by scientists in a laboratory. 

“I loved the idea of bacteria being able to make these compounds for us,” Dr. Limbrick said. 

Among the main compounds that bacteria make are antibiotics. These antibiotics protect them from other bacteria, and scientists can manipulate them to use against bacterial infections in humans. 

As a graduate student at Vanderbilt University, Dr. Limbrick found a unique compound that is a fusion of two antibiotics and helps prevent the bacteria it’s fighting from becoming antibiotic resistant. 

The discovery out of the Vanderbilt Laboratory for Biosynthetic Studies, led by chemistry professor Dr. Brian Bachmann, recently was published online in the Journal of the American Chemical Society

The fact that one microbe — the soil microorganism Micromonospora — produced two antibiotics fused together was especially unique because, further research in Germany found, it is unlikely the bacteria would become resistant to both antibiotics, Dr. Limbrick said. 

“Essentially, to become resistant, the bacteria have to become resistant to both antibiotics at the same time, which could happen, but would take longer,” she said. 

Dr. Limbrick’s research into antibiotic resistance continued at Mercer, where she and her undergraduate research students recently published research in Molecular Genetics and Genomics. They were looking for a class of antibiotics, called lanthipeptides, that’s never been used in a health care setting and found potential in the Salinispora genus. 

“What we did was essentially look at the genomic sequences of a bunch of different marine bacteria and saw that they had the potential to make a lot of different kinds of this class of antibiotics,” Dr. Limbrick said. “And because there are no lanthipeptides currently being used therapeutically, it likely would not have overlapping resistance with antibiotics already in use. 

“So it could be used in a place where we’ve run out of other options.” 

There’s still a long way to go and a lot more research to be done before these findings can be used to create an antibiotic that can be put on the market. And it can be a challenge to get pharmaceutical companies interested in producing new antibiotics because there’s no financial incentive for them to do so. 

But this kind of initial research is an important step in the process. 

“This is really a place where academia can make a dent. If we had never done the research in the first place, we wouldn’t even know this antibiotic exists,” Dr. Limbrick said, referring to the research she did at Vanderbilt. “If we can do a lot of the research and development legwork, then maybe we can convince (pharmaceutical companies) to take on some of the financial risks that are associated with (developing new drugs).”  

Shailey Shah, a senior majoring in biochemistry and molecular biology, was among the students who published the Mercer research. 

She began working with Dr. Limbrick as a freshman after reading about her research online and then meeting with her to learn more. Shah said they connected immediately. 

“She knew that I was a freshman and that I had very little understanding of proteins and amino acids and stuff, but she was so willing to engage in my curiosity and allow me to ask questions and not know things,” Shah said. “I felt comfortable with her, and I knew that she would help me grow.” 

She said she was “super excited” to find out their work was getting published, especially as an undergraduate student. She finds the work she does in the laboratory meaningful.  

“The more antibiotics that we know of and the more options that we have to fight off bacteria that are infecting humans, the more options we have to get rid of these issues and solve this crisis (of antibiotic resistance),” she said. 


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