Bonnie Bassler: Conversations Between Bacteria
Quorum sensing, a form of bacterial communication, shows there is strength in numbers.
Written by Sydney Kim
Dr. Bonnie L. Bassler, born in Chicago and raised in northern California, has become a breakthrough pioneer in microorganism research. Having switched her focus from veterinary medicine to biochemistry as a young adult, Bassler received her B.S. from the University of California, Davis in 1984 and her doctorate degree from Johns Hopkins University in 1990. She is most well-known for her contributions to the constantly-evolving field of bacterial behavior and communication, otherwise known as quorum sensing.
Quorum sensing is a process in which bacteria communicate by secreting and responding to chemical signals called autoinducers, allowing groups of bacteria to collectively act based on the concentration of those signals. This affects the gene expression of behaviors such as bioluminescence, the exchange of genetic information, or the execution of viral invasions in host organisms. For example, only when a bioluminescent population reaches a certain density may it light up as one group. Before the threshold is reached, the bacteria keep dividing but do not exhibit the behavior in question.
Quorum-Sensing Control of Bioluminescence.
The study of quorum sensing began in the 1970s when Dr. J. Woodland Hastings proposed that some sort of signaling molecule allowed Vibrio fischeri bacteria to glow once they reached a certain population density. The genes involved in this signaling pathway were discovered by Dr. Michael R. Silverman, and a similar concept was found with virulence in the pathogen Pseudomonas aeruginosa by Dr. E. Peter Greenberg. Thus, when Bassler joined the research field in her postdoc, scientists knew that the curious communication system was not just limited to the initial discovery about V. fischeri.
Bassler’s paper “How bacteria talk to each other: regulation of gene expression by quorum sensing” published in 1999 detailed her exploration of V. harveyi, another type of bioluminescent marine bacteria that is comparable to V. fischeri. She discovered that the bacteria have sensors, or receptors, tailored to species-specific signals and inter-species signals. The unique proposal that bacteria can be multilingual and that autoinducers play a key role in extensive bacterial communication drew substantial attention from fields beyond microbiology.
Morphology of Vibrio harveyi strains. a Growth of V. harveyi VIB 391 on marine agar 2216E; b luminescence of V. harveyi VIB 391; c growth of V. harveyi VIB 645 on TCBS agar; d transmission electron microscopy of VIB 645 cells obtained from marine broth culture.
Today, the Bassler Lab investigates intra- and inter-species communication and methods in manipulating quorum sensing mechanisms. Several goals include improving the production of antibiotics and developing drugs and therapies that control viral infections caused by pathogens. Researchers are also finding evidence that the LuxR family of autoinducers that Bassler discovered may even impact inter-kingdom signaling, allowing bacteria to interact with viruses and other types of cells. For instance, human gut cells are able to communicate with defensive resident bacteria thanks to quorum sensing.
Bassler’s research in bacteria and her natural role as an educator have not gone unappreciated. Bassler has been a part of the Princeton University faculty since 1994, where she is a Howard Hughes Medical Institute Investigator, the Squibb Professor of Molecular Biology teaching both undergraduate and graduate courses, and the Chair of the Molecular Biology Department. Throughout her scientific career, she has received numerous awards, including the: MacArthur Foundation Fellowship (2002), Wiley Prize in Biomedical Science (2009), Excellence in Teaching Award by the American Society for Microbiology (2014), Dickson Prize in Medicine (2018), and the Genetics Society of America Medal (2020). She was named for the Wolf Prize in Chemistry and the Microbiology Society Prize Medal in 2022, and remains a valuable member of the National Science Board— the organization that oversees national research and education in science, math, and engineering— since she was nominated by former president Barack Obama.
"Bacteria can talk to each other," says Bonnie Bassler. "Not only can they talk, but they are multilingual." And she knows how to speak their languages. Richard Schulman
Three of Bassler’s past students and labmates characterize Bassler’s bright personality and drive for new, first-hand discoveries well. “If you have met her, you know she's a firecracker: full of energy, passion for science, and a comedienne at any event… But she's also a researcher at heart that still loves to hold a petri dish or culture in her hand, working side-by-side with her trainees to analyze a new experimental result” (Van Kessel, et al.).
Sources
Bassler Lab. “Bonnie L. Bassler.” Princeton University, basslerlab.scholar.princeton.edu. Accessed 10 Jan. 2024.
Department of Molecular Biology. “Bonnie L. Bassler.” Princeton University, molbio.princeton.edu/people/bonnie-l-bassler. Accessed 10 Jan. 2024.
The Gairdner Foundation. “Bonnie L. Bassler.” The Gairdner Foundation, 23 Oct. 2023, www.gairdner.org/winner/bonnie-bassler.
Van Kessel, Julia, et al. “The Queen of Quorum Sensing: Scientist, Bacterial Linguist, Professor, Mentor.” Israel Journal of Chemistry, vol. 63, no. 5-6, Wiley-Blackwell, June 2023, doi.org/10.1002/ijch.202300080.
