Biofilms, thin layers of microorganisms that form on surfaces, thrive in geysers, deep ocean vents, and glaciers. Some clog pipes, gum up machinery, or cause infection and death. Others play an important part in recycling organic waste; help clean toxic spills; are useful in the manufacture of medicines; and power microbial fuel cells, a promising source of electricity.
As important as biofilms are in our day-to-day lives, there’s a lot we don’t know about them. Understanding how they form and adhere to surfaces help scientists learn how to enhance beneficial biofilms and control problem ones.
This summer Beck Ringdahl-Mayland ’13, a biology major, and Andie Quinn ’15, a second year who plans to major in biology, were mentored by Assistant Professor of Biology Shannon Hinsa in projects exploring how the biofilms of a bacterium isolated from the Siberian permafrost adhere to surfaces.
Hinsa became interested in biofilms from extreme environments as a gradute student, expanding her research as a NASA Astrobiology postdoctoral fellow. “In order to better predict where extraterrestrial life might be found,” she says, “we first need to understand how microorganisms survive in extreme environments here on Earth. We work with microbes from the Siberian permafrost, an extreme environment due to low water and nutrient availability, low temperature, and exposure to radiation.”
Quinn says “Our research focused on a trait, biofilm formation, that we believe aids this bacterium [Psychrobacter arcticus] in environmental conditions. This not only helps us understand pathways for survival, but possible mechanisms for survival on other planets.”
Previously Hinsa, Cassandra Koid ’11, and Janna Schultzhaus ’10 identified a key protein the bacterium uses to adhere to surfaces during biofilm formation – an adhesin. Hinsa, Quinn, and Ringdahl-Mayland have begun to characterize factors that impact it. They hypothesized that calcium would decrease the formation of the biofilm, but found just the opposite, and noted differences in the way biofilms formed. They discovered that “cultures grown in the presence of added calcium form networks of cell clusters on the surface, while cells grown without ... form a dense monolayer.” See their poster — The Impact of Environmental Factors on Biofilm Formation by Psychrobacter arcticus — for details.
“Calcium has been shown to increase biofilm formation in some bacteria, while it decreases it in others” said Hinsa. “We are just beginning to understand how. Once we do, we will be able to identify ways to enhance or inhibit biofilm formation of particular microbes.”
Their research has ramifications in the medical field; the adhesin they identified in P. arcticus is in the same family of adhesins as one from pathogenic Staphylococcus, responsible for life-threatening infections. Medical researchers may be able to use what Hinsa and her students have learned about the adhesin in P. articus to identify promising avenues of research as they search for new ways to help prevent or treat staph infections.
Ringdahl-Mayland and Quinn presented their results to an international audience at the American Society For Microbiology (ASM) 6th annual Biofilm Conference in Miami, Sept 29 - Oct 4, where “they were excited to see how their research fit into the biofilm community,” says Hinsa.
While there, the students met two other Grinnellians working with biofilms — Dae Gon Ha ’07, a microbiology Ph.D. candidate, and Snow Brook Peterson ’01, who earned her doctorate in microbiology. “Talking to alumni,” Quinn says, “we realized how little has actually changed. We are still the same sort of awkward people who end up going to biofilm conferences and being excited that we are actually there.”
Ringdahl-Mayland and Quinn are both continuing their research in the spring.
Ringdahl-Mayland found this summer that 12 of 13 other species of Psychrobacter formed biofilms in the same media as P. arcticus, “but what interested me most,” he says, “was that these species of bacteria did not all form biofilms to the same degree, suggesting mutations in genes have accumulated that impact the ability of these species to attach to surfaces.” He is continuing his research in the spring, building a construct to replace a gene they hypothesize is invaluable in biofilm formation, and searching for others that might also affect adhesion.
Quinn is excited to continue to study the effect of environmental factors on the growth of biofilms. “Research involves so many frustrating moments when nothing works,” she says, “that the entire search for answers feels like a detective movie. That makes each moment of understanding extremely meaningful and exciting, even if it’s a little bit of overreacting.”
Their research was funded in part by a grant from the Howard Hughes Medical Institute.