A Simple and Affordable Biofilm Assay for the Undergraduate Microbiology Classroom

Abstract

Through experience and surveying undergraduate microbiology curriculum, we found that most schools discuss biofilms in lecture classes but not laboratory courses. Biofilms are a concern for both industry and the medical field and should be studied in student laboratories. To study this at an institution, there would need to be an affordable method to assay them. As a sample specimen, Pseudomonas aeruginosa was used as it proliferates into biofilms when it is starved for nutrients, which can be easily simulated in a laboratory environment. Known assays for studying biofilms are expensive, and most departments do not have the materials. In Trypticase Soy Broth (TSB), P. aeruginosa can also be induced to form a biofilm, but the technique is not seen very often because it has not been sufficiently standardized for undergraduate microbiology education laboratories. To account for the absence of specialized reagents, we incubated bacteria for longer periods of time as a means to diminish nutrients or starve the specimen. Using a two-tailed t-test, we were able to show that glass tubes inoculated with P. aeruginosa in TSB for 48 hours were forming distinct biofilms on the glass surface, which is appropriate for undergraduate microbiology laboratory studies.