Study Debunks Bunsen Burner Sterilization Efficacy in Modern Labs

For decades, the Bunsen burner has been a staple in biology and chemistry laboratories, with many scientists relying on its flame to decontaminate workspaces by creating convection currents that carry microbe-laden particles away from bench areas. However, a recent study published in August in Microbiology Spectrum suggests this long-held belief may be misguided, revealing that the device is ineffective at cleansing workspaces and can actually increase contamination levels.

Hannah Gavin, a microbiologist at Providence College and co-author of the research, noted that opinions among biologists regarding Bunsen burners have long been divided. While some researchers swear by their sterilization capabilities, others have harbored doubts. Gavin emphasized that despite the apparatus being used for nearly two centuries, no experimental evidence in the scientific literature had previously demonstrated its ability to decontaminate surroundings, leading to a propagation of myths and untested theories.

To rigorously test these claims, Gavin and her team employed Gordonia rubripertincta, a bright orange bacterium easily visible on Petri dishes and uncommon in laboratory settings, to simulate unwanted microbial contamination. The experiments mirrored real-world sources of bacteria, such as dust stirred by vacuum cleaners and particles dispersed through sneezes or shed skin cells.

In the trials, the researchers contaminated the air above lab benches either by spraying a liquid containing the bacteria or by shaking dry towels infused with it. Immediately afterward, they placed open Petri dishes next to both an active Bunsen burner and an inactive one located beyond the flame’s reach. Across almost all trials, the Petri dishes positioned near the active burner collected equal to or greater amounts of bacteria compared to those near the inactive burners.

The sole exception occurred when bacterial contamination levels were orders of magnitude higher than what is typically found in modern laboratories. Amir Mitchell, a systems biologist at the University of Massachusetts Chan Medical School, remarked that the findings could prove to be the “nail in the coffin” for the use of Bunsen burners in contemporary biology labs, potentially ending their traditional role in sterile techniques.