Anyone who has worked in a microbiology lab can empathize with the anguish of having a contaminant ruin your experiment. In many cases, such as in clinical laboratories or the food industry, contaminants can prove devastating and challenging to control. When dealing with environmental samples, on the other hand, contaminants are the norm.
Yet microbial contaminants can also be a source of beauty and discovery. The best-known case of a serendipitous discovery based on a contaminant is, of course, the observation made by Alexander Fleming in 1928 of a fungus that inhibited bacterial growth. Careful inspection of this interaction led to the discovery of penicillin, produced by a fungus belonging to the genus Penicillium, and fueled the field of antibiotic discovery for years to come. This case is also a perfect example of how "chance favors the prepared mind," as nicely phrased by Louis Pasteur.
Microbial contaminants are not unique to cultures in the lab. The sensitivity of sequencing techniques, which have been instrumental for surveys of microbial communities, also detects contaminant DNA stemming from sample manipulation and preparation. Unless properly addressed, by including appropriate controls that allow discrimination of unwanted sequences, these contaminants can confound the interpretation of microbiome data, especially when working with low biomass samples. Thus, contamination is of concern in various areas of research.
While microbial contaminants in the lab may be inevitable, they can also be a source of awe and inspiration. Microbes inadvertently growing on our lab media often display a variety of morphological characteristics that are lacking in the pure cultures of commonly known microbes such as Salmonella and E. coli. The Contamination Club (@contamClub) in 𝕏 (Twitter) manages to nicely capture the beauty and ubiquity of lab contaminants (and since recently you also find them on Bluesky: @contamclub.bsky.social). Researchers post pictures that illustrate the unexpected and diverse morphologies of contaminating microbes and can exchange ideas about possible identities and origin of these intrusive microbes. A wonderful place for learning about the unwelcome collateral effects of microbial culturing.
If you have time, take a look at @contamClub (or @contamclub.bsky.social) and, if you feel compelled, contribute with your own photos and ideas. This wonderful tribute to the diverse and adaptable nature of microorganisms also illustrates how contaminants, beyond being obstacles to scientific progress, provoke wonder and inspiration that make them worthy of special recognition.