Microbiology practical 2025

3 December 2025 Tags: lab mishaps laboratory techniques science humour lab comedy STEM education Teaching Stories

Our latest first-year microbiology practical was a masterclass in creative interpretation. After a thorough introductory lecture, a detailed handbook, and a live demonstration of each procedure, I watched with fascination as my students boldly ventured where no protocol had intended.

The Agar Tattoo

Our first artist decided that labelling the bottom of the plate was far too conventional. Why write on plastic when you have a perfectly good agar surface? The permanent marker inscription is now a permanent part of microbial history, literally embedded in the growth medium. Points for commitment.

The Infinite Loop

The streak-to-single-cells technique is designed to dilute bacteria across the plate until individual colonies emerge. This student, however, discovered a revolutionary approach: why dilute at all when you can refresh your loop in the original culture before every streak? That way you can have longer fun doing your streaks. Not a single colony in sight.

Gram staining without microscope

Gram staining typically requires a microscope to distinguish between pink and purple bacteria. Not anymore! This student applied such an impressively thick bacterial smear that the colour difference is visible to the naked eye from across the room. Who needs magnification when you have volume? However, when I asked him about the shape of the bacteria (cocci or bacilli) he was slightly puzzled.

The Upside-Down Garden

The drop dilution assay calls for placing tiny droplets on the agar surface. This student thought: why not the lid instead? These drops now decorate the inside of the plastic cover like little bacterial chandeliers. Somewhere, an artist is applauding.

The Drigalski Disaster

Finally, the top agar overlay - a delicate pour-and-swirl technique that creates a smooth surface for bacteriophage plaques. But why pour when you can spread? Armed with a Drigalski spatula (a tool specifically not mentioned in the protocol), this student transformed the smooth overlay into what can only be described as microbial cottage cheese.

Of course, mistakes are how we learn, and any protocol is, in part, a guideline and variations are possible. However, following these guidelines may just be slightly less optional than you think.