On this Day: Julius Richard Petri was born

The inventor of the Petri Dish was born on May 31st 1852.

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Agar plates are still essential in modern microbiology. While they are being used less, the life of a microbiologist without them is unimaginable. We owe it all to Julius Richard Petri. He was working with Robert Koch, the legendary microbiologist who gave rise to the idea that microorganism cause disease. At the time Koch was growing bacteria on slices of potato which is far from ideal lab practice. This improved quite a lot with the discovery of Agar by Fanny Hesse. Despite having a new growth medium the great microbiologists of the time were still plagued by contamination. The best solution they could come up with was to place their glass dishes full of agar under bell jars. This didn’t really help.

Then in came Julius Petri. He imagined a world where bell jars weren’t necessary and contamination was a thing of the past. He saw the plates and dared to dream of a way in which they could be individually protected from contamination, while allowing air to get to the aerobic cultures on the plate. He took a glass dish containing agar and then he took a slightly larger dish and put it over the top. Then he…. Well this is all he did, but boy did it work.

 Despite being simple, the impact of this invention cannot be overstated. Isolating pure cultures in the late 1800’s was a huge problem and caused a lot of confusion when interpreting scientific results. The agar plate and the petri dish remain relatively unchanged to this day which is a testament to the simplicity and genius.

 Happy Birthday Julius Richard Petri.

Ben Libberton

Science Communicator, Freelance

I'm a freelance science communicator, formerly a Postdoc in the biofilm field. I'm interested in how bacteria cause disease and look to technology to produce novel tools to study and ultimately prevent infection.