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UNLOCK celebrates International Microorganism Day

After launching our website on World Microbiome Day, the next international event is coming up: International Microorganism Day on September 17th. Another day, another mission? Yes and no. As the existence of two separate days with different names might be confusing, let’s fresh up your mind on microbial definitions. We also explain how you can contribute to International Microorganism Day.

By the UNLOCK team / September 14, 2021


Microbe, micro-organisms, microbiota, microbiome… The terms used are as diverse as the microbial world itself. Microbes are the same as micro-organisms and include  bacteria, archaea, fungi and other microeukaryotes. Micro-organisms are microscopic (micro- is derived from the Greek word μικρος (“micros”) for “small”) organisms, which means that they can be considered living. In that context, viruses are technically not micro-organisms, because they need a host cell to replicate. All microbes in an ecosystem, e.g. the soil or the intestinal tract, are collectively called the microbiota. If you add to this the conditions in the ecosystems, the compounds produced by the microbes and other structural elements, such as viruses, you end up with the microbiome. Still, although microorganism and microbiome mean something different, World Microbiome Day and International Microorganism Day have the same mission: Celebrating the power of microbes!

About International Microorganism Day

International Microorganism Day (IMD) was launched  in 2017 in Portugal. The date of September 17th was chosen, as this marked the day that Antonie van Leeuwenhoek sent a letter to the Royal Society of London with the first description of a single-celled organism, in 1683. As stated on the website, the organization “aim(s) to teach and provide a platform, both online and offline, for microbe lovers around the world to share their passion and knowledge of the microbes in our daily lives.” Four year since its launch, IMD has multiplied exponentially and spread internationally.

Official banner of International Microorganism Day. Source:

How to celebrate

Starting already September 16th, the IMD team organize a 24-hour live stream, including lectures, workshops and fun activities. The livestream can be accessed via the IMD-website or their social media channels. Please find the detailed program here.

Interesting links

If you cannot join IMD, but do want to get inspired by their mission, check out their education resources and blogs. If you want to read more on microbial definitions, read the paper below, published last year by a.o. Hauke Smidt:

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