Global bacterial diversity is 44% greater than previously thought

Bacteria and Archaea, collectively known as prokaryotes, are the oldest forms of life on the planet, they’ve been around for over 3500 million years and are ubiquitous, meaning they are found all across the earth in every environment, some of which are adapted to living in extreme environments such as hot springs, hydrothermal vents and glacial environments.

Although some bacteria cause a variety of diseases in plants and animals, including humans, bacteria and archaea are key for a variety of environmental processes, including aquatic photosynthesis by cyanobacteria and nutrient cycling in terrestrial and aquatic environments. As well as this, some prokaryotes form key partnerships with animals and plants, such as nitrogen fixing species in plant roots and gut bacteria which help break down food.

Some heat loving (thermophilic) bacteria aggregate and form colourful mats at the Yellowstone national park (© S. Scully)

For these reasons, studying bacteria and archaea is particularly important, to understand their use in medicine and combatting disease, their role in the environment and potential to buffer habitat against environmental change, and their importance in biotechnology. Bacteria and archaea are notoriously difficult to study in the lab, as their tiny size and immense diversity in metabolism and optimal requirements make it difficult to culture them. As a result of this, researchers have turned to genome sequencing as a way of studying these organisms.

Collaboration between researchers across the world has led to the ‘Genomes from the Earth’s Microbiomes (GEM) catalogue’, a database which contains over 52, 000 draft genomes, encompassing a large spread of samples collected from all across the world, including agricultural and natural soils, oceanic and freshwater samples, and sample collected from associated human/animal hosts and symbiotes.

Organisms such as these cyanobacteria leave traces of DNA in their environment, which can be detected using metagenomics (© J.Dazley)

The GEM catalogue has been possible despite the difficulty of bacterial culturing due to a revolutionary technique known as metagenomics. Essentially, organisms leave traces of DNA in their environment, such as lakes, soils, etc., which can be picked up in sampling, meaning that growing the species in the lab is not required to study it’s molecular biology. Through this, samples are sequenced and the DNA of various organisms can be detected, which also gives an idea of the biodiversity of the habitat.


The development of the GEM catalogue has provided researchers with an invaluable resource for studying bacteria, from their ecology, molecular genetics to help tackle disease and understand more about their place in the environment. The database has also shown that these microbes are far more diverse and numerous then we once thought, providing a wealth of information for researchers .