Building a new bacterial ‘tree of life’

Bacterial classification has been given a complete makeover by a team of researchers led by ARC Australian Laureate Fellow, Professor Philip Hugenholtz, based at The University of Queensland, using an evolutionary tree based on genome sequences.

The study relied on a technique called metagenomics, where bacterial genomes are obtained straight from environmental samples, to create a more complete picture of the structure of the bacterial kingdom. Due to advances in sequencing technology, entire genetic blueprints of hundreds of thousands of bacteria are now obtainable, including bacteria that have not yet been grown in the lab.

Taxonomy is the process of classifying living things by arranging them in a hierarchy of related organisms. This technique has allowed the fixing of many bacterial misclassifications, and making the evolutionary timelines between bacterial groups consistent. For instance, the genus Clostridium, historically a ‘dumping ground’ for classifying rod-shaped bacteria that produce spores inside their cells, has been reclassified into 121 separate genus groups across 29 different families.

	The new taxonomic tree presents a standardised model, and is being greeted with excitement by the scientific community.

 

Image (bottom): The ‘tree of life’ for the bacterial world, bacteria’s taxonomy in a phylogenetic tree. Credit: Donovan Parks.