Wealth of unexpected new microbes expands tree of life

An artistic representation of the tree of life

An artistic representation of the tree of life, with many new groups of bacteria on the left, the uncultivable bacteria at upper right (purple), and the archaea and eukaryotes (green)—including humans—at lower right. 

Illustration by Zosia Rostomian.

Imagine that you suddenly discovered 1,000 new ancestors or relatives in your family tree. That’s essentially what’s happened to the “tree of life,” a system of illustrating how earthly life has evolved and diversified.

Over the past 15 years, UC Berkeley researchers have discovered more than 1,000 new types of bacteria and archaea lurking in Earth’s nooks and crannies. Now, the tree has been dramatically restructured to account for these newly known microscopic life-forms.

The revised tree, published online in April in the new journal Nature Microbiology, reinforces once again that the life we see around us—plants, animals, humans, and other so-called eukaryotes—represents a tiny percentage of the world’s biodiversity.

“The tree of life is one of the most important organizing principles in biology,” said Jill Banfield—a UC Berkeley professor of earth and planetary science and of environmental science, policy, and management, and one of the article’s co-authors.

Much of this microbial diversity remained hidden until the genome revolution allowed researchers like Banfield to search directly for genomes in the environment, rather than trying to culture microbes in a lab dish. Many of the microbes can’t be isolated and cultured, because they’re not able to live on their own: They must beg, borrow, or steal stuff from other animals or microbes, as either parasites, symbiotic organisms, or scavengers.

“The new depiction will be of use not only to biologists who study microbial ecology,” said Banfield, “but also to biochemists searching for novel genes and researchers studying evolution and earth history.”