Microbes facilitate many of the natural cycles in plant growth and health, and play roles in many processes in nutrient cycles that control certain environments and climates. Though thousands of these microbes have been identified, the majority of these microbes are still a mystery to scientists and are referred to as microbial “dark matter.”
Study lead author Chris Rinke showing off the DOE JGI’ s single-cell genomics capabilities. Photo by Roy Kaltschmidt, Berkeley Lab.
Steps have been taken by DOE Joint Genome Institute scientists in identifying these unknown microbes and where they fit in the tree of life. In the study published July 14, 2013 in Nature, researchers identified genome sequences from microbes in water samples from all over the world. Scientists at the DOE JGI laser-sorted 9,000 individual cells, extracted and amplified the DNA and reassembled each cell’s genome – a technique referred to as “single-cell genomics.” The team was then able to identify 201 separate microbial genomes that could be attributed to 28 previously unknown branches in the tree of life. The project has brought to light how certain microbes behave in certain ecosystems, as well as their links between microbes in other phyla.
“More than three-quarters of all sequenced genomes fall into three taxonomic groups or phyla,” first author Chris Rinke said, “but there are over 60 phyla we know of.” However, many of the branches in the tree of life are still widely unexplored. The majority of these phyla are still largely unknown and uncultivated, but the scientific community knows that they exist somewhere. The challenge now facing geneticists is identifying where and what they are.