The propagules of Cyanoraptor are considered weird as far as bacteria go. They have an outer compartment bound by two membranes. Researchers suspect that this compartment plays a key role in the attack, by holding and then releasing proteins that break down their prey’s outer membrane and allow it to enter the weakened cell body. This compartment is also how Cyanoraptor gets its species name, togatus, because they appear to be swathed in a robe, or toga. 

Once inside, Cyanoraptor eats away at the prey, growing larger and larger into a sausage-like cell. When it is long enough, this predator starts dividing into many cells all at once, eventually killing the prey and become propagules again, waiting for the next unfortunate victim.

“It is a predator that gets into the cell of their prey and eats them from inside, which is horrendous,” Garcia-Pichel said. “It is really like a microbial horror movie.” 

As cyanobacteria die, all the things that biocrusts do to benefit the desert are gone. Valuable properties like nitrogen cycling, dust trapping and moisture retention are drastically diminished. 

“In general, this means that there could be serious consequences for desert health, fewer nutrients, less stable soil and water retention, so a reduction in time plants and other organisms can be active. With the loss of these functions, organisms that rely on these services, such as plants, may suffer, which could then have further consequences up the food chain,” Rakes said.

This momentous discovery would not have been possible if it hadn’t been for Rake’s tenacity, and her refusal to give in to what at first seemed to be a failure. Fortunately for the future of cyanobacteria, she persevered. 

Her discovery also demonstrated that predatory bacteria can shape the structure and function of microbial communities around the world, that they are not just an interesting biological rarity.

This experience has given her some wisdom to pass on to other graduate students:

“Follow up on those results that are unexpected or even appear to be flat out wrong,” She said. “When I found myself saying, 'That’s weird,' it was often something that I just didn’t understand yet. As Ferran wisely told me: 'In experiments you cannot explain, the microbes are talking to you.'”

The full genome of the newly discovered bacteria can be accessed through the NCBI database under BioProject PRJNA730811. Read more about this paper in Science; it was highlighted as a part of their “in other journals” section in a note titled “Little fleas have lesser raptors.” Rakes and Garcia-Pichel are affiliated with the School of Life Sciences (SOLS) and with the Biodesign Center for Fundamental and Applied Microbiomics. This investigation was done in collaboration with Shannon Lynn Johnson, a scientist at Los Alamos National Laboratory and a SOLS doctoral alumna.

Anaissa Ruiz-Tejada

Graduate Science Writer, School of Life Sciences