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BOSTON – Scientists have discovered bacteria from the deep sea with components that are unrecognizable by the human immune system and may hold important properties in the development of cancer treatments and vaccines, according to a collaborative study published in Science Immunology. The findings, published last week, contradict the long-held belief that human cells can recognize any bacteria they come across.

The study, conducted by researchers at the Rotjan Marine Ecology Lab at Boston University, the Kagan Lab at Boston Children’s Hospital and the government of Kiribati, looked at the properties of bacteria from the deep sea collected on a Schmidt Ocean Institute expedition in the Southern Pacific Ocean. 

Bacteria from the deep sea were found to have “immuno-silent properties” that neither harm nor benefit the body and in fact are not even detected by the immune system. Those unique properties could be used to better understand how the human immune system is programmed to attack foreign invaders like bacteria or viruses, and could have great potential in developing novel therapeutic treatments for cancer and other diseases (patents pending).

Scientists spent 20 days onboard the Schmidt Ocean Institute’s Research Vessel Falkor.

Schmidt Ocean’s research vessel Falkor traveled to the Phoenix Islands Protected Area (PIPA) in 2017 with an interdisciplinary team of scientists to explore and document the region’s deep sea ecosystems for the first time. PIPA is the largest and deepest of the UNESCO World Heritage sites and the first internationally recognized Marine Protected Area (MPA) to be established by a least developed nation – The Republic of Kiribati. Over 80 percent of the deep-sea microbes and bacteria collected were found to be immuno-silent to mammals.  

“The diversity of chemical structures expressed by microbial life in the deep sea is totally underexplored and was completely unexpected,” said Randi Rotjan, research assistant professor at Boston University, co–chief scientist of the Phoenix Islands Protected Area, and co–lead author of the paper. “This paper provides the first detailed examples and lays the foundational groundwork, but there is so much more to be done.” 

Victorgorgia soft coral with a chirostylid squat lobster associate in the Phoenix Islands, in Kiribati during the “Discovering Deep Sea Corals in the Phoenix Islands” research cruise. Image made by ROV SuBastian.

Rotjan, whose research focuses on how living corals respond to wounds from predators, says that the interdisciplinary nature of their team was also a major strength. “Studies like these help to demonstrate the value of marine protected areas and conservation. Although most of the deep sea is unknown and unseen, it is clear that it has transformative potential both for the ocean and for ourselves.

Anna Gauthier preserving deep sea samples in liquid nitrogen onboard the R/V Falkor.

“The deep sea may harbor the world’s largest resource of exciting biomolecules to enable new immunotherapies–much larger than Rainforests,” says Jonathan Kagan, PhD, Boston Children’s Hospital. “And importantly, we learned that our immune defenses are not universal–they work best to detect bacteria from the local habitat.”

In June, research vessel Falkor will return to PIPA under Rotjan, who will be joined by PhD student Anna Gauthier, lead author of the paper in Science Immunology, who is co-mentored by both Rotjan and Jonathan Kagan, the Marian R. Neutra, PhD Professor of Pediatrics at Harvard Medical School and the Director of Basic Research at Boston Children’s Hospital. The team will also include a Kiribati collaborator and other collaborators from Boston University and the Woods Hole Oceanographic Institution. In addition to ecologically characterizing the deep sea coral and sponge communities, the team hopes to investigate the innate immune potential of the deep-sea corals themselves, culturing and testing the response of living corals against diverse bacteria while at sea. The results from the current study and potential outcomes from future work help to further justify the importance of marine conservation for the future of healthy ecosystems, and healthy humans.

ROV technician Adam Wetmore controls SuBastian’s manipulator in taking a sample of coral.
About the Organizations

The Schmidt Ocean Institute was established in 2009 by Eric and Wendy Schmidt to advance oceanographic research through the development of innovative technologies, open sharing of information, and broad communication about ocean health. It operates Falkor, a philanthropic research vessel that is made available to the international science community at no cost. For more information, visit

Founded in 1839, Boston University is an internationally recognized institution of higher education and research. With more than 34,000 students, it is the fourth-largest independent university in the United States. BU consists of 17 schools and colleges, along with the Faculty of Computing & Data Sciences and a number of multi-disciplinary centers and institutes integral to the University’s research and teaching mission. In 2012, BU joined the Association of American Universities (AAU), a consortium of 65 leading research universities in the United States and Canada.

Boston Children’s Hospital is ranked the #1 children’s hospital in the nation by U.S. News & World Report and the primary pediatric teaching affiliate of Harvard Medical School. Home to the world’s largest research enterprise based at a pediatric medical center, its discoveries have benefited both children and adults since 1869. Today, 3,000 researchers and scientific staff, including 9 members of the National Academy of Sciences, 21 members of the National Academy of Medicine and 12 Howard Hughes Medical Investigators comprise Boston Children’s research community. Founded as a 20-bed hospital for children, Boston Children’s is now a 415-bed comprehensive center for pediatric and adolescent health care. 

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Video and photos available here.

SOI CONTACT: Carlie Wiener
(808) 628-8666

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