Bacteria On Rocks


Here’s a quiz for you kids. Which of the habitats above possesses the most microbes? A. Fresh Volcanic Basalt on the seafloor, B. Sargasso Sea Water, or C. Farm Soil

A recent study by led by Santelli in Nature provides an answer that may surprise you. It turns out at A and C are the right answer.

We demonstrate that prokaryotic cell abundances on seafloor-exposed basalts are 3-4 orders of magnitude greater than in overlying deep sea water. Phylogenetic analyses of basaltic lavas from the East Pacific Rise (96 N) and around Hawaii reveal that the basalt-hosted biosphere harbours high bacterial community richness and that community membership is shared between these sites.

Now here is the really freaky part. What supports these bacteria? The authors hypothesized and lab evidence supports that chemical reactions of the basalt provide the energy needed to fuel bacterial growth. Volcanic glass is high reactive containing iron, sulphur, and maganese. When oxygen and nitrate in the surrounding water oxidize these elements, chemolithoautotrophic microogranisms could potentially use the free energy associated with these reactions.

Take awhile for that to sink in…because what that means is that our understanding of carbon cycling and deep-sea systems is missing an entire food source and web.

Santelli, C.M., Orcutt, B.N., Banning, E., Bach, W., Moyer, C.L., Sogin, M.L., Staudigel, H., Edwards, K.J. (2008). Abundance and diversity of microbial life in ocean crust. Nature, 453(7195), 653-656. DOI: 10.1038/nature06899

Dr. M (1801 Posts)

Craig McClain is the Executive Director of the Lousiana University Marine Consortium. He has conducted deep-sea research for 20 years and published over 50 papers in the area. He has participated in and led dozens of oceanographic expeditions taken him to the Antarctic and the most remote regions of the Pacific and Atlantic. Craig’s research focuses on how energy drives the biology of marine invertebrates from individuals to ecosystems, specifically, seeking to uncover how organisms are adapted to different levels of carbon availability, i.e. food, and how this determines the kinds and number of species in different parts of the oceans. Additionally, Craig is obsessed with the size of things. Sometimes this translated into actually scientific research. Craig’s research has been featured on National Public Radio, Discovery Channel, Fox News, National Geographic and ABC News. In addition to his scientific research, Craig also advocates the need for scientists to connect with the public and is the founder and chief editor of the acclaimed Deep-Sea News (, a popular ocean-themed blog that has won numerous awards. His writing has been featured in Cosmos, Science Illustrated, American Scientist, Wired, Mental Floss, and the Open Lab: The Best Science Writing on the Web.