SBI Research Feature: New OSU Project Investigates the Biodiversity of Deep Life

Posted: February 11, 2011

Photo of Rick Colwell.Professor of oceanography Rick Colwell is one of the lead investigators on a new pilot grant from the Sloan Foundation to characterize the diversity of life in deep subsurface environments.  The project is soliciting samples from research teams around the globe and will analyze them using pyrosequencing, a state of the art DNA sequencing technique. 

In this short Web interview, Rick describes the project:

Why is it important to learn more about microorganisms living
deep underground?

In terms of basic science, this is really interesting because we’re extending the boundaries of the biosphere deep into the Earth.  At the end of this process we will have a compelling way of understanding where there is life in the Earth and where there is not.  We will know more about where life can survive and that has implications for searches for extraterrestrial life, as well as broadening the view of life on our own planet. 

There was a paper written by Barney Whitman and colleagues in 1998 called the “Prokaryotes: The Unseen Majority.”  He approached the microbial world as a whole and arrived at the conclusion that most of it is underground and most biomass is actually subsurface biomass.  As the science community learns more, his early biomass estimates are being revised downward, but still, we realize that there is huge amount of subsurface biomass and it’s something we know little about.

Related Links

Census of Deep Life Call for Proposals

Deep Life 2010 Workshop White Paper

Deep Carbon Observatory

How did this project come about?

The project is part of the Deep Carbon Observatory – an effort funded by the Alfred P. Sloan Foundation to understand carbon’s chemical and biological roles in Earth’s interior.  One of the focus areas of this effort is “Deep Life.” In March 2010, this effort convened a group of microbiologists, geochemists and geologists to talk about what we don’t understand about deep life and what we really need to understand.  A white paper came out of that meeting that provided this group’s perspective on a way forward. One of the points of this white paper was that we really need to have a better survey of the overall diversity of the organisms of the subsurface and ideally what physical and chemical constraints control that diversity.

I was one of the participants along with Mitch Sogin, a microbiologist at the Marine Biological Laboratory in Woods Hole who was also a co-organizer of the meeting.  Last summer we had the opportunity to write a proposal for a pilot project within the Deep Carbon Observatory and it was funded in November.  Mitch was a P.I. for the “International Census of Marine Microorganisms,” a project also funded by the Sloan Foundation, and that project is very much a model for this one.

What will the project do?

We have a call for proposals out right now (with a February 2011 deadline) to people who are sampling subsurface environments.  It offers the opportunity for successful proponents to submit samples on which pyrosequencing of DNA would be carried out.   This is a rapidly evolving technology that ends up giving you information about the type of organisms in a sample and their relative abundance.  It allows you to examine rare individuals and also gives you information about how close you are to getting an adequate census of the microorganisms present.

We will provide results to the sampling teams and also compile results into a central database with the geologic and chemical information that the research teams collected at their sites. We hope to fund in the neighborhood of 20 proposals with an average of about 15 samples from each one. So that amounts to a couple hundred samples as a starting point to build an understanding of diversity.  Initially, this first round will focus on bacteria and archaea, but we hope to expand to include viruses and eukaryotes in future proposal rounds.

What types of environments are priorities?

We hope to focus on environments that haven’t been studied yet. Historically, there has been a greater emphasis on microbial studies in soils and also subsurface sites in which contaminants are being remediated, so we will not focus on those unless there are some really unique ones.  In a paper I co-authored about seven years ago [1], we tried to classify different geologic settings that would be expected to have totally different subsurface environments.  We classified a dozen deep geologic environments – just a starting point - that deserve to be inspected more carefully for microbial life.

What are some of the guiding research questions for the project?

Ultimately, we’d really like to look at subsurface environments globally. What organisms are truly unique to particular environments?  And what are the pan-specific organisms that you find everywhere?  In some cases people are finding microorganisms that are virtually identical from South African gold mines and marine sediments.  It is becoming clear that the microorganisms see some commonality in these environments, and they are selected for.  We don’t quite understand why -- but there they are.  Hopefully, we will be fortunate enough after a decade of these types of diversity studies, to begin to explain the breadth of diversity and what controls diversity in a range of subsurface environments.


[1] Colwell, F., and R. P. Smith. 2004. Unifying principles of the deep terrestrial and deep marine biospheres, p. 355-367. In W. S. D. Wilcock, E. F. Delong, D. S. Kelley, J. A. Baross, and S. C. Cary (ed.), Subseafloor Biosphere at Mid-Ocean Ridges. American Geophysical Union, Washington, D.C..