A team of Cornell University scientists will soon attempt to capture and grow methane-producing microorganisms which thrive in the depths of highly acidic, oxygen depleted bogs and wetlands. The scientists, recipients of an $837,000 Microbial Observatory Grant from the National Science Foundation, will be the first to do so if they succeed.
“We know they’re out there but no one’s been able to culture them,” said Prof. Stephen Zinder, chair of the Department of Microbiology.
Prof. Joseph Yavitt, natural resources, and co-collaborator on the project, agrees.
“They’re very ancient organisms [and] very difficult to culture and study. A lot of people have studied their ecology, but not the organisms themselves,” he said.
The scientists are interested in these organisms — termed methanogens for their ability to produce methane — both for knowledge of their basic biology and in order to understand what their methane production contributes to environmental change, both now and in the future. As global temperatures rise, increased microbial activity could result in more methane ouput.
Methane is a greenhouse gas, which acts to keep heat from escaping the atmosphere. According to Environmental Protection Agency (EPA) estimates, methane is 21 times more effective at trapping heat than carbon dioxide.
Worldwide, the top source of methane production is livestock, followed by rice cultivation and leakage from natural gas and oil production. Other major contributors include coal mining, sewage treatment, landfills, and even termites. Of these causes, human-related activities produce 70 percent of the methane emissions currently entering the atmosphere. While these contributions have been well studied, other sources have been neglected.
“We don’t have a really good study of the methane in the environment that comes from natural sources,” said Yavitt.
Sampling sites for this study will include bogs and quagmires around Ithaca, including McClean Bog, Michigan Hollow (in Danby State Forest), and a quagmire in Tully. Some of the sites are the remnants of glacial action that took place over 13,000 years ago and have been accumulating organic matter ever since.
These habitats are also populated by carnivorous pitcher plants, sphagnum moss, lichens, and fungi, and it is their decaying remains that nourish the methanogens which dwell deep in the bog.
Studying organisms unable to be grown in the lab has led to a difficult situation. The production of methane, which is actually a waste product of these organisms, has largely been the only way of studying their populations.
“Imagine you go to a zoo and see an animal and its poop — and you then try to study the animal from the poop. That’s essentially what’s been done,” said Yavitt.
In order to correct this situation, the scientists will first have to figure out how to grow the organisms in the lab.
“We believe we’ll be able to culture them now based on our studies of the environments they live in and on their relatives that we have been able to culture — for example, those from sewage sludge and landfills,” said Yavitt.
The key to success may lie in careful selection of the nutrients provided to the organisms, which are kept alive in substances called growth media.
“We’re going to try to make growth media that is more like their habitat. Rich media inhibit a lot of organisms that live in natural habitats. We’re going to try and use more dilute media and ones with extracts from the environment they grow in,” said Zinder.
Adding to the degree of difficulty is the fact that these organisms are obligate anaerobes — that is, they can only grow under strict oxygen-free conditions. In this case, that means handling soil samples in a special device called a “glove box”, which maintains the proper environment.
The reserachers must then carefully sift out the organisms they’re looking for from the rich diversity that exist in their samples.
“The bog soil is extremely difficult to work with. You start with an enrichment to put the organisms in conditions they like and then you try to tease them out,” said Suzanna Brauer grad, who will help with the project.
Once cultured, the scientists hope to see how methanogens will respond to the changing conditions that dominate our world today.
“We can study them in the lab and see how sensitive they are to global warming, pollution, draining of the area, etc. We want to study them under a range of conditions,” said Yavitt.
With data in hand on how methanogens respond to these conditions, researchers can then integrate this knowledge into conventional climate models, which can help make predictions about the future climate.
“The whole goal is to be able to forecast future concentrations of methane in the atmosphere and thus its contribution to global warming,” said Yavitt.
Given their ability to survive under harsh conditions, methanogens may also have a future in bioremediation of contaminated sites.
“Some habitats — especially polluted ones — can be pretty acidic. These organisms could be able to break down [pollutants] under these conditions,” said Zinder.
Archived article by Jennifer Frazer