Charles Greer Talks about the Practicality of Bioremediation
Special Topic of Oil Spills Interview, January 2011
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Why do you think that 2003 paper has been so
influential and highly cited?
I'm not exactly sure why. It was an international group of us working on this subject area and we used these techniques in very similar papers over the years—essentially just using these molecular tools to characterize and compare contaminated and uncontaminated environments to find out whether these microorganisms are, in fact, present everywhere or if you have to add them in some cases.
What we found was that, in our experience, these microorganisms do tend to be present naturally. Sometimes they're below detection limits, but if you manipulate the conditions appropriately then their numbers and activity increase and you can start to see them where you didn't see them before.
What do you consider the most challenging aspect
to using these naturally occurring microorganisms in remediation
sites?
I constantly remind myself that even though a lot of these organic pollutants can be broken down and that microorganisms have this capacity, there are still so many contaminated sites everywhere and there are still significant challenges in dealing with this. One challenge is that the concentration of pollutants can be so high that it can be toxic even to the organisms that break them down. If it gets above a threshold concentration they can shut down.
"I believe these contaminated sites are contributing to human health problems, although it often takes years or decades for these effects to be noticed."
Sometimes the microorganisms can't get in contact with the compounds you want them to degrade, even if they are there. That's an issue with the oil in the Gulf of Mexico. If you can disperse it, you make it more bio-available to organisms breaking it down. In other words, you increase the surface area and get it into more of an emulsion. When it's just one big agglomerated plume, the relative amount of surface area is very low. So you want to increase the surface area as much as possible to allow degrading organisms more access to these nutrients.
In some cases, the problem is associated with a lack of other essential nutrients or factors needed for allowing this biodegradation to occur. Oxygen can be a key limiting factor. Nitrogen is another essential nutrient and can be a limiting factor. Hydrocarbons are very carbon-rich, but if the microorganisms lack necessary sources of nitrogen, then you have to provide it to make sure the organisms have what you might call a balanced diet.
There are many situations where the contaminated matrix may be very, very impermeable, so it's hard to get things into it and hard to get things out of it. If you have to get nutrients in there to feed the microorganisms, the matrix has to be permeable enough to allow that to happen. These are some of the challenges we deal with whenever we're dealing with contaminated sites.
Are you satisfied with the progress you've made in
this research in the past decade?
I think we've done very well, considering, as you probably know, that funding for the environment is a poor cousin to funding for the health sector. So we're very proud of what's been accomplished considering the amount of bang for every research dollar that's spent. But one area that is still suffering from a huge disconnect is between pollution and human health. People may not understand how strong this connection is, and there's not enough research going on to validate this connection.
Why do you think that is?
"The goal was to make the bioremediation process more efficient and more cost effective, and one way to do that is to target only those organisms that are providing the useful function."
I think it's partly because health effects take many years to be felt or noticed. They're not acute effects, they're chronic effects. If you're constantly exposed to low levels of toxins, it may take many years before their cumulative effects are noticed. I believe these contaminated sites are contributing to human health problems, although it often takes years or decades for these effects to be noticed. It's also important to realize than even if we stop polluting the earth, we keep in mind that we'll still have a considerable amount of cleanup to be done, because long-term effects are still going to be evident.
What would you like to accomplish in your own
research over the next five years?
A lot of what we're doing right now is focusing more on meta-genomics, which is understanding the entire genetic diversity present in the soil, in our case. We're doing a lot of work in the high Arctic in Canada, which is still a relatively pristine environment.
We'd like to develop a really good understanding of the diversity of microorganisms there now, because it's clear that with global climate change there's going to be a lot more activity in this area in terms of exploration and exploitation of natural resources. So that pristine environment is going to change significantly. We want to have a very good baseline of research established, so we're then able to determine the impact of this activity and of global climate change in general.
Bacteria are the smallest living creatures and yet they play a critical role in the air we breathe, the water we drink, the soil in which we grow our food. Without them we don't live. And so they're a powerful indicator of what's happening on the planet, the overall health of the ecosystem. If we interfere with the roles they're playing in some of these basic cycles, we can really mess up the ecosystem.
If we have a good handle on what they're doing now, we'll be able to look
at how some of these key cycles might be affected in the years to come. And
that's what we're now studying: using all these molecular tools and
approaches we've developed to look at entire communities of organisms and
identify how they may change.
Dr. Charles W. Greer
National Research Council Canada
Biotechnology Research Institute
Montreal, Quebec, Canada
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KEYWORDS: BIOREMEDIATION, ALPINE SOILS, HYDROCARBON-DEGRADING MICROBES, ALKANES, AROMATIC HYDROCARBONS, NAPHTHALENE DIOXYLASE GENES, BACTERIAL PATHWAYS, PRACTICAL REMEDIATION, CRUDE OIL, OIL SANDS, SEEPAGE, OBLIGATE OIL EATERS, POLLUTANT CONCENTRATION, BIOAVAILABILITY, SURFACE AREA, NUTRIENTS, KEY LIMITING FACTORS, OXYGEN, CARBON, NITROGEN, PHOSPHOROUS, MATRIX PERMEABILITY, POLLUTION, HUMAN HEALTH, CHRONIC EFFECTS, META-GENOMICS, CANADIAN HIGH ARCTIC.