The Amazon Mycorenewal Project (AMP) is a grassroots project that is experimenting with using mycoremediation to cleanup toxic oil pits left in the Ecuadorian Amazon. Over a 30-year period, the oil giant Texaco (now owned by Chevron) discharged more than 18 billion gallons of toxic oil waste into hundreds of unlined pits in the Ecuadorian Amazon, resulting in extensive environmental contamination and health impacts for local communities. Though Chevron has recently been found guilty after an 18-year-long court battle, the corporation still refuses to pay to clean up its mess.
I interviewed Mia Rose Maltz of the Amazon Mycorenewal Project about her experiences on the ground. Below are some highlights from our interview.
Q: What do your mycoremediation experiments involve?
Mia Rose Maltz: We have found some mushrooms that seem able to bioremediate the toxins; we are doing some bioassays that show that these fungi reduce the toxicity of contaminated soil. We’ve also been doing these ecological surveys that are a little bit different from myco- remediation; we go out and observe what fungi are capable of living and thriving in these heavily contaminated environments.
Our experiments involve three different tiers. One tier is in situ, where we do the remediation right there on the site. Then we do two different types of off-site remediation. One is open-air pits, where we dig out the contamination and mix it with a bulking agent, some sort of substrate. And then we put it into a pit lined with pond liner and then see how this kind of mycoremediation installation performs in the Amazonian environment, being in the open air, exposed to heat and other localized variables. Usually, we put shade cloth or a roof over these open-air pits. Finally, we conduct off-site experiments in boxes, like milk crates, to test specific hypotheses in order to gather data with enough replication, randomization and statistical power that the data collected could eventually be published and presented to the greater community.
Q: How are the mycoremediation experiments going?
MRM: Even though we’ve continued to do some in situ ex- periments, we’ve gotten a little discouraged because some of our in situ installations have been tampered with, either by the military or by the oil companies. We’ve worked long days putting in these installations, and then months later we received word that an oil company had bull- dozed it or dumped a bunch of fill soil on top of it. I really feel that the more valuable in situ experiments will require a long-term ecological research site that doesn’t get tampered with. That is one of our big goals, to be able to buy land or have a long-term lease on land so that we could set up long-term experiments.
That’s pretty much where we are at right now with everything. Still even to this day where Chevron has officially lost the lawsuit, the land that is tied up in the lawsuit is still tied up because Chevron has said that they are not going to pay. We have a really difficult situation because we have people who have had their land contaminated. We have people who have basically signed papers that have given away their right to their land to the corporation that contaminated it. People would love us to come in and do remediation on their land, but we can’t because it is locked up in the lawsuit and we’ve been asked not to tamper with the land involved with the lawsuit. It’s a really tricky situation.
Q: You mentioned bioassays earlier. What are bioassays and why does AMP use them?
MRM: We’ve been putting some energy towards doing plant bioassays, in order to test the efficacy of the mycelial treatments, because we’ve spent tens of thousands of dollars on laboratory analysis and often the results have been inconclusive. The plant bioassay we’ve been developing is cost effective, and the results are easily interpreta- ble. You plant 100 seeds in contaminated soil and compare the viability of the germinated seedlings with seeds planted in a soil that just has an added substrate and also soil that has an added myceliated sub- strate. You compare germination frequencies, the height and girth of the plants and the biomass of the plant. Then you get a sense that the plants that grow better (taller, thicker, germinate more) are indicators that the mycelial treatment has prepared the soil to be more fertile and to be capable of supporting plant establishment in previously inhospi- table soil.
Q: Why are you doing ecological surveys, and how does that fit into grassroots mycoremediation?
MRM: One of the things that I’m really interested in right now is looking at a community approach — the microbial community. Looking at what assemblage — what group of different types of fungi, bacteria and other microbes in combination perhaps with plants — are most effective in remediating the soil. One of the ecological surveys we’re doing is a petroleum pollution gradient. We start off right at the contamination or the plume, and then move away from it, isolating and comparing the microbial community across multiple sites. We are evaluating their functional diversity, functional redundancy, or their re- sponse diversity, because the microbes there could potentially respond to the disturbance of the oil contamination in a diversity of ways. Some may directly perform some type of function that prepares the land for rehabilitation, while others may facilitate others to perform similar or diverse functions. Once we’ve looked at those characteristics, or mi- crobial traits, then we might be able to determine if certain groups we often find occurring together might complement each other and strengthen the resilience of this ecosystem faced with a concentration gradient of surface petroleum pollution.
Q: Are you experimenting with any other grassroots bioremediation tools besides mycoremediation for cleaning up the oil onsite?
MRM: This summer we did a big experiment looking at the combination of oyster mushrooms and actively aerated compost tea. We have been training our Ecuadorian partners in how to make the aerated compost tea and apply it once a week and once a month. In addition to our untreated contaminated controls, we’ve looked at each of these fungal and microbial treatments on their own, and the combination of the treatments. One area we focused on was the order of introduction, so basically what works better. Is it better to add the mycelium and the tea at the same time? Or is it better if we add the mushrooms and then once they are established and you have a very myceliated contaminated substrate, then we add regular applications of compost tea? Or is it better to regularly apply compost tea for several weeks or months and then add mycelium after that?
Q: Why does the Amazon Mycorenewal Project focus so much on scientific experimentation?
MRM: We are just trying to figure out some of the finer points with the work. What works best when you are looking at a spill in a waterway? What works best when you are looking at a spill at high elevation versus low elevation? Or really dry conditions? Or at different times of year? That’s why we’ve been focusing on the science. We don’t want to come in and say we have a panacea that will cure all your problems. That is probably the most unconscious approach we could take. We are being thorough and trying to evaluate stuff like, is bam- boo a better substrate than sawdust? Are hearts of palm wood better than corn straw? Basically what is the best way to do it all? We’re work- ing with local people to figure this out, to make the greatest impact.
Q: What tips would you have for the grassroots mycoremediator?
MRM: Be able to tap into who is there at the site of your contamination: which indigenous microbes and fungi are capable of surviving at the contaminated site. I would do a soil sample, add sterile water and then separate a little filtrate. Basically put some water in there and try to take an eyedropper’s worth of that water and try to grow out some of those microbes and see who is there. You could do this with petri dishes. I would really encourage people to try to see who is already growing in the area where there is a lot of contami- nation, and also I would try some of your usual suspects. There are always a lot of cultures going around of oyster mushrooms, turkey tail, reishi; some of these fungi have been shown to be good at remediating contamination. This is also petri-dish work, however then you can get the cultures to grow on more common substrates. People need to not be afraid of integrating some lab culture into their little myco group, because it really isn’t hard to cook up some media like agar, fill some mason jars with it and use a pressure cooker to sterilize the jars.
Q: How is this sort of petri-dish work helpful to grassroots bioremediators when dealing with contaminated sites?
MRM: I would encourage folks to do that because then they can isolate some cultures and then mix some of the contaminant in. This allows you to find a strain of fungi that is best suited to working with the contaminant and then acclimating it to maximize its effective- ness. If it’s a chemical contaminant, you can soak a little piece of paper (the size of a hole punch) in the contaminant and put it in the petri dish and see if you can get your oyster or turkey tail mushroom strains to grow towards the contaminants. I would do lots of replicates: at least ten dishes with oyster and the contaminant and ten dishes with turkey tail and the contaminant.
I would say maybe one out of the ten of the oyster strains will grow towards the contaminant, and even seem to develop an affinity for that contaminant; that is the culture you want to use as your mother cul- ture and the one that you will expand out to make spawn. So you could ramp it up, let them grow on higher and higher concentrations of con- taminants, and then slowly ramp it down. With this, you are basically acclimating your strain to be able to grow in this really inhospitable environment, picking the strain and the culture that appears to have an affinity to the pollutant, and then grow on a more dilute concentration of the contaminant, in order to maximize its efficacy in more realistic applications of mycoremediation.
Q: Besides the sterile lab procedure, what are some other options for grass- roots bioremediators?
Mia Rose Maltz: At the other end of the spectrum is very low-tech myco-permaculture, using your on-site resources and organic materi- als that are waste streams of others industrial processes. You can get some decomposer (saprotrophic) fungi to start growing on wet card- board or other biodegradable organic materials. Another good strategy is to partner up with local mushroom growers and get a bunch of spent spawn. Bulk it up with substrate and get it growing on cardboard, sawdust, coffee grounds or other litter. And then use that material en masse, like just really go large, high spawn high inoculation, lots of it on the site, keep it moist and out of the direct sunlight if possible. Then you would have a good chance that your mushroom cultures will take.
