The Biological Key to Atmospheric Methane Removal with Sam Abernethy and Paul Reginato

Join us as Sam Abernethy, Methane Removal Scientist from Spark Climate Solutions, and Paul Reginato of Homeworld Collective explore why tackling methane could be even more impactful than focusing on carbon dioxide in the near-term. Methane's potent warming potential and short-lived nature make it a high-leverage target for climate mitigation. 

We delve into nature’s own methane eaters—methanotrophs—and how they could help reduce atmospheric methane levels. From bioreactors to genetically engineered plants expressing methane monooxygenase, we highlight promising biological solutions that could reshape methane mitigation strategies.

However, innovation comes with challenges. Sam and Paul discuss the complexities of engineering enzymes for methane breakdown, the hurdles of accurate methane measurement, and the importance of scientific collaboration. These challenges underscore the need for continued research and development in the field.

From agricultural lands to Arctic permafrost, we explore the ethical and technological questions surrounding methane interventions—and the efforts to shape the future of the field, positioning it as a key strategy in the fight against climate change.

(00:00) Introduction to the Climate Biotech Podcast
(01:49) Meet Sam Abernethy
(03:01) Understanding Methane and Its Impact
(06:59) Methane Removal: Challenges and Opportunities
(11:35) Biological Atmospheric Methane Removal
(24:30) Workshop Insights and Future Directions
(39:20) Rapid Fire Questions and Closing Remarks

Transcript

[00:00:00] Daniel Goodwin: Welcome to the climate biotech podcast, where we explore the most important problems at the intersection of climate and biology, and most importantly, how we can solve them. I'm Dan Goodwin, a technologist who spent years transitioning from software and neuroscience to a career in climate biotechnology.

As your host, I will interview our sector's most creative voices from scientists and entrepreneurs to policymakers and investors. 

I'm really excited to share this podcast with our friend, Sam Abernethy from Spark Climate Solutions and with Paul Reginato, the founding scientist of Homeworld. The topic of today is methane. And why are we talking about methane? If you've gotten to climate technology since 2020 ish you're probably familiar with the idea of carbon dioxide removal 

that's a field that had a really great field building moment, where a lot of money and a lot of talent came into the challenge of trying to draw a gigaton of carbon dioxide out of the air in order to find climate stability. What about methane? Methane is coming right behind the heels of carbon dioxide removal 

And as we hope you walk away with today, you'll see that it might actually be the higher leverage, more immediate challenge, if we can tackle some of the major scientific opportunities. Methane eight is 84 times the warming potential of carbon dioxide, but it's also short lived, which means the way we think about the removal challenges is slightly different than carbon dioxide removal.

So we hope going into those nuances are useful. And then hopefully what you'll learn from Sam. is a field wide view of methane removal in general. And what we hope that you'll learn from listening to Paul is the sub challenges of biotechnology to fit inside this larger methane removal agenda. So without any further ado, 

we're thrilled to welcome Sam Abernethy and Paul Reginato for a discussion about biological atmospheric methane removal. PhD in Applied Physics at Stanford University, working with Rob Jackson, where he studied the possibility, space, and constraints of technologies that can remove methane from the atmosphere.

Sam is now a methane removal scientist at spark climate solutions, which is an org we know and love here at home world, where he supports the growth of robust research fields through funding opportunities, stakeholder education, and coordinated research programs. The other guest today is Paul Reginato, and many listeners will know him well.

He's a founding scientist here at Homeworld Collective. Paul received his PhD at MIT, working with Ed Boyden, George Church, and Fei Chen on spatial omics technologies before hard pivoting into roadmapping possibilities for greenhouse gas removal technologies and ultimately co founding Homeworld Collective.

Paul is leading our current program on biology in greenhouse gas removal and the Homeworld Garden Grants application window for greenhouse gas removal is now open until the end of February. Sam, I'm really excited to have this conversation with you. We've worked together for a long time and you and Paul have had a really fantastic collaboration.

 So Sam, who are you? Where did you grow up?

[00:03:04] Sam Abernathy: thanks for having me. I grew up in Halifax, Nova Scotia over on the East coast of Canada. I was just a math kid spent my whole life on the East coast there. Other than a couple of years that I lived in New Zealand.

[00:03:17] Daniel Goodwin: And did you always know you'd be working on the frontiers of greenhouse gas removal technology?

[00:03:22] Sam Abernathy: Absolutely not. No. So I was a math kid growing up. I did my undergrad up in Canada in math and physics. I worked at CERN on particle physics, decided didn't quite love that. And then I was actually at Stanford doing my PhD in applied physics and saw a random opening in Rob Jackson's lab to work on methane removal, which I'd never heard of.

And he took a chance on a physicist who didn't really know anything about climate science. And now here I am somehow a methane removal scientist.

[00:03:56] Daniel Goodwin: There's a funny relationship with physicists to biology, which is that physicists created the field of molecular biology, right? I think the first 19 of 20 Nobel Prizes went to physicists. So there's something that's really delightful about you going from CERN. Searching for the quote unquote God particle to ending up working on methane.

So were you actually working in the particle accelerator?

[00:04:19] Sam Abernathy: Yeah, I did a summer internship there sitting in the main control center for the whole large hadron collider and did data analysis essentially.

[00:04:32] Daniel Goodwin: Wow. And what was this moment where you walk by and you see a poster for methane removal 

[00:04:37] Sam Abernathy: I was somewhat at a crossroads after the first year of my PhD where I had tried a couple of different labs medical physics, biophysics and nothing really stuck. And I'd started to care more about the climate in my personal life, but I'd never properly learned about it or done any work in climate science.

And I happened to see a random posting on the Stanford website, advertising this position and thought that sounds wild and maybe possible. Let's look a little bit more into that and see if it's a real thing.

[00:05:11] Daniel Goodwin: That's really cool. Those moments, that's only kind of sudden opportunity moments are certainly part of a lot of our journeys. So I love that it was a random website that got you into what you're doing now. And I'm going to turn over briefly to Paul.

So everyone knows the voices that they're going to hear today. Paul Reginato, I think the people listening to this podcast know you pretty well. We did a whole episode on meet the founders. But maybe you could also just tell everyone, how you got into methane removal and some of the context that you'll bring into this conversation.

[00:05:39] Paul Reginato: Yeah. I got into methane removal as I was working on our greenhouse gas program here at Homeworld Collective. And, we're always looking for spaces That you know that our home world shaped and that means it's early stage enough that a small organization doing community building and problem identification like home world can actually make a difference.

And that also that there's connections to be made across across communities. We really like. Early stage fields and also fields that, have some momentum that is starting to well up so that it's clear that, people have somewhere to go after they encounter home world.

And the field building work that we do is able to grow And so methane removal really has this characteristic where, Sam will probably talk about it a little more, but, the National Academies, just this summer, put out a report on methane removal advocating for a lot more funding in the space.

And we had gotten into methane removal right before that also through our friendship with spark climate solutions. Um, And so, you know, I'm, I'm coming at methane removal, obviously from the biological standpoint and have really been working with practitioners to try to articulate what the actionable steps are that we can take to move forward in the space.

And we'll talk more about that too.

[00:06:58] Daniel Goodwin: Yeah, I'm really excited about this. You know, I'm putting myself in the shoes of somebody say a biotechnologist who's listening to this and looking for the important work to do and we go straight into talking about methane, but you got to ask the dumb question, which is why methane removal at all.

And so Sam, I'm going to set you up to answer this, which is that Maybe in 2020, we saw this big phase change in carbon dioxide removal. And suddenly that had its moment in the spotlight and is still continuing to grow in a really big way. So I think talking about carbon dioxide removal is now kind of a given. A lot of people that listen to this are pretty familiar with the carbon dioxide removal goals. We talk about the billion ton drawdown, the gigaton capture, and then people talk about the marginal target of About 100 a ton captured.

And so that's driven company creation. That's driven a lot of the field building and the large funds that are have been deployed towards methane. What is the methane equivalent of that? What's the top line? Do we have a marginal goal? I would love to just hear your perspective on that.

[00:07:53] Sam Abernathy: So unpacking the carbon dioxide piece first, The reason why we have a goal of some number of gigatons per year of carbon dioxide removal is because we have this goal for CO2 of reaching net zero. And you need to reach net zero for CO2 because it persists in the atmosphere for centuries and so you need to balance your sources and sinks. Methane behaves completely differently in the atmosphere. So it has a half life of about seven years. So it decays exponentially in the atmosphere and turns into CO2. And so because of that short lifetime, there isn't this same need to reach net zero and the same timescales as CO2. And so the amount of methane removal that we might need depends entirely on the goal that you're trying to achieve.

And the goal that is most compelling to me for methane removal is to have it offset these rising natural emissions of 25 to 120 million tons of methane per year.

[00:08:58] Daniel Goodwin: Great. So playing that back, there's a positive feedback loop happening, and we need to interrupt that through removal.

[00:09:04] Sam Abernathy: Exactly. Yeah, it could be removal, it could be figuring out other ways to reduce other methane emissions, other anthropogenic emissions, but we currently have no way of reducing those rising natural emissions that are caused by this feedback loop.

[00:09:19] Daniel Goodwin: Great. And so where would we be removing these? So I think oftentimes my default is to go immediately to atmospheric methane removal. But I think there's a couple other kinds. I see MED around. Can I once again, just ask the dumb questions of how do we think about removal and the different types of removal?

[00:09:37] Sam Abernathy: Yeah, so when I use the word methane removal, I am just referring to oxidizing methane once it's well mixed in the atmosphere, once it's at its atmospheric concentration of two parts per million, and then I'll use methane emissions destruction when I refer to oxidizing methane at its point sources, before it's emitted when it's at much higher concentrations.

And so the point sources that people are thinking about include dairy barns, coal mines, wastewater treatment plants, and landfills, and then where we might remove it from the atmosphere. Could be pretty much anywhere at this point depending on where you would cite these different interventions.

[00:10:17] Daniel Goodwin: Now it very, I can totally see where we're going to go with this. We're talking about the kind of the biological sources and interrupting the positive feedback loop. And that's where I'd love to tag in Paul here. But before we do, I'd love to just make sure that we're hovering on you and the work that you do.

So your work with spark spans, many atmospheric methane removal pathways with the goal of building the field. So before we go too much further into the specific things I'd love to know about you and the work you're doing at Spark to move this field forward,

[00:10:44] Sam Abernathy: Similar to Paul's answer earlier about why Homeworld is interested in methane removal, because it's small and early and high potential Spark sees the need in methane removal is mostly to advance fundamental science. And so we had a couple of funding opportunities similar to Homeworlds Garden Grants, and we've now funded 20 ish projects ranging from benchtop science to legal frameworks that might dictate how these different interventions could be implemented, to modeling, to field campaigns that measure natural methane sinks.

We also work as a convener, hosting workshops, and bringing together various stakeholders to help move the whole field forward, not just the physical science.

[00:11:28] Daniel Goodwin: 20 teams is a lot. That's super cool. can't say enough good words about Spark as a team. So let's pass this over to Paul. You've been focused on biological atmospheric methane removal. Can we talk a little bit about the subparts inside this methanotrophy?

How do you think about the whole field of biological atmospheric methane removal?

[00:11:50] Paul Reginato: Yeah. Within bio AMR, let's call it there are a few different pathways and they're each quite different, but they all rely on methanotrophy being the methane oxidizing behavior of methane. Methanotrophs, which are these bacteria that can oxidize methane to get energy from it.

They use it as an energy source. And the real special sauce of these methanotrophs is this enzyme, methane monooxygenase, which is the only known catalyst. of methane oxidation at ambient temperatures and pressures. And that might come surprising to some because we know that methane is this really energetic molecule that we actually use as a fuel.

So why would it be hard to react? Methane is very energetic, but it's also very stable. And so it has a big activation energy. So methane is this carbon bound to four hydrogens. The bonds are very symmetric. The hydrogens are held very close to the carbon. And so to get an oxidant in there to actually react with it takes a lot of energy itself.

Of course, like a methane flare will produce enough heat to make a self sustaining reaction, but to oxidize very dilute amounts of methane, where that methane is not generating enough heat to self sustain its own reaction. It's actually very difficult to catalyze this reaction. But figured out to do it.

And a lot of the other AMR technology is like Sam will mention they, they have their own ways of making this reaction happen. 

[00:13:21] Daniel Goodwin: To riff on this, though, I can't help but quote the Bible of biotech, which is Jurassic Park. And there's that famous quote of life finds a way it's absolutely amazing to me that you have an energy rich molecule like methane and only one enzyme has learned to capture it. Do we know much about is there a parallel evolution?

Are there multiple different MMOs? 

[00:13:42] Paul Reginato: There are at least two different MMOs. There's the soluble one and the particulate one. This is getting a little bit into the weeds, but the soluble one is less common in nature but more tractable for biological research. It exists in the cytoplasm and it seems like it has a lower affinity for methane than the particulate one the particulate one is called particulate because it exists in these protein clusters associated with membranes inside the Methanotroph the Methanotroph have these invaginations of their intracellular membrane.

So they have a very high surface membrane inside the cell that hosts MMOs the PMMO particulate, MMO is a really difficult enzyme to study we still aren't fully clear on its catalytic mechanism and is really hard to express recombinant, in other organisms.

So we've never expressed PMMO outside of its host in a functional form. This MMO is this really interesting opportunity where you have this very special catalyst that is the only catalyst that can catalyze this coveted reaction.

But remains mysterious. Even though there's been, great work by Amy Rosenzweig and others on this protein. 

[00:14:56] Daniel Goodwin: So to ask that once again, like as a very dumb question, methanotrophs eat methane. That sounds good towards atmospheric methane removal. But how does it actually fit in? It feels like there's two things that one might solve the problem, but I want to really understand how you guys are seeing this.

So how do methanotrophs figure into the larger atmospheric methane removal agenda?

[00:15:19] Paul Reginato: Yeah there's sort of two categories. It would be like natural methane solutions and engineered. So in the natural group you're basically enhancing natural sinks of atmospheric methane. And so these methanotrophs, they're ubiquitous, really anywhere there's methane, you find methanotrophs, and that includes surfaces that are exposed to atmospheric methane, like soils or trees the Soil hosts these special atmospheric methane oxidizing bacteria, which are bacteria that not only can oxidize methane and grow on methane, but they can grow on atmospheric concentrations of methane.

This is 2 ppm methane, and this is like a really extreme lifestyle to be living off 2 ppm methane and those Organisms also are thought to be living on tree bark. There was recently a discovery of an atmospheric methane sink in the woody surfaces of trees by Vince Gauci and his team. We actually had Vince on the podcast. Talking about this discovery. And it's thought that sink is also mediated by these atmospheric methane oxidizing bacteria. And the soil sink and the upland treaty sink are both. Estimated to be on the order of tens of megatons of methane.

And if we're able to understand what are the factors that cause variation in that methane uptake and how can we, manage land, agricultural land or forests to create the conditions that would. Enhance that methane uptake which could be, just land management practices, or it could be amendments with nutrients that could help the methanotrophs grow better, we might be able to increase the sink on the order of a few megatons, or maybe if we're really successful on the

order of 10 megatons. On the other side, you've got your engineered solutions, like a bioreactor where, it's similar in concept to direct air capture, but instead of pulling out CO2 from the air, you're pulling out methane, and you would have these methanotrophs present on a high surface area material contacting air in this reactor and as the air flows through the methanotrophs would munch on the methane, then finally, there's another biological methane removal pathway that is an earlier stage of investigation. These are all quite early, but plants that are engineered to express methane monooxygenase in their leaves may be able to Remove methane from the atmosphere by air that passively moves over their leaves.

And this kind of approach could also be applied to methane emissions destruction as well. If you express the M. m. O. and Plant roots, let's say rice patties or, have These plants in areas where there are larger methane concentrations then, it's not just an AMR technology, but, these are all quite early stage and we're still trying to figure out whether it's feasible and scalable to do these things.

[00:18:19] Daniel Goodwin: Yeah. I think this is what's so cool about this conversation is that you and Sam have very complimentary roles here, right? Where I look at Sam is leading from the front on the overall field construction of atmospheric methane removal and that larger agenda. And then Paul is leading the charge and the upper bounds of biotech's capacity.

 And I'd love to hear if, use this to prod Sam, like when you're thinking about being, methane removal field builder, how do you think where bio MR fits in and how might it compare with other approaches in your considerations?

[00:18:55] Sam Abernathy: Paul already touched on this, but bio MR. is quite compelling as a potential methane removal pathway, mostly because a lot of these approaches can replicate these natural methanotrophs things that exist already in soils and on plants. And just to put this category of approach that Paul was talking about into context.

among the other methane removal approaches. So these ecosystem methane uptake enhancements, I think of them somewhere in the middle ground between reactors that are like direct air capture and atmospheric oxidation enhancement, which is an intervention into the bulk atmosphere in three dimensions.

And so these ecosystem methane uptake enhancement approaches. are able to piggyback on huge existing sinks over large areas, but they don't have the same cross border impacts of atmospheric interventions that might cause more social and legal issues. And one point I just wanted to add to Paul's description of these ecosystem approaches is that we see such a wide variety in the natural uptake per area, especially in soils, and that to me signals, oh, if there is this order of magnitude difference in how much methane is naturally taken up per area, can we get more of the area to be high uptake?

And that could lead to potentially multiple megatons per year or a 10, as Paul mentioned. 

[00:20:28] Daniel Goodwin: And let me push on this a little bit because one of the core questions I have as an engineer entrepreneur mindset is I'm looking for the engineerable levers, right? And for better or worse, like where we can engineer the sources. But we're really, it's my understanding of the field.

And so please correct me if I'm wrong, is that we're really looking for the engineer ability of the sinks. And that's why I think we got really excited when Vince Gauci's paper came out and it was showing that maybe this is the first like really engineerable, really repeatable methane sink. But the way you were answering that question, the way you were saying it made me think that maybe.

Maybe I'm misunderstanding something. Do we think that there's like large scale sinks that are engineerable today?

[00:21:08] Sam Abernathy: engineerable is a tough word, but I think the soil sink varies so widely depending on whether you're in agricultural land or in forest. And I think we just have a pretty poor understanding of what are the limiting factors that dictate how much methanotrophy per area there is. And so this might be nutrient limitations.

It might be water, it might be pH. There are so many different potential limiting factors that dictate that variety in uptake per area. And once we better understand those, we can maybe better understand how to engineer changes to those over these surface areas.

[00:21:47] Daniel Goodwin: Right. So I'd play that back as it's not engineerable yet. It's pre engineerable. And it's, we're much more in the science phase. Right.

[00:21:55] Sam Abernathy: That's what I'd say. Paul, do you think any of these approaches are at the

[00:21:59] Paul Reginato: no, I would agree. I think it's also worth, Sam, you may be talking a little bit briefly about some of the other methane removal approaches too. So we know what we're comparing to there's enhancement of the atmospheric methane sink.

Yeah. And, that has its own challenges with respect to potential environmental impacts and safety and maybe some advantages with scale that might be nice to touch on.

[00:22:23] Sam Abernathy: Yeah, absolutely. So those atmospheric approaches that you mentioned they are similar to how ecosystems are trying to leverage natural sinks. They're trying to enhance the natural sink that actually causes more than 90 percent of methane to be removed from the atmosphere. And the other 5 to 10 ish percent is in soils and trees.

So the potential ceiling on the scale for those types of approaches in the atmosphere is much higher. These approaches seek to enhance the existing sinks of chlorine and hydroxyl radicals, which are reactive gases that are made naturally in the atmosphere. But the ways that you would seek to enhance those often involve dispersing aerosols into the atmosphere, which comes with a whole host of social and legal issues. And then, on the other end of the spectrum, talking a bit about reactors, you can put a lot of different things in these reactors. There are actually a lot of different ways to oxidize methane, and it's not yet clear which ones will win out from an engineering standpoint, both at atmospheric concentrations and at higher concentrations at methane emission sources. Bioreactors, they seem to me, right now, like other reactors, most promising for emissions destruction. And their main competitive advantage compared to other types of reactors is that you don't need to pump in as much energy to make them work because the methanotrophs do this, but their main disadvantage is that microbes oxidize methane much, much slower than heat based or light based reactors.

So it's a trade off between speed and inputting a bunch of potentially carbon intensive energy to make these heat based and light based reactors work.

[00:24:22] Daniel Goodwin: So now I want to go take a methane gas sensor and put it next to a swimming pool in the summer and see if it's sub two PPM methane. I want to shift this a little bit to there's a recent collaboration that we did between Homeworld Collective and Spark Climate Solutions, specifically diving into this exact intersection we're talking about here, which is biologically enhanced methane removal.

And so I want to turn it over to Paul. I think the whole audience would be really interested in kind of what the purpose of this workshop was. And you did some very cool experiments in field building that were baked into this workshop. So we'd love to start just telling the audience a little bit about that and then we can dive into some of the specific ideas.

[00:25:03] Paul Reginato: Yeah. So this was a really fun workshop we brought together about 35 scientists from around the world working on these bio AMR technologies and the related science. Our goal for the workshop was to output a set of actionable recommendations for what people can work on.

NASM. gave us this report came out in September with some recommendations on. What needs to be achieved in order to overall make further progress on understanding what our opportunities are for methane removal. But, our workshop was almost the opposite kind of recommendation.

It was like, what are the things that Lab size teams can do today to actually make progress on these goals. And those recommendations look a lot different. They're a lot more technical, a lot more in the weeds. We have a practice around communicating these. Kinds of problems already.

We call them problem statements. They show up in our garden grants program. Every application to garden grants has a problem statement that describes an important problem that needs to be addressed and in our problem statement repository. We also share problems that can be addressed by my lab size teams.

And so similarly, we wanted this workshop to output those. So we had all of the scientists collaborate on, first identifying what kinds of problems are important and then really honing in on outlining specific problem statements that they thought were high priority. We've now been refining those outlines into drafts that we're working with the participants to finalize.

And you can find a bunch of those in our problem statement repository and see what we found at the workshop.

[00:26:50] Daniel Goodwin: As a participant in that workshop, I can just say that it was really inspiring everyone I think now knows the high level numbers of 84 times the warming potential of CDR, potentially just a lone methane could be a core to stability in the short term.

I think you can, there's a lot of white papers out there that give that high level. But really drilling down from these like nation scale think tank if you're an amazing biotechnologist, this is what you can do today. It's been really cool to see and to see 35 people from all around the world engage, geek out really hard and then land on things that are basically the introduction.

To papers that we want to see in the world was super cool. And I think I'd love to just ask a couple questions on the science measurement and some of the community challenges that you uncovered that you and Sam uncovered in this. And so we can start with the provocation that Sam was saying, which is that we see a lot of variance in the natural sinks today.

And so there's this idea of pre engineerable, we're not there yet. It's open science. What kind of science do you think we need to understand which of the bio atmospheric methane removal pathways are most viable?

[00:27:55] Paul Reginato: Yeah. So I think. A really important one that came out of the workshop was just getting a better understanding of these atmospheric methane oxidizing bacteria and How their metabolism works, how their genetics work, and what the environmental factors are that influence their thriving or their methane uptake rate.

These are bacteria with a very specialized metabolism. Like I said it's a pretty hardcore lifestyle to live off 2 ppm methane. And these were only discovered a few years ago by Alex Twight at the Arctic University of Norway. And it's a really open question.

What the ways are that we can intervene on these bacteria in the environment. And they really are the point of action where anything we do has to influence them. So like any intervention that we have into an ecosystem has to influence these. atmospheric methane oxidizing bacteria if we want the ecosystem to take up more methane from the atmosphere.

And so we just really need to understand what their way of life is, what are the factors that govern their methane uptake. And these also would be the same bacteria that we might use in reactors as well. In order to understand how to cultivate them and get them to have high uptake in a reactor, we need to understand some basic questions about their biology.

Secondly, there's a question just of quantifying the natural methane sinks and what the magnitudes of those sinks are under different environmental conditions and in different kinds of ecosystems. So there's actually little data on methane uptake in soils and trees compared to data on methane emissions.

What we heard from the scientists at the workshop was that Most work in the past has been focused on quantifying emissions of methane from soils and trees because these systems also can emit methane and relatively less focus on the uptake and the uptake is also harder to measure and that's a challenge to and then finally for methane monooxygenase, this, this enzyme that I mentioned previously, this is such an important enzyme.

It's mediating so much methane uptake on this planet. And yet, we haven't revealed its catalytic mechanism. We're not able to genetically manipulate it in a way that allows us to engineer it or engineer it into other organisms. And so making some headway on taming this protein MMO, would be also Of really high interest.

[00:30:21] Daniel Goodwin: And can we unpack some of the whys? Why is MMO? Is it like a multi part protein? 

[00:30:26] Paul Reginato: PMMO in particular. Okay. There's two kinds of MMOs. There's the SMMO and the PMMO. There's been more progress on taming the SMMO, but even the SMMO requires all these different chaperone proteins to help it fold. And so this is an interesting fact about proteins is that, of course, we know that proteins have to fold from like a string basically into their 3D structure.

Many proteins are not able to fold very easily and organisms will make these other proteins that really exist just to help other proteins And so they're called chaperones. And a protein that requires chaperone help to fold can be really difficult to express heterologously or to express it in other organisms because it doesn't have those chaperones.

And folks have been able to express SMMO in E. coli. But still there's challenges with getting it to replicate the kind of methane oxidation activity that it has in methanatrose. For PMMO, which is the version of NMO that has the higher activity it has this apparently high sensitivity to its immediate environment in the membrane, which it's embedded.

If you isolate those membranes from the cell Even then, you get a substantial reduction in its activity. If you try to express this thing in another organism, people haven't been able to get it to work. And it's still an open question. What are the characteristics of the membrane?

Is it the lipids? Apparently a bunch of the lipids in the environment of this PMMO are not identified. And, lipids can have an enormous Impact on membrane embedded proteins. Also, the membrane voltage or the pH around the membrane can vary a lot between different membranes.

It can have an enormous effect on proteins. And so this seems to be very sensitive to these factors. And so figuring out those details, I think is is really important. And that's what we heard from the scientists at the workshop.

[00:32:28] Daniel Goodwin: am throttling myself not to go on a long rant about all the potential ways we could imagine solving that, but I agree that's a really beautiful challenge. There's two questions left about measurement challenges and community level challenges. And I'd actually love to maybe toss the measurement challenge question to Sam.

So in the carbon dioxide removal world, a lot of that field has been bolstered by people who took it on themselves to be the measurement champions. Right, and I think about our friends at Cascade Climate, I think about Isometric. I think a lot of teams are trying to get there to validate that when you draw down carbon dioxide, you really are storing it.

I think that reduces fraud, et cetera. If I was to apply that one to one to methane, I would imagine that's probably an open challenge for methane, but I don't know. So when I think about that, there are surely methane measurement challenges. Am I thinking about it the right way? And if so, what are some of the sub points inside there?

[00:33:17] Sam Abernathy: I think part of why people have stepped up in the carbon dioxide space is that The carbon dioxide removal technologies are mature. There are companies actively removing carbon dioxide, getting paid for it, and needing to measure and verify that. And actors will step up in that space.

to play that role. Whereas for methane, because it's at least, for methane removal, because it's at least a decade behind, there aren't the same actors stepping up to play that role because there aren't actual interventions being done that would need to be measured. So I think right now the problem in the measurement space for methane removal is somewhat a lack of incentive structures to make those breakthroughs. And then I think the other problem for methane is that any perturbations to methane will also have a number of other impacts, including nitrous oxide, including ozone. And so for measurement of methane removal, you need to actually measure so many different things that it becomes quite difficult to make causal attribution claims about any.

perturbation you do at a field site because you have so many different moving pieces due to methane's interactions with other gases in the atmosphere.

[00:34:36] Daniel Goodwin: And I'd like to push against that or to build in that direction referencing something you said earlier about, I think a big spirit of doing methane removal is to break this positive feedback loop. And so that makes me think that. There's going to be certain points in the world, like the wetlands that you mentioned, would be a source of kind of provable positive feedback loop.

So my intuition, and I'm not deep in the field, so I'm curious what you think about this, it feels like we need to be focusing all our energy in the point source, like the specific areas that are most showing positive feedback behavior. And then tooling that and doing all the engineering in situ there.

That's just the outsiders looking in. Does that, is that the way you think the field is considering, or is it still internal bench lab science before deploying

[00:35:23] Sam Abernathy: Could end up being that we can intervene in those wetlands and freshwater bodies where the feedback loop is happening, but we don't really know any approaches to do that yet. So I think there's active ongoing research to be done to figure out how can we influence those systems. What we do have more control over are areas that are already being impacted for other reasons, like agricultural lands.

And so I think it's potentially much easier to make some methane removal intervention happen over an agricultural land that is already being touched by humans impact rather than going to the Arctic permafrost and trying to do something there.

[00:36:07] Daniel Goodwin: and is that a regulatory thing? Is it a logistics thing? Is it an ethics thing?

[00:36:12] Sam Abernathy: I was thinking of it mostly as a logistics thing. I'm sure there will be other concerns too, but once you start running the numbers on how much methane you can impact and some dollar per ton of methane, it becomes really tough to think about flying out to the permafrost compared to getting that tractor to spray a little bit of more copper somewhere.

[00:36:38] Daniel Goodwin: I don't know. I want to go to the Arctic.

[00:36:40] Sam Abernathy: I'm down.

[00:36:42] Daniel Goodwin: let's this is actually a good time to shout out a two frontiers project. Who has actually also been on this podcast, do amazing job of setting up by like gold standard biotech labs in weird corners of the world. So that could be a fun.

possible collaboration in the future. But I think this is a pretty good segue also to the last question to Paul, which is on the community level. So we've talked about the science limitations. I think we've talked about the measurement and some of the logistic challenges. But let's talk about the community level challenges in the biospace.

What's your take on this?

[00:37:10] Paul Reginato: One thing is that there's. a cultural shift where you have a lot of science that historically has been developed in the domain of basic science and is now being considered as a tool for interventions and technology. And who study the biogeochemistry of Trace gases and these trace gas oxidizing microbes have not historically been part of.

Technology development. And so bringing that technology development mindset into a research community that has historically been pure science is a community challenge of its own. There's also a community challenge around data collection and standardization. So the scientists at the workshop identified the need for standardized protocols for measuring gas fluxes across sites across the world, because there's a lot of measurements that need to be made in order for us to understand how methane flux responds to different environmental conditions, across different biomes, Presently there are a bunch of different types of measurements that are being made that are hard to integrate.

And if we want to collaborate as a community to move towards solutions, we need to have intercomparable data. And that is actually a barrier right now, or at least We heard that from the scientists. There's also a need to raise more awareness amongst biologists and molecular biotech people about some of these fascinating challenges with understanding atmospheric methane, oxidizing bacteria, understanding PMMO there's amazing scientists working on these things already but it's a very small community who are looking at these problems and given the potential for these organisms and enzymes to help us with methane mitigation, not just in atmospheric methane removal, but across a bunch of different methane mitigation technologies it is really worth a look for young biologists.

And I would recommend that, anyone looking for an exciting new problem in climate tech, consider working on some of these problems.

[00:39:19] Daniel Goodwin: fantastic. So to wrap this up, we're going to do the tradition of this podcast, which is that we've got some rapid fire questions and I'm going to ask them to both of you one on one. I'll try to keep it balanced. So Sam, you're going to go first on this one. What's a single book, paper, art piece, or idea that just blew your mind and shaped your development as a scientist?

[00:39:39] Sam Abernathy: Physics of the Impossible by Michio Kaku, which is a book I read in middle school, and it got me hooked on understanding fundamental physics by introducing a bunch of wild, seemingly impossible technologies that we might have sometime in the future.

[00:39:55] Daniel Goodwin: I love it. Paul, what about you?

[00:39:58] Paul Reginato: So there's a paper on these atmospheric methane, oxidizing bacteria by Schmider. It's Schmider 2024. The last author is Alex Dwight. And it talks about the physiological basis for atmospheric methane oxidation, they find organisms are able to live.

It's a group of organisms are able to live on trace atmospheric methane, as well as trace hydrogen and carbon monoxide, so that's where they're getting their energy. And they're also fixing CO2. And fixing nitrogen. And so they're basically growing on air. And I guess they need a little dust particle or something to get there like minerals.

But it's just absolutely amazing and beautiful to me that. air can just be your source of food. And this, this obviously relates to the topic that we're discussing today, but I think it's just so beautiful and surprising. And in that paper, they find that these organisms appear to be living off energy that's lower than the previously thought lower bound to actually maintain the existence of a 

[00:41:02] Daniel Goodwin: The daily dose of we know nothing about biology. I love it.

[00:41:06] Paul Reginato: Very surprising field of science.

[00:41:08] Daniel Goodwin: all right, Paul let's ask you the second question. What's the best line of advice that a mentor gave you?

[00:41:14] Paul Reginato: I would probably say think backward from the problem. When we were in Ed Boyden's lab, you would always be saying, think backward from the problem. And that has been a big part of my work. I've worked on a bunch of different problems and really take that ethos from Ed to try to be open about what the approach is that you take and try to let the problem dictate how you approach it rather than allowing, whatever tool you have in your hand or whatever sort of approach you might be presupposing.

[00:41:44] Daniel Goodwin: Sam, what about you?

[00:41:46] Sam Abernathy: I was going to say a very similar answer my PhD advisor, Rob Jackson, always really emphasized the importance of spending plenty of time pressure testing why you want to do some project. rather than rushing right in. And so I've always spent what some might consider way too much time in the intentional project scoping phase, but it's always been worth it for me in the end.

[00:42:08] Daniel Goodwin: This goes pretty well into the very last question for Sam, just to follow that up, which is that if you did have a magic wand to get more attention or resources into one part of biology or methane removal research. What would it be?

[00:42:20] Sam Abernathy: Such a tough question, but I would say the design of experiments and the development of the measurement tech to facilitate those experiments, That could actually test the efficiency of open system approaches in future field trials once the fundamental science is better understood. And I think we need that development now such that in five years when we're thinking about field trials, they can be done responsibly and effectively.

[00:42:48] Daniel Goodwin: Great. Okay, Paul, for you, if you had the magic wand to get more resources into one part, where would you send it?

[00:42:54] Paul Reginato: Yeah, I would send it to some of these. Foundational open questions that I brought up before around atmospheric methane oxidizing bacteria in particulate methane monooxygenase, they are so important for the methane cycling and have such a crucial role in methane removal. And yet we know so little about them and folks can learn more about open problems related to those by looking at our problem statement repository.

[00:43:19] Daniel Goodwin: Awesome. I think that kind of answers the question, which is where can people learn more about your work, Paul? I think a lot of the great stuff is on the Problem Statement Repository on the Homeworld website. And for Sam for people that are learning about Spark Climate Solutions for the first time where can they learn more about you and your work?

[00:43:36] Sam Abernathy: on the Spark Climate Solutions website, we have a whole page dedicated to a primer on atmospheric methane removal that goes into all these different approaches and the motivation for methane removal. So I'd encourage people to check that out.

[00:43:50] Daniel Goodwin: Awesome. Well, It's been an absolute pleasure to talk with you and to be clear, I've learned a lot in this conversation, so I appreciate it. Thank you Dan. Great 

[00:43:57] Sam Abernathy: to chat, Thank you

[00:43:58] Daniel Goodwin: Thank you so much for tuning into this episode of the climate biotech podcast. We hope this has been educational, inspirational, and fun for you as you navigate your own journey and bring the best of biotech into planetary scale solutions, we'll be back with another one soon.

And in the meantime, stay in touch with homeworld on LinkedIn, Twitter, or blue sky. Links are all in the show notes. Huge thanks to our producer, Dave Clark, and operations lead Paul Himmelstein for making these episodes happen.

Catch you on the next one.