In our latest podcast episode, we are discussing Carbon turnover in the deep biosphere, its relevance to modern society, how it takes place and how it influences life on the surface.
For that, Katarina Josifovska interviewed Prof. Dr. Alexander Probst, associate professor for “Aquatic Microbial Ecology” at the University of Duisburg-Essen
[Music] hello everybody and welcome to another episode of the European young chemist Network podcast in today’s episode we are going to talk about the carbon turnover in the Deep biosphere why it is relevant how it takes place and how it influences the life on the surface for this we have invited Professor Alexander Propst associate professor for aquatic microbial ecology at the University of diesburg Essen Professor props received his PhD at the ARA Center at the University of rensburg Germany prior throughout and after graduate school Professor props worked as a bioinformatics scientist at second genome Inc where he contributed to more than a 100 different microbium studies after doing a post talk in Jill banfield’s Lab at UC Berkeley he was appointed as professor at the University of dibber Essen now Professor props leads a team of scientists investigating carbon cycling in the Deep Continental subsurface he has authored more than 80 peer-reviewed Publications acts as a reviewer for many journals and is the chair of the environmental microbiology panel of the German Society of microbiology where he’s also a member of the scientific Advisory Board hello everyone I’m here today with a professor for aquatic microbal ecology in University D Boran Professor Dr Alexander probes Alex welcome hi Katrina we decided to talk about carbon turnover in the Deep biosphere a little of a bit of background stories worth seeing here and what is a carbon turnover and where does it come from how does it take place thanks that’s that’s a really great question so carbon turnover is is a it’s a rather colloquial phrasing that I often use it’s um more or less also carbon cycling it is uh the transformation of inorganic carbon to different sorts of organic carbon and vice versa so um and that process is usually mediated by different forms of life it is so an essentially a carbon cycle um going completely from oxidized carbon that is CO2 to reduced carbon like sugars or even methane and uh this carbon torn overa as I said is mediated by many different forms of life in the subsurface and these forms of life is what people call the Deep biosphere deep because it’s down there way meters below our feet and biosphere because it is consistent of uh forms of life why is the carbon turnover relevant in that deep deep biosphere so if you look at the distribution of carbon across our globe and compare Earth’s critical Zone meaning the zone that we live in where plants exist where we have uh the top layer of the ocean where we have rivers and so on and we if we compare that critical Zone to the subsurface it’s like comparing an elephant to a mouse regarding the carbon that is there so if you go to the to the Deep um subsurface there are about 20 billion tons of carbon and this is mainly inorganic carbon and of course if you compare that to what we have in the critical Zone and what is currently affecting our climate this is a gigantic proportion and that carbon of course when it’s turned over going from inorganic to organic matter is a of course of great relevance regarding the overall carbon cycle on our planet and uh the majority actually is inorganic carbon and it’s actually not uh fossil fuels because a lot of people think that the Deep um subsurface houses mainly fossil fuds but they actually only make a really minor proportion of the entire carbon in the Deep subsurface and what this relates to is actually how carb carbon is stored and transformed and that actually provides Us New Perspective uh not only on Earth’s history but also helps us to understand industrial processes like carbon capture and storage where people try to capture carbon dioxide that that is produced mainly in industry and then pump it to the Deep subsurface and try to store it there so it doesn’t interfere with our climate change so that to happen we need a sunlight as the main energy source for life on the planet but from where we have that energy there is no sunlight yeah sunlight is the main energy source for Earth’s critical zone so it excites electrons for processes like photosynthesis and that source of course doesn’t exist for the Deep biosphere however there are other reduced and oxidized compounds mainly minerals that can be used by microorganisms to create Redux potential and perform essentially the same mechanism for carbon fixation as plants employ on the surface of our planet so particular zones where reduced minerals mix with for instance oxidized seawater at the mid ocean ridge create a suitable area for microbial life the methods for identifying such processes are manifold so of course people initially started to take microorganisms from the environment M cultivate them in the lab and try to see if they are really fixing carbon nowadays people actually measure those things in situ in actually in the Real Environment uh to determine what the carbon turnover is and how microbes actually use oxidized and reduced compounds to uh create energy for carbon fixation so in other words the microbes are eating the minerals sort of they are transforming the minerals so they’re for inst for instance oxidizing or reducing minerals yes and that’s how they get uh that’s where they get the energy from another great energy source by the way for instance is hydrogen so hydrogen is released for instance as a minor proportion by mental degasing so gases that um come from the mantle and that minor proportion of hydrogen can fuel a lot of microbial Life In The Deep biosphere and those that hydrogen is then oxidized of course and with that energy is produced and is that process very slow or very fast compared to the carbon turnover that is that happens in the surface that is a very very uh good question that researchers are actually currently investigating it is generally believed that the that the Deep subsurface is very slow growing microbes are extremely inactive but what we do find and that’s something that we have discovered during our research is that there are certain hot spots in the Deep biosphere where microbes flourish and they actually reach activities and carbon fixation potential of microbes here in the critical zone so they won’t exceed the biomass turnover of plants of course on our planet because because plants have a huge amount of biomass however their activity is as close to microbes of the critical Zone as possible and those hot spots in the Deep biosphere are mainly those areas where for instance mantle degassing occurs where you have high CO2 partial pressure and uh where you have hydrogen available as a A reduced compound that can be oxidized and that actually then fuels microbial life very very interesting and you mentioned that you investigate and which method you used for that yeah um there are different sorts of methods so the first question that people always ask when they explore the Deep biosphere is what microbes actually are there and what we mainly use are meth me that people refer to as Next Generation sequencing which would be decoding the genetic information of microorganisms like the DNA and the RNA and with that DNA available we can build phenetic trees we can build the tree of life and see which type of microb do we find down there and the interesting part is that when you go to the Deep biosphere you always find fascinating new microorganisms and then the next step once we know which microb it is we predict what can those mic microbes do and ultimately then also want to know if these microbes are really turning over carbon one way to do this for instance is to um analyze the isotopic ratios of carbon in for instance the biomass or directly in the lipids and with that you can determine if carbon fixation had been taken place or if the carbon mainly comes from organic sources in their respective ecosystem MH so does that the carbon fixation impact life on the surface or not and how if yes so carbon fixation per se is of course to a certain degree important because it captures for instance CO2 released from the mantle to a certain degree and uh transforms it to biomass but there are also many other processes within the carbon cycle in the Deep biosphere that play an extremely crucial role for our daily life actually so one example was actually the discovered in the late ’90s by a very famous German chemist uh his name is Kai endri would be probably nice to also invite him for a podcast and he could probably expand on it so what he discovered was uh the oxidation of methane by microorganism in the in deep ocean sediments so in deep ocean sediments you have a constant geologic release of methane and that methane can precipitate as methane hydrate at the seaf Flor due to pressure and temperature but most of it is would essentially also be released to the atmosphere and methane is a way more important greenhouse gas than CO2 so if that accumulated in the atmosphere of course our climate change would have happened millions of years ago however microorganisms actually turn that methane into CO2 which is then of course dissolved as carbonic acid in in sea water or also released to the atmosphere and depending on which study or report that you use about 40 to 70% of uh the methane that is released at the sea Flor is oxidized to CO2 and that carbon turnover actually makes Life as we know it possible at the surface and that I think is one of the biggest examples how the Deep biosphere actually impacts our daily life and how we experience our life on Earth nowadays wow so I can see you’re having quite a fun doing investigations on the topic so what fascinates you in your work the the interesting part about studying the Deep biosphere or studying microbes in the subsurface and and trying to to understand how they um mediate carbon turnover is actually that you constantly discover new microbes the the Deep subsurface is something that we do not have constantly access to like if if we want to study soil well I can just go to my backyard and uh scoop up a little bit of soil and then analyze it if I would like to study an ecosystem that is like in 1 and a half kilometer depth I cannot just go there and drill down there for 2 million uh for 2 million euros right because you would first need to find someone who gives You2 million euros and that’s why the Deep biosphere is extremely little explored so whenever we have the chance to sample the Deep biosphere or to get sample material we always find extremely new microbes and most of their genes actually have not been discovered before and they also bear great potential for biotechnological use for instance uh during my post talk one of uh one of my co-workers actually started to explore uh crisper Cass systems in one of in one of my data sets and we found actually very very new crisper cast systems that are way more streamlined than regular crisper cast systems and will hopefully be applied in biotechnology at a certain point um another example is that some microbes actually have tiny uh nanog grappling hooks like the smallest hook um that we have discovered on our planet so far it was just a 20 nanometers in width and they can actually they can be used to adhere to ecosystems and what what we are trying to do is to cultivate those microbes in the lab to eventually make those hooks accessible for biotechnology because you could imagine many sorts of things that you can do with Nano grappling hooks like um Nan create Nano velcros or such sort of things and so there is not only the drive to discover new forms of life there’s also uh the the great potential for biotechnological applications wow but um it’s true that it was believed for example in the past that there can be no life deep down in the B house there in the subsurface right yeah now you’re discovering new life and um it’s really amazing we wish you uh very very luck in your further research and hopefully in some years to make another podcast and to tell us something more about what you have discovered thank you so much Katarina I really enjoyed this interview thank you again Alex and special thanks to our listeners hello everybody it’s Mark kada here again we hope you enjoyed our podcast and stay tuned for our next Edition [Music]