Russell's Blog

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Thermophiles workshop overview

Posted by Russell on August 23, 2010 at 12:27 p.m.
After landing at the airport, we crammed our equipment and ourselves into a taxi-van, and returned to the little apartment we stayed in before leaving for Uzon. There's a washing machine there, so we ran as many loads of laundry as possible.

Back at the apartment in Petropavlovsk, we tried (and mostly failed) to get the smell of hydrogen sulphide off of us.

Then next day, we piled into another taxi-van and rode to the Flamingo Hotel, where the workshop will start tomorrow.

Update : Below is a summary of my favorite talks at the workshop that I wrote on the flight back to California.

There have been a number of really exciting talks here at the workshop, and I can't summarize all of them. So, here are a few talks that have kept me thinking.

Sergey Varfolomeev : The youngest natural oil on Earth

Carbon-14 dating indicates that Uzon contains petroleum-like oil that is less than 50 years old. Very similar compounds were obtained by low-temperature pyrolysis of cyanobacteria and microalgae isolated in the vicinity to the hydrocarbon sample sites.

Albert Colman : Chemistry and geobiology of life in hot carbon monoxide

One of the key events in the establishment of our existing ecology was the development of an oxygen rich atmosphere. This process occurred in several stages, and one of the key stages marked the end of the Archean eon. Archean ecosystems are thought to have included oxygen-producing organisms, but during the Archean eon there were enough free reducing compounds in the atmosphere, ocean and soil to consume all the oxygen they produced. The Archean eon ended when these chemical oxygen sinks were finally overwhelmed, and oxygen started to build up in the atmosphere. In order to understand how and why we have an oxygen-rich atmosphere, it is important to understand how the Earth's atmosphere worked during this period.

Albert and his group are studying the role of carbon monoxide in the Archean atmosphere. There are a variety of organisms that exist today (particularly in volcanic environments like Uzon) that grow on carbon monoxide, and for this reason, the biosphere is usually treated as a sink for carbon monoxide. However, there are also organisms that produce carbon monoxide as a waste product, and so the coupling of atmospheric carbon monoxide to the biosphere in Archean climate models needs to treat the biosphere as a source and a sink to properly capture the dynamics.

I find all of this to be fascinating. It's very important that we get a handle on this stuff; mankind has been conducing a huge, uncontrolled experiment with the Earth's atmosphere since around 1820. Learning about other such "experiments" in Earth's history (in Archean, by microbes rather than humans) is pretty important.

Evengy Nikolaev : Mass spectrometry

I had no idea there were so many kinds of mass spectrometers! I guess that's what I get for my background in theoretical physics. My inclination is to write

and call it a day. Mass spectrometry, to me at least, has always meant this :

Schematic of a basic mass spectrometer.

If you stick some ions in a constant magnetic field, their orbital frequencies will depend only on their mass and charge. So, you just aim your beam of ions through a magnet, and all your ions will segregate out like colors in a rainbow. Done. High school physics, right? Wrong!

Evengy's talk was like looking up a recipe for pancakes and discovering that there are breakfast, lunch, tea, and dinner pancakes; that they can be made from fifty different grains and pulses; and that there are pancake recipes suitable for every occasion ranging from a quick bite while driving to work in the morning to the main course of a king's coronation. That's a lot of mass spectrometry!

Juergen Wiegel : Interspecies heterogeneity and biogeography of Thermoanaerobacter uzonensis

I'm really interested in biogeography generally, and so I was waiting for this talk. The Baas-Becking hypothesis that "everything is everywhere, but the environment selects" has been one of the key ideas in microbiology. As gene sequencing has gotten more powerful, it has been possible to test this hypothesis with increasing confidence. Juergen presented some findings that take another step toward disproving hypothesis and establishing the importance of locality in evolution.

Basically, his group at the University of Georgia obtained 16s small subunit rRNA sequences from Thermoanaerobacter uzonensis isolates collected in different spots in Kamchatka. The collection sites ranged from a few meters apart to about 300 kilometers. It was found that divergence among the sequences correlated positively with geographic distance.

The environment does indeed select, but the Baas-Becking hypothesis only holds for fuzzy definitions of "everything" and "everywhere."

Anna Perevalova : Novel thermophilic archaea of order Fervidicoccales - diversity, distribution and metabolism

I had been bugging Anna during the field expedition to tell me more about Fervidococcus fontis, which she discovered. F. fontis grows between 55C and 85C, which is an unusually wide range. The genome has recently been sequenced, and she presented some of the preliminary results from the annotation.

I still find it mysterious how one sets out to find new species (in this case, a new genus). Anna works in Elizaveta Bonch-Osmolovskaya's lab at the Winogradsky Institute of Microbiology, where they used a technique I'd never heard of called Denaturing Gradient Gel Electrophoresis and a myriad of selective media cultures to coax this organism out of the woodwork. Pretty hard-core, if you ask me.

Sergey Gavrilov : Electrochemical potential and microbial community composition of bioelectrochemical systems employed in situ in hotsprings of Uzon Caldera

This is a pretty awesome idea. Microbial fuel cells exploit the fact that cellular metabolism requires the transport of electrons outside the cell to deposit on acceptor substances, and couple this process to an electrical circuit. Sergey discussed a modification of this idea called sediment microbial fuel cell; instead of growing his microbes in the lab, he carried his cathode and anode out into the field and stuck them into a sedimentary formation in the environment.

The awesome part of this study is that Sergey isn't just looking for high power output. He's using the fuel cell to select for current-producing organisms from a diverse community, and then studying those organisms. After letting his circuits run for ten days, he found biofilms growing on the electrodes that had very different community structure from the controls (same setup, but with an open circuit). It's basically an enrichment culture that enriches for microbes that like to make electricity.

David Bernick : New discoveries in the hyperthermophilic genus Pyrobaculum enabled by deep RNA and genome sequencing

It's interesting to see how much fine structure can be found when an organism is sequenced deeply enough to capture it. David's team is using massive Illumina sequencing to do something like the Hubble Deep Field for an archaeal genome and its small RNA. They also sequenced a new member of the genus, P. oguniense, and discovered therein a new virus and a number of cool virus-related genomic features in the host.

Frank Robb : Lessons learned from sequencing carboxydotrophic bacteria and the race to discover hyperthermophilic cellulases

Frank was the only person at the workshop to give two talks, and they were both pretty cool. The first talk summarized results presented in a paper amusingly titled ‘That which does not kill us only makes us stronger’: the role of carbon monoxide in thermophilic microbial consortia. This work covered a lot of ground, including some compelling evidence for archaea-to-bacteria lateral gene transfer of chaparonins, as well as a results showing rapid accumulation of frameshift mutations when C. hydrogenoformans is grown under syngas, allowing it to grow rapidly by fixing carbon monoxide from syngas. Syngas is also known as wood gas, a simple intermediate for converting a variety of biomass feedstocks into usable fuel. If one wanted to obtain pure hydrogen gas from syngas, an organism that can eat the carbon monoxide could be handy.

The second talk presented some really interesting work in which a consortium of one cultured and two novel archaea was isolated from a thermal spring in Nevada that was able to grow on filter paper at 90C. A cellulase capable of degrading crystalline cellulose into reducing sugars at 100C was isolated, and the genes responsible were cloned and expressed in E. coli.

This is also pretty exciting for the biofuels people. One of the problems with moderate-temperature cellulases is that it's impossible to keep a huge vat of wet, ground up plants sterile. As soon as cellulase activity starts putting simple sugars into solution, something will start to eat the sugars. However, if you conduct the process at pasteurization temperatures, then you just have to worry about contamination by hyperthermophiles. So, as long as you keep people like Frank Robb and Karl Stetter from dropping their used lab equipment into your processing vat, you should get a nice yield of sugars from the cellulose without having it all eaten up by pesky yeasts and suchlike.

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