Chemistry World Podcast - December 2008
00:10 -- Introduction
02:18 -- Forest fungus makes diesel direct from cellulose
05:12 -- Schemes to trap carbon dioxide in rock
08:04 -- Al Darzins describes the potential biofuel bonanza that is quick-growing microalgae
14:40-- Molecules weighed on a set of nanotube scales
17:54 -- Is plastic labware wrecking your reactions?
20:17 -- John Piggott reveals the chemistry of whisky flavour - and the best way to drink it
26:01-- How nature chaperones promiscuous proteins to ensure they partner with the right metal cofactor
29:36-- Caterpillars battle attacking ants with surfactant spit
32:18 -- The whisky-related Christmas chemical conundrum
(Promo)
Brought to you by the Royal Society of Chemistry, this is the Chemistry World Podcast.
(End Promo)
(00:10 -- Introduction)
Interviewer - Chris Smith
Hello! Welcome to the December edition of the Chemistry World Podcast with Victoria Gill, Richard Van Noorden and Matt Wilkinson. I'm Chris Smith. Coming up, the newly discovered fungus that naturally makes diesel and it could rewrite what the text books tell us about where oil came from.
Interviewee - Victoria Gill
The discovery of this particular fungus could actually challenge the theory of how hydrocarbon fuels formed in the earth. So obviously, fossil fuels are thought to have formed over millions of years from dead vegetation, but it could be that fungi or organisms like this one could actually have digested vegetation and produced hydrocarbons a lot more quickly, so we could have younger fossil fuels forming naturally.
Interviewer - Chris Smith
Victoria Gill, who will be unveiling the story of myco-diesel very shortly and on the subject of oils, what crop yields the most? The answer might shock you.
Interviewee - Al Darzins
The reason that people are very interested in algae these days is that microalgae, these microscopic photosynthetic micro organisms produce more of oils or lipids per acre than most other terrestrial plants. Soy beans produce about 50 gallons per acre, algae with the current state of the technology, we think can may be produce about 1200 gallons per acre per year.
Interviewer - Chris Smith
That's what some people are saying that algae are the biofuels of the future. And is this the world's smallest pair of scales.
Interviewee - Richard Van Noorden
Well some Spanish researchers this month from the United Science Research Center in Barcelona gave us yet another example of these amazing ultra sensitive carbon nanotubes that can weigh molecules to a resolution of within 3 gold atoms.
Interviewer - Chris Smith
Sterling stuff and also on the way of course is the answer to last month's Chemical Conundrum.
Interviewee - Victoria Gill
What is the chemical in wintergreen mints, the US version of Polo Mints for our UK listeners that creates a faint green fluorescent glow as you chew them.
Interviewer - Chris Smith
So if you have sent in a suggestion, you could be one of this month's winners. The answer is on the way.
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(02:18 -- Forest fungus makes diesel direct from cellulose)
Interviewer - Chris Smith
You've heard the phrase fruits of the forest, but this discovery Victoria, really is extraordinary, because scientists have uncovered a fungal fruit of the forest that makes diesel.
Interviewee - Victoria Gill
Indeed, this is fruits of the Patagonian rain forest and so Gary Strobel and his team from Montana State University have found a fungus that converts cellulose directly into diesel or diesel-like compound and cellulose is the most abundant organic molecule on earth. So this could be potentially, I mean, big news for biofuel production.
Interviewer - Chris Smith
Why would a fungus want to make diesel anyway?
Interviewee - Victoria Gill
To feed itself. Cellulose is particularly abundant in plant material, so a fungus that lives in the rain forest would want to breakdown cellulose into food constituents for itself and this fungus just so happens to break that cellulose down directly into a mixture of hydrocarbons that is a fuel and they have named it myco-diesel, but it is essentially biodiesel.
Interviewer - Chris Smith
And presumably you would have some kind of reaction vessel where you would have this fungus growing and feed cellulose and which turn out diesel and related products.
Interviewee - Victoria Gill
That's not a very practical solution having a fungus. It's a rather large vessel for the molecule machinery that actually churns out this mixture of hydrocarbons that you want. So the real key to applying this research is to get the genes, the molecular machinery that do the work that you want and transfer them into another host, a smaller host say a bacterium, you could then upscale that in some sort of a reaction vessel and make biodiesel directly.
Interviewer - Chris Smith
Is it a complicated biosynthetic pathway that involves lots of steps or is it just a few genes and therefore pretty easy to get bacteria to do for them?
Interviewee - Victoria Gill
They don't quite know yet and in fact, there is a bit of a family link in here. Apparently, Gary Strobel's son who is chair of molecular biophysics and biochemistry at Yale is actually working on isolating the series of genes that carry out this process. So they are going to try and take those genes out and do exactly that; find out what they are and isolate them and put them into a different vehicle.
Interviewer - Chris Smith
Have they actually got any success stories yet in terms of just feeding this fungus various types of biomass to see what it can work on or is it just going to be wood chips and that's it?
Interviewee - Victoria Gill
Apart from the fact that they have fed this fungus in the lab on an agar plate and it makes this mixture of hydrocarbons which is great news. No they have not taken that any further than that. But the interesting postscript of this research is that the discovery of this particular fungus could actually challenge the theory of how hydrocarbon fuels formed in the earth. So obviously fossil fuels are thought to have formed over millions of years from dead vegetation, but it could be the fungi or micro organisms like this one could actually have digested vegetation and produced hydrocarbons a lot more quickly, so we could have younger fossil fuels now forming naturally.
Interviewer - Chris Smith
Fascinating and I wonder if we will actually get to the bottom of that one. Thanks Vic.
(05:12 -- Schemes to trap carbon dioxide in rock)
Interviewer - Chris Smith
And once you've made your biodiesel and burned it, it might make a lot of CO2 and it has got another problem on your hand which is the accelerating greenhouse effect and Matt you may have a solution though.
Interviewee - Matt Wilkinson
Yes indeed, well, it's not me that's got a solution, but it could well be Peter Kelemen of Columbia University in the US, who has used a clever carbon dating technique, the same sort of technique that is used to date mummies and various other artefacts, to study how quickly certain types of rock absorb carbon dioxide and they found that a certain type of rock can absorb CO2 much quicker than ever previously thought.
Interviewer - Chris Smith
Where is this mineral and how do you think it could be used for things like carbon sequestration then?
Interviewee - Matt Wilkinson
Well the mineral is found in various places around the world, mostly underground and it has to be said there's a whole bed of this rock that's actually exposed to the atmosphere in Oman where the research was done. Based on these calculations, Kelemen believes that this rock could absorb up to 4 billion tons of CO2 per cubic kilometre.
Interviewer - Chris Smith
That's a lot. Isn't it, so how does that relate to how much CO2 we produce in a year?
Interviewee - Matt Wilkinson
We currently produce about 30 billion tons of CO2 a year. So it's a sizable chunk.
Interviewer - Chris Smith
It's a realistic ball park to think this could be a strategy, how does he propose that we could exploit this mineral to lock away CO2 then?
Interviewee - Matt Wilkinson
Well, this is where it will get a little bit speculative and somewhat more interesting. He has two approaches that might be used and we also may be need to put this into perspective that currently most people that are thinking about doing this and there's lots of companies involved in trying to do carbon dioxide sequestration and have actually tried to mine the rocks and get them out of the ground and then do this kind of reaction out of the power plant. Kelemen believes that what you could actually do is pump the CO2 to the rocks even if they are underground.
Interviewer - Chris Smith
Does this mean that then you have got to get all the CO2 out of the waste gases of power plants and then get that to the minerals in order to absorb it because that sounds terrifically energy hungry and resource hungry?
Interviewee - Matt Wilkinson
That was his first suggestion, however, he has come up with an even clever idea, they won't be quite as effective because this reaction actually produces heat really once that happened and by increasing the heat of the rock, the actual rate of absorption increases as well. So by pumping in water that's absorbed CO2 from the air down into deep beds of this rock that hopefully in the mantle that are relatively warm already, you could actually imagine pumping CO2-ladden water that just absorbs CO2 from the air straight into the rock and letting the reaction go as is.
Interviewer - Chris Smith
What is actually the chemical reaction that is taking place and that's locking away the CO2 and what is the end result?
Interviewee - Matt Wilkinson
It is not exactly a clear cut single reaction, what's happening is that a series of silicate rocks that make up the peridotite are actually being converted into a series of different carbonate rocks.
Interviewer - Chris Smith
So a rock solid way to combat climate change, you could say. Thank you Matt.
(08:04 -- Al Darzins describes the potential biofuel bonanza that is quick-growing microalgae)
Interviewer - Chris Smith
Another way to cut down greenhouse gas emissions is to better exploit the chemistry of the natural world and a surprising new kid on the biological block that can help us to do this is algae and to find out how Meera Senthiligam spoke to Al-Darzins.
Interviewee - Al Darzins
The reason that people are very interested in algae these days is that microalgae, these microscopic photosynthetic micro organisms which should not be confused with macro algae which are like the seaweeds, may have the potential of producing very high lipid or oil contents potentially up to, you know, may be 60% of their dry cell weight. They also have very rapid growth rates, may be one doubling per day. They also can produce more lipids or again oil, I use that synonymously oils or lipids per acre than most other terrestrial plants, for example a crop that we grow quite a bit of here in the United States the soy beans which produced about 50 gallons per acre. Algae with the current state of the technology we think can may be produce about 1200 gallons per acre per year with a potential of may be in the future producing as much as 5 to 6000 gallons per acre per year. So you can see that as 100 times more than soy beans.
Interviewer - Meera Senthilingam
Well a fact to making this a particularly green technology over other biofuels out there is the fact that the algae can apparently be fed on the waste carbon dioxide from current power plants. Is this really possible?
Interviewee - Al Darzins
Yes, that is absolutely true. In fact these algae need very few nutrients. So they need obviously CO2, they need some nutrients like nitrogen and phosphorous and then of course sunlight. So they have the capacity of using the CO2 that is perhaps present in flue gases in either a coal-fired or natural gas-fired power plants and so they can take quite a bit of that CO2 out of the flue gases and use it for their own growth.
Interviewer - Meera Senthilingam
But how realistic will it be to incorporate this into existing power plants?
Interviewee - Al Darzins
I mean it has already been shown that organisms can actually grow with flue gases and what I point to is an example is a colleague of mine in Israel Ami Ben-Amotz is currently working with a company called Seambiotic and they have raised growth ponds associated with the Israeli electric company. So basically they take their flue gas and they use the CO2 bubbled through their ponds and actually grow algae all year long. So in fact to some degree it has already been done.
Interviewer - Meera Senthilingam
But can the algae actually be grown sustainably?
Interviewee - Al Darzins
Well, the main issue, in order to have it grown sustainably is access, first of all, to large amounts of water, the likelihood is that you're not going to use fresh water in the future, you're probably going to use something like the saline or brackish water, may be ocean water, depends on what the availability is. You're also going o be growing this on non-arable land and so again I make the point in the united States, there are large tracks in the deserts southwest, Arizona, New Mexico, Texas may be around the Gulf Coast as well, where you know, they don't grow perhaps, you know, a lot of corn and soy bean and those sorts of things in these areas because of the large amount of sunlight that they get could be excellent places to grow algae.
Interviewer - Meera Senthilingam
But the problem with previous biofuels is that they've not been very cost-effective, is algae going to be cost-effective?
Interviewee - Al Darzins
Not yet, we can grow algae large scale, we can harvest the algae, we can extract the oil out of the algae, we can even convert the oil into a very decent diesel-fuel or a green gasoline or perhaps even a jet fuel, can we do this all integrated into one component cost-effectively yet, no we can't.
Interviewer - Meera Senthilingam
So, is this the main challenge to be overcome, or are there other challenges involved as well?
Interviewee - Al Darzins
No there is actually quite a number of challenges in each one of the areas that I talked about. So for instance, there is still a huge debate over which cultivation system is actually the best to use. There are some people who think that these large open race-way ponds are the way to go, may be they're the cheapest. There are other people who are actually promoting these closed photo bioreactors, these tend to be a little bit more expensive, so there's still a huge debate on which way to grow these algae. Two other areas are, how do you remove all the water from the algae? They'll contain in concentrations of may be a few grams per litre of water. You have to remove all that water, harvest the algae before you can actually extract the oil and then we really don't have cost-effective ways of extraction of those oils at this point in time, so there are many areas, both on the biology and on the engineering side that we still have to figure out and make I much more cost-effective.
Interviewer - Meera Senthilingam
So it sounds like there are still a lot to be done. When are we likely to see this actually entering the fuel market?
Interviewee - Al Darzins
That's a very good question. You know, there are some companies, who are growing their algae in a very unique way, not photosynthetically, not with sunlight or CO2, but actually in the dark, with sugars and this one company, Solazyme, has probably been the only company today that has made any significant amount of oil that people can now start looking at, at making at least evaluating the conversion to oil, but that's certainly not on the commercial scale yet. It has been our estimation that it still may be about 5 to 7 years, before we see you know, commercial production of these oils, may be full-scale, full-commercial production will have to wait till about 10 years.
Interviewer - Meera Senthilingam
That's quite a wait. So, when it does come into action, what sort of yield will it produce?
Interviewee - Al Darzins
In the future, we think that there's going to be a very interesting mix of a variety of different fuels. I don't think there's going to be one clear winner. I think that algal oils converted to a variety of biofuels will be one, but you know, if we can devote large amounts of land to growing these algae, it's not inconceivable that we could may be displace 10 to 20% of our petroleum, diesel usage.
Interviewer - Chris Smith
Al Darzins talking to Meera Senthilingam. He is a group manager at the US's Renewable Energy Lab.
(Music)
Interviewer - Chris Smith
This is Chemistry World with me Chris Smith and soon to come, how science is hoping to make better whiskey in Scotland and how caterpillars are using chemical warfare to fend off ant attacks.
(14:40-- Molecules weighed on a set of nanotube scales)
Interviewer - Chris Smith
But first, Richards, the world of weighing has taken a big step forward on the nanoscale problem, talk to us about this.
Interviewee - Richard Van Noorden
Well, some Spanish researchers this month from the Nanoscience Research Center in Barcelona, gave us yet another example of these amazing ultra-sensitive carbon nanotubes that can weigh molecules to miniscule resolutions. So these guys led by Adrian Bachtold created a device that could weigh proteins to a resolution of within three gold atoms.
Interviewer - Chris Smith
How does it work?
Interviewee - Richard Van Noorden
Well, this protein weighing machine is a nanotube and its pinned between two electrodes and a vacuum and the nanotube is a resonator that vibrates like a guitar string to frequency and when an atom hits it, it changes it's frequency of vibration and by relating that to mass you can weigh very tiny particles. Now the question is, is this ever going to replace a mass spectrometer, which is the usual way we use to measure mass by fragmenting molecules up and sending them flying through a tube and bouncing electric and magnetic fields to work out how heavy they are, and the exciting thing is these guys say in the future these tiny nanotubes will improve on mass spectrometers. They are not quite there yet, so we decided to ask them and other groups how this might work. What they say is, it could be possible to make devices that could discriminate between isotopes of the same element, could follow reactions of single protein. So you could put haemoglobin on molecule on a nanotube and look over time how it, say, releases oxygen atoms as it reacts, which is pretty incredible. Now mass spectrometer, at the moment, they can get down to the resolution of a hydrogen atom. But as molecules get bigger and bigger, when you talk about the size of proteins, they just don't have that resolution. So, really these nanotubes are offering something that mass spectrometers can't give you.
Interviewer - Chris Smith
Now, the principle ways reasonably straightforward. You vibrate something and when you add weight to it, the vibration changes, but how do you actually measure the vibration in the first place. How are they doing that?
Interviewee - Richard Van Noorden
What is often done optically, you can do with a laser beam and you shine the laser beam and you can see how that change as it comes out and you can relate that to vibration and that's normally the way it's done. In fact, one team, California-Berkeley team led by Kenneth Jensen they've made a vibrating cantilever that can get down to a 2/5th's of a gold atom and this also works at room temperature, so we're talking tiny resolutions there.
Interviewer - Chris Smith
If we can already do this with a mass spectrometer, why do we want to do with anything different?
Interviewee - Richard Van Noorden
Well, the advantages nanotubes might offer are first, sensitivity, mass spectrometers are very sensitive, but as you get to really large molecules, that little difference in an oxygen atom being lost, it gets hard to detect. Secondly, we've got the size and the weight. The nanotube is very light; an array of them would still be miniscule, very light should be easy to carry around, when put in a device. and though mass spectrometers are getting hand-held, they're not going to be able to compete with that and the really exciting thing about being able to determine between different isotopes, determine how proteins are reacting, follow chemical reactions just by real-time mass detection, as molecules land on nanotubes that are around, that's pretty exciting and that's where this research is headed.
Interviewer - Chris Smith
It's exciting and we can see all kinds of potential for that if we are cantering them down because of course it makes them very portable and then you can do things up like bio-detection and other things like environmental monitoring. Thanks Richard.
(17:54 -- Is plastic labware wrecking your reactions?)
Interviewer - Chris Smith
Now to a way in which our experiments could be thrown into disarray, Matt tell us about this.
Interviewee - Matt Wilkinson
Yes, a team of Canadian researchers led by Andrew Holt at the University of Alberta have shown how chemicals leaching from plasticware can actually affect the reactions that you do in them dramatically.
Interviewer - Chris Smith
So what were they doing? How did they find it?
Interviewee - Matt Wilkinson
Well, they were initially studying how an enzyme linked to Parkinson's disease, reacted with ammonium chloride, and surprisingly they found that it didn't seem to matter, how much they diluted that ammonium chloride, the effects were still there.
Interviewer - Chris Smith
So something was amiss. How did they try to find out what it really was?
Interviewee - Matt Wilkinson
What they did was that they started off by seeing if they could extract anything from the containers themselves and they found that there were two chemicals in particular that came out of the polypropylene containers, while they were doing these reactions that seemed to inhibit the enzyme. One of these is the disinfectant DiHEMDA, which is used to stop anything growing in the containers, while they're in storage and the other is the lubricant, oleamide, that's used to stop the packages from sticking together during the manufacturing process.
Interviewer - Chris Smith
So where were these chemicals coming from? Were they actually in the plastic itself?
Interviewee - Matt Wilkinson
They're actually in the plastic themselves.
Interviewer - Chris Smith
And do we know how they were interfering with the chemical reaction that the researchers were trying to investigate?
Interviewee - Matt Wilkinson
They've actually found that both of these chemicals are inhibitors of the enzyme itself.
Interviewer - Chris Smith
And this is obviously a bit of a canary in the cages, saying there are things in these plastic containers that could affect other reactions. Do they speculate as to how well this could throw a spanner in your scientific works?
Interviewee - Matt Wilkinson
Well, yes it kind of throws a spanner into any reaction that you're doing, that's incredibly sensitive. If you're using any kind of plasticware from a container, through to a pipette, any plastic has the potential to leach some of its constituent chemicals out of it, the most interesting thing, I think, about this of course is that people have started using disposable plasticware to avoid the problems of incomplete cleaning of glassware.
Interviewer - Chris Smith
So, is this the death knell for laboratory plasticware then?
Interviewee - Matt Wilkinson
No, absolutely not, I think that it really emphasizes the need to run controlled experiments as we all should do anyway and you need to seriously control the plasticware that you do use, so that you can actually make sure that conditions are kept exactly the same.
Interviewer - Chris Smith
So may be it's not always true the bad workman blame their tools. Thank you for that Matt.
(20:17 -- John Piggott reveals the chemistry of whisky flavour - and the best way to drink it)
Interviewer - Chris Smith
And now to a big question that whiskey drinkers are grappling with everywhere; should you add water or swallow the stuff neat? John Piggott
Interviewee - John Piggott
It all depends on your personal preference really that some whiskeys can be very nice, if they're drunk straight from the bottle strength or even sometimes at barrel strength, but they need to be generally very well matured, very old whiskeys, if you take cognacs for example, at bottle strength. But for general drinking then, you probably better to take a cheaper whiskey with some water in it that could be the process of adding the water then obviously dilutes the alcohol and so it changes the relative concentrations of the flavour compounds in the headspace and so it changes the sensation you get.
Interviewer - Chris Smith
What are the main flavours or determinants of the taste experienced when you do drink a fine whiskey?
Interviewee - John Piggott
It's very difficult to say because there are so many volatile flavour compounds in whiskey. Hundreds may be over a thousand in some products. The major compounds that develop as the whiskey is matured, derived from the wood so that you get a mixture of a compound from the fermentation from the original material, the malt from the changes during the distillation and the wood materials, then add another layer on top of that so you get a very complex mixture.
Interviewer - Chris Smith
And when you take the whiskey into your mouth, what actually happens to those compounds?
Interviewee - John Piggott
When you taste a whiskey, then obviously it warms up in the mouth, is a diluted a little bit by the saliva, which will be inevitably be present, and so the volatility of some of the flavour compounds changes, so if it is, as its diluted, then some of the compounds, more soluble in alcohol will tend to be released, the compounds more soluble in water will tend to stay in the solution, so that the amount of water present, the amount of saliva changes the relative volatility of the flavour compounds. But if it's a well matured whiskey, then it seems from some of our results that it's more stable than the dilution of the drinking, the change in temperature doesn't seem to have as much effect.
Interviewer - Chris Smith
It sounds like you do a fascinating work, which is terribly fun, at the same time, or do you not get actually to actually drink the whiskey yourself?
Interviewee - John Piggott
Well, when we're doing the experiments in the lab, then most of the time, its' nosing only. So we do have a whiskey tasting machine which will do some of the work for us, but I certainly enjoy a drink when I am not at work.
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