Science Interviews


Sun, 15th Jan 2006

How Algae Get Their Vitamins

Dr Alison Smith, Department of Plant Sciences, University of Cambridge

Part of the show Plant Science, Composting and Mosquito Repellents

Chris - Tell us about your algae.

Alison - My algae constitute the largest group of organisms that fix carbon dioxide from the atmosphere, which means they take the carbon dioxide and turn it into sugars. They use the energy of the sun to do that. Algae are responsible for about 505 of the world's carbon dioxide fixation, so they're very important in terms of global carbon cycles. What we've been interested in is the fact that algae aren't completely able to live on their own. This is because they require a source of vitamins. In that respect, they are quite like animals. There is one vitamin, vitamin B12, that plants on the land can't make . So if you're a very strict vegetarian, you won't get it from your food unless you don't wash your vegetables very well.

Chris - So what do algae do?

Alison - These algae appear to take it up from their environment, but they can't get it from sea water because the levels of vitamin B12 in the sea water are just to low to support their growth. Instead what they appear to do is get it from bacteria.

Chris - So these algae have bacterial clusters hanging around with them that are feeding them vitamin B12?

Alison - Well it appears to be like that. It's hard to show it happening in the seas, but what you can do in the laboratory is grow the algae in a flask. You can then see that around the outside of the algae there's a glue-like mucilage and the bacteria stick to that.

Chris - So in return for giving the algae B12, do the bacteria get some protection then?

Alison - It's not so much protection as they actually get some of the sugars that the algae make.

Chris - So it's a symbiotic relationship.

Alison - Exactly.

Chris - Now, I want you just to comment briefly on this recent methane story. Frank Keppler from the Max Planck Institute said that they were just messing around in the lab and found that plants produce large amounts of methane. They don't know why they do it, and even the leaves they drop my produce bits and pieces of methane. But why should they do that and what do you think the implications are? What will this be doing to plant scientists around the world now?

Alison - I think it's something that's completely unexpected, like you say. It really does require a considerable effort on behalf of plant scientists to work out why plants are doing this, what the benefit is and what's the chemistry behind it. These are all very interesting questions. In fact plants give out all sorts of volatiles and I think John knows about one of these.

John - Yes. Methane is potentially very useful but it's not valuable enough to capture from plants. We're working on an idea at the moment to try and capture isoprene, which is a really very valuable chemical. It's the type of chemical you can make rubber out of, and if we can capture that from plants we'd stop it becoming a greenhouse gas problem and get something really very useful for industry.


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