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Interview: Michael Sulu, biotechnologist

Dr Michael Sulu is a research fellow in biochemical engineering, with interests that involve the production of biofuels, the biorefinery concept and the production of energy from waste sources. 

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What place does sugar have in your world?

Sugar is a food source for the microorganisms we work with; they metabolise, or ferment it. These organisms are very important industrially and are used to make lots of different types of food, energy and pharmaceutical products.

We usually use D-Glucose which is the least hydrated form of powdered dextrose - it's very fine. Every single process we do uses sugars as the carbon source for microbes to produce other materials. But we have lots of different forms of sugar and sugar alcohols in our labs for different purposes.

We demonstrate these transformational processes with students by making beer. A complex variety of sugars are produced during the malting process which is when the warm wet grain germinates. Different grains will produce different sugars - maltose, glucose, hexose, pentose. We use the enzyme amylase for malting. This is an ancient way to get fermentable sugars from grain. Amylase is contained in saliva and there are various traditional fermented drinks which are kick-started by chewing the grains, like some Sakes in Japan and Chicha in South and Central America.

In the lab we can also make the sugars we need from other organic materials. We make mannitol from brown seaweeds - they have more carbohydrates than other seaweeds.

What is the most interesting thing that sugar does?

It's an energy source which microbes love, but at high concentrations it's anti-microbial.- An over-proliferation of microbes because of too much food means they can't convert the sugars so they make toxins and die. A tragic sugar love story. Too much sugar stores fats for us, and converts into acid for microbes.

Sugar also loves water - you can get 700grams into a litre before it's saturated.

Another interesting phenomena, is that our immune response is based on sugar coating patterns on our cells called glycosyl residues. When cells make chemicals, they add a sugar coating. These sugars have a signalling or recognition fingerprint effect with immune and other cells which is surprisingly important to the body and which we use a lot in our work. This is the basis of how vaccines work; you can present sugars in patterns to stimulate immune response, it's a mimicking thing. If an antibody you have made has the wrong sugar pattern on it, it won't work. These sugars have to be human-like so they don't get ignored by immune cells. If you were to disrupt your bodily ability to use sugar - you would die pretty quickly, and I'm not sure how you would die first - of immune system failure or brain starvation. So health-wise you run on sugar.

How does sugar relate to power?

Sugar can shape the economy. AB Sugar took over British Sugar and they now produce medical marijuana in huge quantities as kind of a by-product. They previously used the waste heat and C02 from sugar production for growing tomatoes and strawberries, but now it's all given over to marijuana as it makes more money. We can't use it in the UK but we can grow it.

Industrial sugar beet ecology produces lots of other products. Sugarbeet pulp residue is fermented into bioethanol, or made into platform chemicals for pharmaceuticals. Waste is money - there is 2kg of waste per tonne of industrial sugar produced. Most industrial processes have realised this and use or sell all waste products, as sugar itself is such a low-value product. It's possible that the government’s recent drive to reduce and tax sugar is tied up in the economy of sugar imports. I suspect that the health of the people is only a more palatable reason for change.

Sugar Beet Ecology Wissington Norfolk

British Sugar Wissington biorefinery (Norfolk, UK). Image shows the ecology of a sugar-beet processing plant.

In terms of literal power: fuel, sugar is pure energy. We can convert it to usable fuel easily via a couple of methods - liquid and gaseous. With liquids, you feed microbes sugars, and then stress them out so they make and store fats as lipids, which you can then convert into biodiesel. Or you make alcohols by microbial fermentation - creating ethanol or butanol by breaking down the sugars in to liquid fuel. The gaseous method is by reduction - removing oxygen and replacing it with hydrogen to make methane, or you can just use the extracted hydrogen. Hydrogen is the most environmentally friendly use of sugars as fuel. My PhD involved trying to find a bio method of making hydrogen without electrolysis, using waste sugar from the Cadburys factory. It's a honey-like substance but white; a waste product you can convert into different things.

How do you feel towards sugar?

I think it's a delicious poison. I give it up for lent every year - kind of a reset. It's amazing  how different foods taste when you cut it out. I always give up sugar, sometimes other things but sugar is the hardest as its hidden in everything. It's so connected to the rituals around it, like drug taking, it's an office faux pas to say no to cakes someone has brought in.

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Is it animal, vegetable or mineral?

It's not animal, but I guess we make it. It's vegetable derived, hmm. I wouldn't say mineral, although it's not alive it does have a life of its own. It's one of the base energy units - so integral to life.

Where does sugar happen?

Everywhere, it's so integral, it happens everywhere. The body makes sugars - some we get from what we eat but some we make. We might convert or break down other substances to get the chemical structure of sugars we need, it's a simple substance to construct.

Is there sugar in the air?

Yes! bacteria are in the air using sugar and covered in sugar.

Is there sugar in space?

If there is life in space then yes.