Scientists discover fungus to convert biomass into ethanol, and into biodegradable antibacterial and super-absorbent material

A research team at University College of Borås in Sweden, headed by Professor Mohammad Taherzadeh, in collaboration with scientists from Göteborg University has made a unique discovery. It consists of a fungus that converts biomass waste into ethanol in a highly efficient manner. Moreover, from the residual biomass resulting from the ethanol production the researchers were able to extract a powerful antibacterial and super-absorbent material that can be used in the hygiene industry (medical and sanitary napkins, etc...). The material is biodegradable, and promises to solve a significant waste problem.

Seven years ago Mohammad Taherzadeh and his team started their search for a fungus for ethanol production. They found a group of filament-producing fungi, so-called zygomycetes, that have proven to have interesting properties.

"Today baker's yeast is used for the production of ethanol, but we have found a fungus that is more effective than baker's yeast," says Mohammad Taherzadeh, professor of biotechnology at the School of Engineering, University College of Borås, and one of the world's leading ethanol researchers.

Within the order zygomycetes, more than 100 different fungi were tested, and in the end, the one with the best properties was singled out. The fungus, which is a saprophyte, is extremely easy to grow in waste and drainage.

"It is low maintenance, requiring hardly anything to start growing and degrading the waste. The temperature plays some role. We have tried to get it to grow in sulfite lye, but also in brush, forestry waste, and fruit rinds, and the results were equally good in all cases," reports Mohammad Taherzadeh.

Converts waste to raw material
Being able to convert sulfite lye for the production of ethanol is good news, in both economic and environmental terms. Sulfite lye, which is a byproduct of the production of paper and viscose pulp, is difficult for factories to dispose of since it contains chemicals that must not be casually released in nature. From being a highly undesirable byproduct for the paper industry, sulfite lye will now be an attractive raw material for the extraction of ethanol:
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"This is truly exciting. Zygomycetes in ethanol production represent an unknown area. We are the only scientists in the world to have presented them as ethanol-producing fungi, but we realize that the potential is huge," says Mohammad Taherzadeh, who relates a curious anecdote that the fungi have another use in Indonesia: they are a food fungus.

Super-absorbent bonus effect
Zygomycetes are not only highly effective in producing ethanol; the research team also found that the biomass that is left over in the production of ethanol can be used to extract a cell-wall material that is super-absorbent and antibacterial. What's more, it's a biological material that can be composted and recycled:

This discovery opens an entirely new dimension for research on the fungi, according to Mohammad Taherzadeh, whose project "Production of antimicrobial super-absorbent from sulfite lye using zygomycetes" was recently awarded more than 800,000 Swedish Crowns (€85,000/US$ 114,000) from the Knowledge Foundation to continue its research into this cell-wall material.

Reduces greenhouse effect
Super-absorbent material is used in diapers and feminine hygiene products, but also for bandages and other products for treating wounds. Today the super-absorbent in these types of products is polyacrylate, but polyacrylate is not biodegradable: it has to be burned. This combustion release carbon dioxide in the air, a compound that aggravates the greenhouse effect. On the other hand, if polyacrylate is replaced with this biological super-absorbent, diapers will not have to be incinerated, but instead can be composted, retted, and converted to biogas. This, in turn, entails a reduction in the emission of carbon dioxide into the air.

Kills bacteria and fungi
The antibacterial property of the biological super-absorbent is also advantageous in comparison with polyacrylate.

"Our cell-wall material absorbs about ten times its weight in liquid. It can also kill bacteria and fungi, which means that a diaper would not irritate the skin and would last longer before any unpleasant odors arise. We have experimented with adding e-coli bacteria as well, an aggressive sort of bacteria, and the cell-wall material manages to neutralize them," says Mohammad Taherzadeh. Equally good results are reported from experiments with other bacteria types, such as Klebsiella pneumonia and Staphylococcus aureus, as well as the fungus Candida albicans.

"The research will continue on ethanol production as well, but our focus is now on developing the cell-wall material further. Since this is an unknown field, a great deal of work will be needed for us to fully understand the potential of this material," says Mohammad Taherzadeh.

In stores soon?
This research is also tied to product development work, being carried out in close collaboration with Rexcell AB (formerly Duni) and Medical Equipment Development AB. "Together with these two companies we are trying to add this cell-wall material to paper in a process called 'airlaid non-woven'." The aim is to develop a commercial product that can be used in many industries, according to Mohammad Taherzadeh. "Our experiments have been promising thus far, and our collaborative partners are looking into the possibility of patenting the method."

More information:
European Research Headlines: Researchers discover link between fungus and ethanol - March 30, 2007.