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Week 4/2009: A Fungus that Produces Pulp

Urban residents facing urban problems

Will the paper mill of the future smell like mushrooms in a forest in the autumn?  Microbiologist Taina Lundell, a university lecturer and Academy Research Fellow, dreams of a time when instead of high temperatures and strong alkalis, digesters will contain polypores or their enzymes.

The work-intensive phase of paper manufacturing detaches the light-coloured pulp fibres from the brown and glue like lignin, which is the binding agent in wood. Lundell says that many forest white-rot fungi, such as wrinkled crust (Phlebia radiata), Dichomitus squalens and Physisporinus rivulosus break down wood lignin, leaving only cellulose.

"If long processing times were allowed in the industry, the technology would work already," Lundell says. When wood is chopped into little pieces, and water, residual liquor from the food industry or some other inexpensive food for the fungi is added, the process works at room temperature. The problem is the slow speed, which does not fit quarterly financial accounting.

The utilisation of white-rot fungi has been studied for thirty years, but the technology has not yet been widely applied in the paper mill process as a whole. In experimental processes, they have been used in two work phases. In the preprocessing of fibre, they soften the wood before it is ground mechanically into a mass and, in addition, the rotting agents clean residual liquor containing lignin. In another part of the mill – where the biobleaching of paper is carried out – mould fungus enzymes are hard at work.

Lundell carries out genetic and enzymological basic research and studies how a compound like lignin can be broken down or converted using oxidizing enzymes produced by polypores.
In addition to manufacturing A4s, fungus technology is also applied to clean contaminated quantities of earth. Among environmental toxins, fungus treatment gets rid of carcinogenic PAH compounds.

The fungus is multitalented and consumes little electricity – it sounds like the perfect tireless factory worker of the future! It's yet another case of industrial labour recruited from the peaceful countryside.

"The most useful white-rot fungi we have isolated are rare fungi that are found in a state of nature in old forests. It is important for industry and the biotechnology of the future that people understand that these species must be conserved. Biodiversity is also economically profitable," says Taina Lundell. Lundell works at the Department of Applied Chemistry and Microbiology in Viikki.

The future of fungi in paper mills is studied by Professor Annele Hatakka's group. For more information on the group's projects and cooperation with industry: biocenter.helsinki.fi/groups.

Text: Kimmo Luukkonen
Picture: Wikipedia
Translation: AAC Noodi
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