Friday, 13 July 2012

The Taming of Aspergillus

Many species of Aspergillus are potential pathogens to man & animals. Many more provoke allergic reactions and cause severe discomfort. How then was a species isolated 7-9000 years ago and has been in use ever since to help make food?

Aspergillus oryzae
 Aspergillus oryzae doesn't exist in the wild. It is an entirely domesticated little beast that has none of the dangerous habits of its close cousins - rather like our domesticated dogs and cats. An isolate of Aspergillus flavus was taken from the wild, probably chosen for its inability to produce mycotoxins, and was fed a rich diet of starch on which it has existed ever since.

Once a micro-organism starts to grow on a single food source it immediately starts to adapt so as to more efficiently use that food - it is driven to do so via natural selection as any strains that develop to grow faster or more efficiently will quickly overgrow less well developed strains.
Of course man has probably offered a helping hand along the way by actively choosing the best strains for his purposes. After 9000 years of this the only strain left is highly adapted to that one food source.

Scientists have now taken a close look at the genome of 'tame' A. oryzae in an attempt to discover how it differs from the wild species it is descended from (A. flavus) and what changes have happened to optimise its use of starch and how efficiently it produces sugars. This may well give us clues on how to best alter other similar fungi to perform better in other industrial processes.

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