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Tunnelling Bacteria: An Underestimated Threat to Wooden Structures

Tunnelling bacteria caused the premature failure of pine posts in a kiwi fruit orchard even though the posts had been pretreated with  a highly toxic wood preservative used to protect them against wood-degrading fungi.

Tunnelling bacteria caused the premature failure of pine posts in a kiwi fruit orchard even though the posts had been pretreated with a highly toxic wood preservative used to protect them against wood-degrading fungi.

By Adya Singh & Thomas Nilsson

Bacteria that have evolved a clever way to feed by tunnelling within cell walls can thrive in pretreated wood in humid conditions, and may even have damaged new houses in Auckland.

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Our common perception of bacteria is that they are simple organisms capable of performing only small tasks for their survival and well-being. However, it is beginning to emerge that bacteria have evolved more sophisticated strategies and can ingeniously interact with their living hosts and effectively talk to their own kind within colonies.

This sophistication also extends to nutrition, with the discovery that some bacteria have evolved an ingenious way of obtaining nutrients from wood. By tunnelling within the cell walls of wood, these bacteria are also sheltered from predatory amoebae and nematodes.

We made this discovery while investigating the premature failure of radiata pine posts in a kiwi fruit orchard even though the posts had been pretreated with copper–chrome–arsenate, a highly toxic wood preservative used to protect them against wood-degrading fungi. We found that an unusual type of microbial activity was the main reason for the decay of the posts. The decay pattern was different from what is typically caused by fungi.

A detailed examination combining light microscopy with high resolution transmission electron microscopy showed that the unusual form of decay was produced by bacteria that had penetrated into the cell walls of the wood, producing spectacular features that had the appearance of a branched network of tunnels containing...

The full text of this article can be purchased from Informit.