ON ATTACK OF CONIFEROUS WOOD BY BACTERIA

In order to investigate the possible damage to water-stored softwood and to determine the microflora present, debarked spruce and Scots pine specimens were stored under water for 22 months and periodically examined. The wood was attacked by many types of bacteria, which can be divided into four groups: coliform bacteria, other sporeless bacteria, aerobic and anaerobic spore producers. The isolated cultures were tested for enzyme production on various sugars, alcools and polysaccharides. Some bacteria exhibit pectolytic activity and are able to degrade pectic substances in the pit membranes. Bacillus omelianshii proved to be the most important bacterium for which the cellulolytic activity was demonstrated on various substrates. In no case an attack of the lignified tracheid walls occured, and the degradation of pit membranes was always confined to the sapwood. Wood attacked by bacteria becomes more permeable to liquids, and preservatives therefore may be more readily introduced. A reduction in wood strength is generally not a cause for concern, since the attack takes place very slowly. The importance of bacteria in simultaneous or successive attack by wood-destroying fungi and in the detoxification of preservatives has still to be investigated. © 1968 Springer-Verlag.