Three-dimensional visualisation of bacterial decay in individual tracheids of Pinus sylvestris

Archaeological wood from waterlogged environments is mainly degraded by erosion bacteria. Under the light microscope, a distinct chequered decay pattern is often found in superficially to moderately degraded wood. Serial sections of Pinus sylvestris, degraded by erosion bacteria, were examined to gain an understanding of this phenomenon. An advanced image analysis program was used to transform series of 2-dimensional (2-D) images from attacked fibres into 3-D illustrations in order to visualise variations in decay along 340 mum of the tracheid. Degradation by erosion bacteria proceeded from the cell lumen into the secondary cell wall. Attack was initiated at several positions in the same tracheid. The chequered pattern observed in transverse sections, often referred to as degraded fibres adjacent to sound ones, shows only the decay status at the section point. A sound cell wall does not necessarily indicate a sound fibre. A fibre in moderately degraded wood often consists of both degraded and sound areas.