Microbial Attack of CCA-Treated Pinus radiata Timber from a Retaining Wall

Abstract

Light and electron microscopic observations were made of Pinus radiata wood treated to a high retention of copper-chrome-arsenate (CCA), which had failed after approximately 11 years in Service. The predominant wood cell wall degradation patterns seen under the light microscope and scanning electron microscope äs channels and shallow depressions and which were probably responsible for failure of the pole were shown by transmission electron microscopy to be caused by erosion bacteria. Although this type of wood decay is known, the predominance of attack of deeper regions of the pole by erosion bacteria was unusual and significant in terms of the ecology of wood degradirig bacteria. Soft-rot was seen in outer regions of the wood at the groundline but was very rareiy seen in deeper regions. MicroscopyThe pole had dried out on arrival at the laboratory. Small Chips of wood, 5 mm thick in a radial direction were removed with a chisel at the surface, and at depths of 20, 40, 60 and 80mm, across the diameter of discs. Transverse, radial and.tangential sections were Holzforschung / Vol. 48 / 1994 / No. 6

Bacteria as Important Degraders in Waterlogged Archaeological Woods

“…The S 3 layer in Figure 1 which appears unusually dense also appears intact but that in Figure 2 is degraded, the dense residual material defining the original position of the S 3 layer. The features described in Figures 1 and 2 are similar to those described for the erosion type of bacterial decay of wood in a variety of situations (Singh and Butcher 1991;Singh et aL 1994), including archaeological wood (Blanchette and Hoffmann 1993;Kim and Singh 1994). This together with the fact that the S 3 layer in Figure 2 is also degraded suggests that while S 3 layer is more resistant than the S 2 layer, it is also eventually degraded, and in the absence of this barrier the residual S 2 wall material swells considerably in the presence of abundant water in the cells of waterlogged woods, which would explain the more diffuse nature of the residual S 2 wall material in Figure 2 than in Figure 1.…”

“…3). Erosion bacteria, tunneling bacteria and soft rot fungi appear to be most prevalent among the wood degrading microorganisms present in situations where the wood is saturated with water (Eaton 1994;Singh et al 1992Singh et al , 1994 or is waterlogged (Blanchette and Hoffmann 1993;Donaldson and Singh 1990;Kim and Singh 1994;Mouzouras et al 1986;Nagashima et al 1990;Santhakumaran and Singh 1992). The presence of granular wall residues peripheral to tunnels in Figures 3 and 4 is indicative of bacterial erosion.…”

Investigation of Archaeological European White Elm (Ulmus laevis) for Identifying and Characterizing the Kind of Biological Degradation

“…Research showed that tunneling bacteria (TB) can be found in environments similar to soft rot conditions, while erosion bacteria (EB) are able to degrade wood in environments characterized by a very restricted oxygen supply [9]. They appear to be most tolerant near to anoxic conditions [10][11][12][13], on the other hand, the main wood degraders under waterlogged conditions [13][14][15]. Experiments even suggested that EB can be involved in wood degradation even without free oxygen present, however the process is more intense if oxygen is available [13].…”

Screening for bacterial–fungal associations in a south-eastern US salt marsh using pre-established fungal monocultures

“…Similarly, Mille-Lindblom and Tranvik [25] found increased biomass of fungi and bacteria isolated from Phragmites when each was grown alone compared to when the two microbes were grown together. For example, it has been suggested that bacteria and fungi attack different components of plant material [27,28] and therefore may interact in more general ways to influence decomposition rates. Results from the present study suggest that the observed effects were more likely due to non-specific interactions between the groups, rather than direct interactions involving particular species of bacteria and fungi.…”

“…Results from the present study suggest that the observed effects were more likely due to non-specific interactions between the groups, rather than direct interactions involving particular species of bacteria and fungi. For example, it has been suggested that bacteria and fungi attack different components of plant material [27,28] and therefore may interact in more general ways to influence decomposition rates.…”