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A light and electron microscopic study of decayed CCA-treated radiata pine (Pinus radiata) wood from a cooling tower
1994 - IRG/WP 94-10056
An inspection of an industrial cooling tower in New Zealand showed surface decay of 12 year old Pinus radiata wood panels treated with CCA preservative to a retention of around 15 kg/m³ of salt. Wood decay micromorphology typical of that caused by soft rot fungi, white rot fungi, 'stripy' and 'v-shaped' erosion bacteria and cavitation bacteria were all commonly seen using a light microscope (LM). Some evidence of the presence of tunnelling bacteria was also seen but was not as common. Soft rot was largely absent from the wettest regions sampled such as spray-line supports and side panels in close proximity to the spray lines, and erosion bacteria attack was the predominant type in these areas. Transmission electron microscopy (TEM) showed that unusual patterns largely consisting of troughs, depression and granulations in wood cell walls, were in most instances, almost certainly caused by erosion bacteria, but in others, tunnelling bacteria were also present. Several decay patterns seen under light microscope as matrices of fine troughs parallel and perpendicular to the cellulose microfibres were difficult to characterise in terms of previous classification but were also thought to have been caused by erosion bacteria. The distinction made by previous classification between patternms formed by erosion and cavitation bacteria needed to be questioned on the basis of observations made. Whilst the TEM showed that erosion and tunnelling bacteria were often present in close association within the wood cell walls, light microscopy suggested that, in the majority of section examined, all the types seen were clearly seperated by regions of undegraded cell wall. The observations underscore the importance of erosion bacteria in wood decay under the conditions of a cooling tower where in-service timbers are kept constantly wet by the spray from water sprinklers. Also of significance is the great diversity of decay types seen, in particular the presence of cavitation bacteria and white rot fungi has not previously been recorded for high retention CCA treated cooling tower timbers.
A P Singh, R N Wakeling, D R Page


Occurrence and importance of various types of fungal and bacterial decay in CCA-treated horticultural pine posts in New Zealand
1984 - IRG/WP 1234
A detailed microscopical examination has been carried out on samples taken from CCA-treated pine posts exposed in horticultural soils. The following decay types were observed: white rot, brown rot, soft rot, tunnelling bacteria, cavitation bacteria, and bacterial erosion. The occurrence and importance of the various decay types between different regions, and plots within a specific region, varied considerably. Soft rot was the most common type of degrade observed and it was also considered to be the most important decay type in terms of reducing the service life of the posts. Tunnelling bacteria were found to have caused extensive degrade in several properties. Cavitation bacteria were of considerable significance in one property. The other decay forms were regarded as being less important. Their contribution to the degrade in the outer parts of the posts was, however, quite substantial.
T Nilsson


Cavitation bacteria
1984 - IRG/WP 1235
A form of bacterial wood degradation is described. The term "cavitation bacteria" has been coined in order to describe the discrete cavities that are formed within the wood cell walls. The bacteria observed within the cavities appeared to be polymorphic with rounded as well as filamentous forms recognised. TEM studies suggest that the bacteria produce diffusable wood-degrading enzymes. Cavitation bacteria have been found to be widespread in CCA-treated pine posts in horticultural soils in New Zealand. Significant decay due to cavitation bacteria was observed in a large number of the posts.
T Nilsson, A P Singh


Bacterial degradation of wood cell wall: A review of degradation patterns
1990 - IRG/WP 1460
Information from bacterial degradation studies of 60's and 70's was reviewed by Nilsson in 1982. The application of electron microscopy to this area in recent years has provided much useful information and has eliminated earlier scepticism among workers about the ability of bacteria to degrade lignified wood cell walls. Studies using transmission electron microscopy together with those employing 14C-labelled lignins have confirmed that certain types of bacteria have a capacity to degrade intact wood, including timbers which have high lignin or extractive content and are considered naturally durable. It has not been possible thus far to isolate wood degrading bacteria in pure culture and thus their physiology and taxonomic affiliations remain unknown. Laboratory studies using mixed cultures of these organisms and observations of decaying timbers from natural environments have shown the degradation to be of three main types on the basis of microscopic appearances of degradation patterns. The three types are: cavitation, erosion and tunnelling. These patterns and bacteria which produce them during their attack of wood will be described in detail.
A P Singh, J A Butcher


The effect of certain wood extractives on the growth of marine micro-organisms
1977 - IRG/WP 438
S E J Furtado, E B G Jones, J D Bultman


Fungal and bacterial attack of CCA-treated Pinus radiata timbers from a water-cooling tower
1991 - IRG/WP 1488
Transmission electron microscopy of decaying CCA-treated Pinus radiata timbers from an industrial water cooling tower showed presence of a thick biofilm covering some areas of the wood. The biofilm contained various morphologically distinct forms of microorganisms embedded in a slime. The study provided evidence of the activity of soft rot fungi and tunnelling and erosion bacteria in wood cells. The extent of damage to wood cells due to microbial activity varied, combined fungal and bacterial attack having the most damaging impact.
A P Singh, M E Hedley, D R Page, C S Han, K Atisongkroh


Resistance of Alstonia scholaris vestures to degradation by tunnelling bacteria
1992 - IRG/WP 92-1547
Electron microscopic examination of vessels and fibre-tracheids in the wood of Alstonia scholaris exposed to tunnelling bacteria (TB) in a liquid culture showed degradation of all areas of the secondary wall. The highly lignified middle lamella was also degraded in advanced stages of TB attack. However, vestured pit membranes and vestures appeared to be resistant to degradation by TB even when other wall areas in Alstonia scholaris wood cells were severely degraded. The size comparison indicated vestures to be considerably smaller than TB, and we suspect that this may primarily be the reason why vestures in Alstonia scholaris wood were found to be resistant to degradation by TB.
A P Singh, T Nilsson, G F Daniel


Types of decay observed in CCA-treated pine posts in horticultural situations in New Zealand
1984 - IRG/WP 1226
The few reported failures of 11-12-year-old horticultural posts in New Zealand in 1982 were caused by brown-rot. A subsequent survey of CCA-treated posts in all the major horticultural areas has revealed decay of many posts. A microscopic examination of these posts has shown decay by brown-rot, white-rot, soft-rot and bacteria. Several types of bacterial decay have been observed.
J A Drysdale, M E Hedley


Contribution to study of the degradation caused in Pinus spp. poles used in field test
1989 - IRG/WP 1417
The study of the degradation produced by soil natural microflora on wood in contact with it in the field, has been going on for several years now. Our contribution to this aim in the present work has dealt with the possible relationship of the microorganisms in the soil. The microscopic visualization of wood colonization by the microorganisms, and the chemical analysis of the degraded wood compared with the undergraded.
M T De Troya, A Garcia, M J Pozuelo, A M Navarrete, A Cabanas


Observations on the failure of anti-sapstain treated timber under non-drying conditions
1990 - IRG/WP 1437
A range of bacteria and yeasts were isolated from antisapstain treated timber and fresh sawdust. Solution samples containing 100 ppm of TCMTB in a nutrient medium were inoculated with these organisms and incubated at 25°C for 5 days. The levels of TCMTB remaining in solution were determined by HPLC analysis after this time. Results indicated high losses of active ingredient for a range of organisms. These results suggest that active biodetoxification of organic biocides could occur in a short period of time during storage of antisapstain treated timber under favourable conditions. The implications of these results are discussed.
G R Williams


Test procedure to determine the effect of timber substrate on the effectiveness of different preservatives in sea-wate
1975 - IRG/WP 414
R A Eaton


Soft rot and bacterial decay in preservative treated eucalypt power transmission poles
1982 - IRG/WP 1155
Bacterial type decay was observed in CCA and PCP treated eucalypt power transmission poles. Detailed observations made with the SEM revealed bacterial colonisation and decay, especially in fibres. Plug samples taken from poles throughout Queensland were examined for preservative retention and presence of soft-rot decay. The severity of decay was different according to location, retention and species.
L E Leightley


Microbial biofouling of 10-40% naphthalene in creosote treated and untreated wooden pilings in the marine environment
1978 - IRG/WP 442
R R Colwell, P L Fish, D A Webb, A J Emery


Proposed test procedure to determine the effect of timber substrate on the effectiveness of a copper/chrome/arsenic preservative in seawater
1975 - IRG/WP 411
R A Eaton


Bacteria and wood. A review of the literature relating to the presence, action and interaction of bacteria in wood
1971 - IRG/WP 101
S E Rossell, E G M Abbot, J F Levy


Ultrastructural and TEM-EDAX studies on the degradation of CCA treated radiata pine by tunnelling bacteria
1985 - IRG/WP 1260
An ultrastructural study was carried out on bacterial attacked Pinus radiata stakes treated with a high level (24.7 kg/m³) of Tanalith NCA preservative. The purpose of the investigation was to determine whether the organism possessed intracellular and/or extracellular detoxification mechanisms in order to overcome the high levels of copper, chrome and arsenic present within the wood fibre walls. Correlated T.E.M. and T.E.M.-EDAX studies showed most of the preservative elements to remain outside the bacteria associated with bacterial tunnel wall and cross-wall extracellular secretions. T.E.M.-EDAX showed the levels of preservative elements present in the tunnel walls and cross walls to often greatly exceel that recorded in neighbouring S2 cell wall regions, while studies on the bacteria showed that only copper and very low levels of chromium and arsenic had entered the cells. Observations suggested that the metals found within the cells were associated with electron-dense deposits or inclusions within the nuclear region or cell cytoplasm, the deposits often containing high levels of phosphorus and calcium together with lesser levels of other cations. The study also provided evidence for the direct visualisation of CCA preservative elements within fibre walls using T.E.M. without any form of secondary chemical enhancing, and in addition, considerable new information on the nature and structure of the single celled, Gram-negative, motile bacteria involved in the decay.
G F Daniel, T Nilsson


Short term preconditioning of preservative-treated wood in soil contact in relation to performance in field trials
2000 - IRG/WP 00-20185
The effect of pre-exposure to primary colonising micro-organisms on preservative-treated wood, prior to a basidiomycete decay test, was determined by preconditioning in two soil types. Scots pine EN 113 blocks treated with 3 model systems (a triazole, a copper quaternary compound and a copper boron triazole) were leached according to EN 84 and subjected to 6 weeks and 8 weeks burial in either John Innes no. 2 (a loam-based horticultural compost) or soil from the Simlångsdalen field site in Sweden. The samples were then tested according to the method described in EN 113. Selective isolations were also performed after soil exposure and compared with those from a longer term field trial. Preconditioning lowered the effectiveness of the 2 copper containing preservatives. Some effect of soil pre-exposure could be noted with the triazole but this was limited. The fungal isolations from preconditioned EN 113 blocks and field exposed stakes were a similar mixture of soft rot and mould fungi. Bacteria were commonly isolated from the preconditioned wood. The role of these micro-organisms in the modification of the preservatives is currently being investigated.
S Molnar, D J Dickinson


Ultrastructure of the attack of a naturally durable timber by tunnelling bacteria
1990 - IRG/WP 1462
The attack of the wood of Eusideroxylon zwageri, a naturally durable species, by tunnelling bacteria (TB) was examined by light microscopy and transmission electron microscopy. Observations were made primarily on fibres. Parenchyma were included in some cases. Both fibres and parenchyma are rich in extractives. In fibres, extractives are primarily present in the lumen. The amber colouration of fibre walls under the light microscope suggests that extractives may also permeate fibre walls. In parenchyma, extractives are present in large amounts in the lumen. Inner areas of parenchyma walls are also heavily permeated. The degradation of Eusideroxylon zwageri wood is markedly slower than any wood species we have examined before. However, in advanced stages of TB attack all areas of the fibre, except corner middle lamellae and extractive filled lumen, are heavily degraded. The degradation of Eusideroxylon zwageri wood involves other differences. The TB attack of the fibre wall starts from the S1 layer moving inwards and the tunnels formed vary greatly in their form, ranging from long and relatively straight to "S","V", hook, folded and convoluted forms. These variations from previously observed appearances most likely reflect differences in the thickness and chemical composition of the fibre wall of Eusideroxylon zwageri wood from the woods examined previously.
A P Singh, T Nilsson, G F Daniel


Ultrastructural observations on wood-degrading erosion bacteria
1986 - IRG/WP 1283
G F Daniel, T Nilsson


Biological control of blue stain on wood with Pseudomonas cepacia 6253. Laboratory and field test
1989 - IRG/WP 1380
Pseudomonas cepacia strain 6253 was tested as a biological control agent on wood samples under laboratory conditions, as well as in the field. In the laboratory this bacterium controlled blue stain on Pinus radiata, but field test were not totally satisfactory. However, after 2 months of field test, the test samples were 1/3 to 1/2 less stained then the control samples.
R Benko


Isolation and identification of the fungal flora in treated wood
1976 - IRG/WP 144
J F Levy


Copper based water-borne preservatives: The use of a thin section technique to compare the protection of wood by copper based preservatives against soft-rot and bacterial decay
1987 - IRG/WP 2286
This paper describes the techniques developed and gives examples of results obtained for the performance of copper based wood preservatives against both the bacterial and fungal hazards.
A M Wyles, D J Dickinson


Bacteria as possible organisms for biological control of blue stain
1988 - IRG/WP 1339
The article discusses the possibilities of biological control of blue stain. Besides using some antagonistic fungi, the possibility of using antagonistic bacteria, which offer still greater possibilities, should not be overlooked. Tests performed have shown that some bacteria from the genera Streptomyces and Pseudomonas have a strong antagonistic effect of blue stain.
R Benko


Fungal defacement of water-stored softwoods
1993 - IRG/WP 93-10009
Sapstain, mould and basidiomycete defacement of untreated sawn boards of Scots and Corsican pine was recorded during a 14 week field trial. Boards were cut from freshly felled logs and from logs previously maintained under water sprinklers for 6 months and ca. 4 years. The incidence of sapstain defacement or the freshly felled wood was very servere aftcr 2 weeks and remained so throughout the board trial. Fungal defacement of wood previously stored under sprinklers for 6 months was progressive and was severe by 14 weeks. In contrast, the level of defacement of boards from long lerm water-stored logs remained very low after 14 weeks exposure. The marked differences in susceptibility to fungal infestation of boards from freshly felled and water-stored logs are discussed in terms of wood sugar levels and the bacterial populations present in the wood.
M A Powell, R A Eaton


Studies on the biological improvement of permeability in New Zealand grown Douglas fir
1983 - IRG/WP 3231
This report outlines progress towards optimizing conditions for water storage of New Zealand grown Douglas fir with the aim of improving permeability to water-borne preservatives, in particular CCA. Small scale laboratory tests are in progress but the need to scale up to potential commercial applications is being considered. Mixed populations of bacteria isolated from 10 week water sprinkled Douglas fir are being used to inoculate green, sterile timber. Environmental parameters such as pH, temperature and nutrient status are controlled to evaluate optimum conditions of growth, enzyme production and pitmembrane degradation leading to permeability improvement.
K J Archer


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