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Microbiological degradation of wooden piles in building foundations
1988 - IRG/WP 1370
White rot, soft rot and bacterial attack have been detected in softwood piles under buildings. In some cases bacteria were found to be the main degradation organisms in the studied piles. The water content of degraded piles was very high. The compression strength was quite low also in the piles deteriorated by bacteria. The density of wood was very variable, and the degree of degradation could not be evaluated according to density analyses.
L Paajanen, H Viitanen

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

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

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

IRG/COIPM INTERNATIONAL MARINE TEST - to determine the effect of timber substrate on the effectiveness of water-borne salt preservatives in sea-water: Final report
1987 - IRG/WP 4133
Three timbers chosen as reference species were treated with 3, 6 and 10% solutions of CCA and CCB preservatives and exposed for up to 93 months at 8 tropical and temperate marine sites. Eleven local species treated in the same way were exposed at 4 of the 8 sites. There was no apparent difference in performance between CCA and CCB treated specimens. The severest test site was Panama Canal but marine borer damage of specimens was recorded at all the test sites. Treated specimens of the reference species Alstonia scholaris and Pinus sylvestris were markedly superior in performance at all sites and Homalium foetidum was considered the best local species. Along with the reference species Fagus sylvatica, treated specimens of the remaining local species performed relatively poorly. All treated species were attacked by soft rot fungi, except treated Alstonia scholaris and Homalium foetidum which were superficially decayed by bacteria. The relative success of treated Alstonia scholaris in this trial is attributed to its permeability characteristics and acceptance of high preservative loadings, even preservative distribution and its high lignin content.
R A Eaton

Bacterial wood degradation by a pure culture
1995 - IRG/WP 95-10093
A single-celled bacterium isolated from lake water yielded cell wall degradation in Scots pine sapwood samples. The bacterium attacked all cell wall layers in one month of laboratory culture. It was identified as Aureobacterium luteolum.
O Schmidt

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

Bacterial staining of samba (Triplochiton scleroxylon)
1988 - IRG/WP 1362
Red- and green-stained areas on Samba wood have been tested by IR, X-ray and Neutron Activation Multielement Analysis. No difference could be seen between stained and unstained areas. The red- and green-staining seem to be related to the bacteria Pseudomonas aeruginosa which were isolated from both red- and green-stained areas on the wood surfaces.
K Hansen

The Role of Coformulants in Preventing Bacterial Biotransformation of IPBC
2002 - IRG/WP 02-10436
The inhibitory effects of disodium tetraborate decahydrate and benzalkonium chloride (BAC), two common coformulants of IPBC in antisapstain treatments, on an IPBC-transforming enterobacterial isolate ‘W1’ were determined by their effect on the specific growth rate constant in vitro. The IC50s of IPBC, BAC and borate were found to be 0.46, 0.026 and 5.7 mM respectively. The IC50 of the Arch antistain product AntibluTM Select was 0.024 mM, based on its BAC content. Although their IC50’s were significantly different, it was clear that the vast majority of the bacterial toxicity of the AntibluTM Select was due to its BAC content. The degradation of 0.4 mM IPBC by the bacterium W1, as measured by the accumulation of its degradation product, iodide, in liquid culture, was completely inhibited by BAC concentrations greater than 18 μM, and the toxicity of the spent culture medium to Aspergillus niger, as measured by an antibiotic assay disc assay, was not ameliorated above this concentration. Below 18 μM, the toxicity of the spent broth was significantly reduced, and the accumulation of iodide occurred rapidly. Demonstrating the toxicity of BAC to bacteria, and its consequent inhibition of IPBC degradation in vitro, are indicative of the importance of coformulation in controlling bacteria that might otherwise cause preservative loss, and of their significance in determining the ultimate environmental fate of cobiocides.
S R Cook, D J Dickinson

Patterns of bacterial attack in preservative treated eucalypt power transmission poles
1984 - IRG/WP 1223
Patterns of bacterial decay have been examined using light and scanning electron microscopy. Two morphologically distinct patterns have been recognised in preservative treated eucalypt power transmission poles. Bacterial Decay I (BDI) involves the removal of the secondary wall layers initiating with erosion of the S3 layer from the cell lumen. As decay progresses the S2 layer and S1 layer are degraded until only the primary wall middle lamella complex is left intact. Bacterial Decay II (BDII) appears to be initiated in the S2 layer of the secondary wall. Characteristic cavities are formed in the S2 layer with the S3 layer appearing to be unaffected. Coalescence of the S2 cavities results in the S3 layer and primary wall-middle lamella complex being the only cell wall components remaining. Both BDI and BDII have been observed in CCA and PCP treated eucalypt poles, situated in a variety of natural environments throughout Queensland. The significance of the widespread occurrence of bacterial decay is discussed. In addition tunnelling bacteria type decay patterns have been observed in CCA treated Pinus elliottii Englm. test stakes.
G A Willoughby, L E Leightley

Ultrastructural aspects of bacterial attacks on an archaeological wood
1993 - IRG/WP 93-10007
Transmission electron microscopy of wood from a Chinese ship submerged in the mud for over 900 years showed bacteria to be the main factor for its deterioration. The micromorphology of degraded wood cell walls was similar to that observed during the attacks of wood by erosion bacteria. Other bacterial forms, previously considered lo be scavenging bacteria, were also abundant in degraded areas of the wall. The observations on the breakdown of the waterlogged archaeological wood are discussed in context with the available information on bacterial degradation of wood under near-anaerobic conditions.
Yoon Soo Kim, A P Singh

Examining environmental conditions and the biodeterioration of historic waterlogged wood: the Kolding Cog
2002 - IRG/WP 02-10441
Survival of waterlogged wood from thousands and in rare cases millions of years presents scientists with a unique opportunity to examine wood specimens which, due to select properties of the wood itself and/or the depositional environment, have not been completely degraded. This paper discusses the biodeterioration of a submerged shipwreck buried in Kolding Fjord, Denmark for the past 1000 years. Sections taken from two waterlogged timbers within the wreck site were physically evaluated to determine the extent of degradation in the timber at various depths below the sediment-water interface. The condition of the wood specimens was then compared to environmental characteristics, such as oxygen, hydrogen-ion (pH), and sulfide concentrations. The baseline of information gained from the systematic study of these timbers provides valuable information for the future storage and conservation of the shipwreck.
B A Jordan, D J Gregory, E L Schmidt

Some experiences with attack of microorganisms on wooden constructions supporting foundations of houses and bridges
1997 - IRG/WP 97-10232
Reconstructions of bridges and public buildings or damage of houses during the construction of subway lines in Berlin have led to a number of inspections of wooden foundations, mostly pine or spruce piles, representing service lives of between ca. 70 and 140 years. In all cases bacterial attack was found both in wood submerged in ground water and in surface water. The extent of deterioration differs considerably in round wood and sawn wood and, furthermore, depends on the type of soil or water surrounding the wood. Within 140 years sawn scots pine sapwood can be completely destroyed by bacteria occurring below the level of the water table, whereas scots pine heartwood is remarkably durable. On sawn wood, only a small outer surface layer of the heartwood is damaged. In scots pine piles which had been installed about 110 years ago under the Reichstag building in Berlin bacterial attack produced bending strength losses of up to nearly 50% and crushing strength losses parallel to the grain of up to 55% in the outer sapwood as compared to the heartwood.
M Grinda

Enzyme systems of bacterial isolates from ponded logs - Potentials of pectin and/or starch degradation
2000 - IRG/WP 00-10378
This paper deals with the degradation potentials of wood constituents by the bacterial isolates from ponded logs. The potentials to degrade pectin as a constituent of pit-tori as well as starch existing in ray parenchyma cells in the areas of sap- and transition wood with the isolates were examined. The pectinase activity was investigated by means of the degradation degree of a carrot strip used as a single carbon source in a liquid medium. The amylase activity was studied by the colour change on the iodostarch reaction in an agar medium containing soluble starch as a single carbon source. The results suggested that these substrates were degraded sequentially by plural bacterial species that invaded in the logs during ponding.
S Doi, S Ohta

Bacterial brown stain on sawn timber cut from water-stored logs
1992 - IRG/WP 92-1532
Brown stains which appear on the surface of sawn radiata pine cut from water-stored logs were identified as tannin-like compounds. They are derived from bacterial breakdown of flavanoid-glucosides. When timber is sawn from infected logs, the free flavanoids migrate to the wood surface as the timber dries. There, they condense and oxidise to form permanent brown discolourations. Stains occurred on sawn timber between 4 and 8 weeks of storage under water sprinklers. Kiln-drying resulted in more intense staining than did air-drying. Stain intensity was less in winter-stored logs than in summer-stored logs. Sprinkling logs with fresh water or debarking logs before storage had little consistent effect on propensity to stain
M E Hedley, R Meder

Degradation features of waterlogged archaeological compression wood
1998 - IRG/WP 98-10258
The degradation characteristics of waterlogged archaeological compression wood excavated in South Korea were examined by transmission electron microscopy (TEM) and confocal laser scanning microscopy (CLSM). Degradation of Pinus compression wood occurred mainly in the inner part of S2 layer. In contrast, the outer part of S2 layer remained relatively intact. CLSM and TEM showed the erosion type of bacterial attack to be dominant in the secondary cell walls of both severe and mild compression wood. However, in some cases middle lamella was also degraded, which suggests that other forms of microbial attacks, such as bacterial tunnelling, were also present. Bacterial erosion in the severe compression wood was mainly confined to the inner part of S2 layer whereas in the mild compression wood it also extended into outer part of S2 and the S1 layer. The extent of erosion correlated to the differences in the amount and distribution of lignin, particularly in the outer S2 layer between the severe and mild compression wood cells. These features are compared with the degradation of normal Pinus wood.
Yoon Soo Kim, A P Singh

Effect of volatiles from bacteria and yeast on the growth and pigmentation of sap-stain fungi
2000 - IRG/WP 00-10331
Sapstain fungi cause deterioration of wood due to colonisation by pigmented hyphae but without producing significant strength losses. This is due to the production of melanin in the fungal cell walls of the staining fungi. Any biological control strategy targeted against this type of deterioration would therefore be considered successful if it inhibited either fungal growth or pigment production. Previous work has established that specific bacterial and yeast isolates selected on the basis of agar screening studies could significantly reduce levels of staining in wood block tests. This paper presents the results of a study to examine the role of volatile organic compounds (VOCs) produced by three bacterial and three yeast isolates on the growth and pigment production by a range of five sap-stain fungi on three media types. Results were variable and dependent on media type. Of all combinations tested Sclerophoma pityophila showed greatest levels of inhibition when exposed to bacterial VOCs when grown on tryptone soya agar. On some occasions, although no significant inhibition of growth was produced, the level of pigmentation of the sapstain colony as measured using image analysis equipment was significantly reduced compared with corresponding controls. The implications of this work for the biological control of sapstain fungi are discussed.
A Bruce, R E Wheatley, S Verrall

Assessment of treated wood leachates genotoxicity with a bacterial test
1997 - IRG/WP 97-50089
Genotoxicity is known as the damage caused by environmental stressors (biological, chemical and physical) on the genetic material of an organism. This toxicological effect can be assessed by a lot of biological assays and especially by bacterial tests. These tests are frequently performed on environmental samples or on pures substances and are in that case, strongly correlated to the carcinogenic effect obtained on mammals. A leachate procedure (EN 1250-2) was applied to treated wood (Pinus sylvestris, EN 113 type) in order to simulate and predict the loss of active ingredients through percolation or lixiviation processes. The genotoxicity of the leachates was evaluated with a bacterial mutagenecity test performed on Vibrio fisheri dark mutant and consisted in measuring the light emission of the revertant organisms. Three types of formulations were used for the wood impregnation: a Copper Chromium Arsenic (CCA) water based formulation, an organic and a creosote type formulation. Genotoxicity of the leachates is presented and a correlation between the presence of direct or indirect mutagenic compounds in water and the biological response is then approached.
P Marchal, C Martin

Bacterial degradation of Pinus radiata compression wood
1996 - IRG/WP 96-10153
An inspection of twelve year old, CCA-treated Pinus radiata wood from an industrial cooling tower showed extensive surface decay of wood. Electron microscopic examination of decaying compression wood indicated that compression wood cells were attacked exclusively by bacteria, which were of erosion and tunnelling types. As compared to the normal wood, compression wood appeared to be more resistance to the bacterial attacks present. The highly lignified outer S2 wall and the middle lamellae in the compression wood tracheids were resistant to erosion bacteria, and were only occasionally attacked by tunnelling bacteria. These observations are discussed in relation to the information available on the structure and chemical composition of compression wood.
A P Singh, R N Wakeling

16S rRNA Analysis of the Bacteria Associated with Biocide Degradation
2004 - IRG/WP 04-10543
The bacterially mediated degradation of the new anti-fungal biocide, bethoxazin, was studied in vitro, by means of 16S rRNA PCR-amplification and cloning techniques. Woodblocks impregnated with a subtoxic concentration of bethoxazin were incubated in compost, and the micro-organisms associated with the wood after 6 and 12 weeks was studied. It was found that after 6 weeks the wood contained a large number of proteobacteria, including Pseudomonas fluorescens, Bordetella petrii, Asticcacaulis biprosthecium and Alcaligenes spp. These organisms appear to be the dominant organisms involved in bethoxazin detoxification. After 12 weeks, the population of bacteria was found to have altered considerably, with the dominant bacteria being identified as Afipia, Rhizobium and Verrucomicrobium. This population is thought to have developed after the biocide had been detoxified and represents a succession in the wood, outcompeting the previous detoxifying population.
D F Wallace, D J Dickinson

The Bacterial Biotransformation of IPBC
2002 - IRG/WP 02-10437
The bacterial biotransformation of the biocide IPBC, widely used as an antisapstain wood preservative, was investigated in bacteria isolated from failed wood, soil experiencing IPBC wash-off, and John Innes No. 2 compost. Nine strains of bacteria were isolated, belonging to the genera Alcaligenes, Enterobacter, Microbacterium and Pseudomonas. The sole organic degradation product in an enteric bacterium ‘W1’, isolated from failed wood, was PBC, which was produced at 1:1 stoichiometry. No further degradation products were isolated: PBC appeared to be the terminal product of transformation. Incubation of 0.8 mM IPBC in mineral medium with W1 for 90 hr caused the IPBC concentration to fall to undetectable levels, and the toxicity of spent broth was reduced to zero for four target fungi as measured by an antibiotic assay disc bioassay. Furthermore, the toxicity of PBC to the fungi as bioassayed, was c. 1/1000 that of IPBC. The widespread ability of common soil and wood bacteria to transform IPBC to less toxic products is an important contribution to an understanding the environmental fate of IPBC and its continued use under the auspices of the European Biocidal Products Directive (BPD).
S R Cook, J Sullivan, D J Dickinson

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

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

Biological control of sapwood-inhabiting fungi by living bacterial cells of Streptomyces rimosus as a bioprotectant
1992 - IRG/WP 92-1564
The objective of this study is to evaluate the efficacy of antifungal activity of living bacterial cells for the protection of wood against sapwood-inhabiting fungi. The following sapwood-inhabiting fungi were selected: sapstain --Ceratocystis coerulescens, Ceratocystis minor, Ceratocystis pilifera, and Aureobasidum pullulans; mold fungi --Aspergillus niger, Penicillium spp, and Trichoderma spp. Living bacteria cells as a bioprotectant were studied in the laboratory using Southern pine and sweetgum block tests, and in field exposure trials with green pine log sections. Living bacterial cells inhibited spore germination, and therefore discoloration in laboratory wood block tests and in pine log sections exposed in field tests.
S C Croan, T L Highley

Ability of heartwood extractives to inhibit the growth of a bacterial symbiont of Teredo navalis
2000 - IRG/WP 00-10369
Shipworms are important destroyers of wood in the marine environment, and wood users have long sought methods for preventing or limiting their attack. While heavy -duty wood preservatives are highly effective against these organisms, there is increasing concern about risks to non-target organisms. This has resulted in a gradual shift away from broadly toxic materials to either alternative materials or to woods with naturally durable heartwood. Naturally durable woods contain an array of chemicals that have the potential to target specific marine borer life stages. One possible target for control is to inhibit the growth of a shipworm symbiont required for wood degradation. This symbiont, a cellulolytic nitrogen-fixing bacterium, might be sensitive to specific compounds present in naturally durable woods. In this study, the potential inhibition of the symbiont by extracts from the heartwood of various wood species was compared with that of Aspergillus niger. Only a few of the materials inhibited the symbiont, suggesting that some of the woods resist attack through more direct action against the marine borer.
C S Love, A R Sipe, S C Cary, J J Morrell

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