International Biodeterioration最新文献

The insecticidal value of the castor oil plant (Ricinus communis) in controlling the termites which damage the wood of Mangifera indica and Pinus longifolia was examined. In comparative trials, the order of insecticidal activity was DDT=BHC > castor oil + castor cake (1:1) > castor oil > castor leaves > castor cake > neem oil > neem leaves. All treatments significantly reduced weight loss in wood pieces exposed to termites.

Recognition of the importance of microbiological factors in the deterioration of stone in buildings and monuments is comparatively recent, with attention focusing on the growths and the kinds of deterioration they cause, rather than on their elimination. This paper outlines considerations in the development of treatments for the elimination of microbiological growths from building stone. The goals of biocidal treatment in the context of architectural conservation are delineated, and limitations in the selection and application of biocidal treatments for architecture are discussed; conditions of work in the USA are emphasized. Directions for future work that would be of interest to architectural conservators are suggested, including evaluation of commonly used biocidal materials and development of comprehensive literature reviews.

The presence of bacteria and fungi in the metal-working fluid (MWF) of a large central tank (150 m³) in an engineering factory was studied over 3 years with the aim of microbial prevention. During the first year it was possible to prevent the growth of bacteria and fungi by the use of formaldehyde (270 ppm) and sodium Omadine (60 ppm).

During the subsequent years the antimicrobial capacity of alkanolamines was explored. In laboratory tests it was found that the antimicrobial activity was greatly enhanced at higher pH values. Butylethanolamine and dimethylamino-methyl-propanol had the highest antimicrobial potency of the alkanolamines, in vitro. Butylethanolamine in combination with a pH higher than 9 was also an efficient antimicrobial agent when used in MWF under workshop conditions. The enhanced antimicrobial activity of the alkanolamines at higher pH offers both a non-expensive way of microbial control and a mechanism for selective toxicity.

It is becoming common practise to select plastics such as unplasticised polyvinyl chloride (PVC) for construction of submarine pipes and intakes, especially for service in conditions where wood is susceptible to attack. Recent cases indicate, however, that these materials may not necessarily be immune. Failure of PVC piping on the north coast of Java from attack by boring pholads, Martesia striata, occurred in approximately one year. It appears to be the most rapid yet reported. Destruction by marine borers within one to three years at this and other polluted harbour locations around the world lead us to conclude that eutrophication of the environment from anthropogenic sources can accelerate attack and biodeterioration of marine materials.

Various bacteria, streptomycetes and fungi were isolated from the damaged frescoes and building materials in the Cathedral of the Nativity of the Virgin at the Pafnutii-Borovskii Monastery. Growth of micro-organisms was associated with the formation of a compact yellowish-white coating on the cleared and restored frescoes, plaster and brick, and with the powdery destruction of building stone and brickwork at the lower parts of the walls. Evidence was given to support the hypothesis that, although heterotrophic micro-organisms could use organic substances of dust, admixtures in plaster, binding medium of paints and restoration material as nutrient sources for growth on inorganic building materials and frescoes, it is in fact the trophic interrelationships which play the main role within microbial communities of this type. It was demonstrated that fungi and streptomycetes could produce enzymes hydrolysing bacterial and fungal cell walls as well as bacterial extracellular polysaccharides.

A bacterium Ochrobactrum anthropii isolated from contaminated fuel had a strong ability, associated with a cell-bound component, to emulsify hydrocarbon: water mixtures. This was only released into the medium following extraction involving sonication and ultracentrifugation. The component was partially purified using a fast protein liquid chromatography system. From this and polyacrylamide gel electrophoresis, it was found to be essentially a protein of molecular weight 1·04 × 10⁵. Enzyme digests of the crude extract prepared using protease revealed that a protein component was essential for activity. The emulsifying ability of the crude extract was assessed against a variety of hydrocarbon: water systems utilising aliphatic, aromatic and cyclic hydrocarbon. A broad range of hydrocarbons was emulsified.

A study of lichens growing on the cloister of Silos Monastery (Burgos, Spain) was undertaken in order to gain a better understanding of the mechanisms by which lichen thalli alter the surface of monuments. Tiny pieces (flakes) of the stone surface, some of which bore visible thalli of Caloplaca decipiens and Lecanora albescens, were studied with scanning electron microscopy, transmission electron microscopy and X-ray microanalysis. Transmission electron microscopy showed the spatial relationship between the lichen and the rock which forms the abacus of the capital. Deposits of electron dense material, whose chemical compositron revealed a predominance of calcium, were visible among the hyphae as well as in the vicinity of algal cells. Other structures with different elemental composition were also observed. It was possible to observed structures resembling fungal hyphae inside flakes of material which showed no macroscopic evidence of lichens.

Biodegradability of used and unused lubricating oil was assessed with a mixed culture of bacterial isolated from the used oil. Flow rate determination indicated that used oil flowed faster at both low (30°C) and high (70°C) temperatures than unused oil. Hear transfer experiments showed that used oil conveyed heat more readily than unused oil so when the temperatures of used oil were 38, 67 and 97°C, the corresponding temperatures of unused oil were 35, 55 and 72°C, respectively. Utilisation of used oil by the mixed culture resulted in higher total viable counts (20 × 10⁷CFUml⁻) and pH drops (7·3–5·5) than those of unused oil (c.11 × 10⁷CFUml⁻¹andpH 7·3–6.0). Analysis by computerised gas chromatography confirmed that used oil has been modified while in service and is more biodegradable than unused oil. The formation of several novel compounds which could be detected by gas chromatography resulted from microbial growth on used oil.

The microbial colonisation and contamination of rocks is basically controlled by environmental impacts, such as type of rock, climatic conditions and edaphic factors. Anthropogenic inorganic and organic air pollutants, specifically aliphatic and aromatic hydrocarbons, accelerate chemoorganotrophic biodeterioration processes on exposed rocks of historical monuments. Besides the surface-controlled excretion of corrosive organic acids, stone-colonising microorganisms promote physico-chemical rock decay processes by the excretion of water absorbing extracellular polymeric substances (EPS) containing surface tension reducing compounds. Capillary water uptake and consequently the water holding capacity of rock is increased and possibly influenced by the above mentioned mechanism. The importance of these findings for the mechanisms of rock decay on historical monuments is discussed.