Biodeterioration

Biodeterioration

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  What it is?  Deterioration is a phenomenon that occurs in materials of every type, including those used in buildings, metals, stones of monuments and so on.  Any undesirable change in the properties of materials caused by vital activities of organisms is called biodeterioration.  Or it is defined as any form of irreversible alteration, implying a modification in the properties of materials due to metabolic activity and the growth of organisms called biodeteriogens.
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  Abiotic factors thateffects biodeterioration  Humidity,  Light,  Temperature,  The type of substrate,  Ventilation,  Air pollution.  Humidity favors the growth of algae and fungi.  Light, both natural and artificial, is necessary for photosynthetic microorganisms for eg. (Algae and Cyanobacteria), lichens, mosses, and plants
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  Mechanisms of Biodeterioration? Chemicalaggression: It occurs through the decomposition of a substrate and its transformation to final products that is due to microbial metabolism. Such deterioration, exclusive to stonework, is defined as biocorrosion. The metabolites mainly involved in this deterioration mechanism : organic inorganic acids and chelating substances. The acids produced by the organisms react with the material of the stone, generally the insoluble salts, dissolving them and exposing them to be washed away by rainwater.
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  Aggression via mechanics: Stonesexposed to the open air suffer accelerated deterioration of a mechanical type – washing by the rain, thermal excursions in the form of freezing and thawing cycles, and the action of the wind.  Mechanical aggression by living organisms occurs through the growth of microorganisms or parts there of (hyphae of fungi and superior plant roots).
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  Biodeteriogens Biodeteriogens are organismsthat participate in the process of materials, including historical and artistic manufacts. Such organisms are autotrophs and heterotrophs and colonize different types of inorganic (stonework, metals, and glass) and organic materials (paper, wood, parchment, leather, textile, etc.). The main differences in the cellular structure of bacterial and archaeal microorganisms are seen in the composition of the cell wall: peptidoglycan in most Eubacteria and pseudomurein, polysaccharides, proteins,or glycoproteins in the Archaea.
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  Biodeteriogens Prokaryotes Bacteria (eubacteria andarchaebacteria) Chemolithotrophic bacteria:  sulphur oxidising bacteria :sulfuric acid, hydrogen sulfide, elemental sulphur, thiosulfates and inorganic acid  Nitrifying bacteria  Nitrite oxidizing bacteria  Hydrogen bacteria  Ferrobacteria Heterotrophic bacteria Proteolytic and ammonifying bacteria
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  Cellulolytic bacteria Amylolytic bacteria Lipolyticbacteria Denitrifying bacteria
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  Fungi Eumycota Meristematic fungi Phototrophic microorganisms:includes algae and cyanobacteria Lichens Bryophytes Vascular plants
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  Biodeterioration of Inorganic Materials Historicalstone objects (sculptures, buildings,and rocks) and frescoes. - Stones are calcereous in nature. -hygroscopic salts: carbonates,chlorides,nitrates, sulfates. -burning of fossil fuel-acid gases-sulfuric acid that react with calcium carbonate to form calcium sulfate called as gypsum. -particulate matter from atmostphere react with gypsum and form black crust that is due to mixture of aliphatic and aromatic carboxylic acids and polycyclic aromatic hydrpcarbons.
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  Metals All metals arereactive in air expect gold Microbially influenced corrosion causes biopitting. C02,S,H2s,NH and acids are agents. Aerobic conditions: sulfur oxidizing bacteria Anaerobic conditions-sulfate reducing bacteria
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  Biodeterioration- organic materials Paper-cellulose-vegetablefibres -foxing-activity of microbes or oxidation/formation of heavy metals deposits. Wood -cellulose -white rot/brown /soft rot etc.
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  Biodeterioration- composite materials Paintings -that includeseasel and mural objects -lead present in pigments form on oxidation lead oxides. Magnetic tape , optical disk -thin magnetic layer-iron oxide,chromium oxide and polymer that is polyethylene terephthalate. -OD has improved polymer of aromatic polycarbonates that is more durable then aliphatic. -Geotricium fungus is mostly present.
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  Methods of controland prevention Biochemical: compounds of biological origin: antibiotics (active at very low doses, but there is loss of effectiveness over time), enzymes (used especially for cleaning) and pheromones (used to induce males to leave the structures where they nest) are used for infestations in the deep layers of the material where biocides cannot penetrate.
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  Biological: use antagonistor parasitic species to limit the growth of other animal or vegetable species Physical: the use of X-rays with biocidal action or noxious gamma radiation and UV rays Mechanical: the frequent use of manual instruments like scalpels, scrapers, spatulas, and so on. Chemical: like pesticides and disinfectants, more generally called biocides.
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  Thanks
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  Questions ? Define biodetriogens? Describe the factors that increases and decreases the Biodeterioration processes. Describe the mechanism to control process of Biodeterioration for paper, stones and wood.