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Biodeterioration
1.
2. What it is ?
๏จ Deterioration is a phenomenon that occurs in
materials of every type, including those used in
buildings, metals, stones of monuments and so on.
๏จ Any undesirable change in the properties of
materials caused by vital activities of organisms is
called biodeterioration.
๏จ 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.
3.
4.
5.
6. Abiotic factors that effects
biodeterioration
๏จ Humidity,
๏จ Light,
๏จ Temperature,
๏จ The type of substrate,
๏จ Ventilation,
๏จ Air pollution.
๏จ Humidity favors the growth of algae and fungi.
๏จ Light, both natural and artificial, is necessary for
photosynthetic microorganisms for eg. (Algae and
Cyanobacteria), lichens, mosses, and plants
7. Mechanisms of Biodeterioration?
๏Chemical aggression:
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.
8. ๏Aggression via mechanics:
Stones exposed to the open air suffer accelerated
deterioration of a mechanical type โ
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).
9. Biodeteriogens
๏Biodeteriogens are organisms that 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.
13. Biodeterioration
of Inorganic Materials
๏Historical stone 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.
14. Metals
๏All metals are reactive 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
16. Biodeterioration-
composite materials
๏Paintings
-that includes easel 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.
17. Methods of control and 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.
18. ๏Biological: use antagonist or 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.
20. 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.
