PRINCIPLES OF BIODETERIORATION

Department of Microbiology

Niger Delta University

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COURSE OUTLINE
• The course covers the following areas:

• Principles of microbial deterioration of materials

• Materials subject to microbial deterioration such as food, jet fuels,
paper, paints, textiles and leather, metals, etc
• Factors favoring deterioration of materials as well as major microbial
groups involved in deterioration.
• Impact of processing and new technologies on biodeterioration
• Biodeterioration control

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COURSE OUTLINE
Course Objectives/Goals

The objectives of this course are to:

• Understand the concept of biodeterioration.
• Know the materials involved in each type of biodeterioration.
• Differentiate between the types of biodeterioration and their mechanisms
of action.
• Enumerate the different micro and macro organisms involved in
biodeterioration.
• Gain requisite knowledge in controlling biodeterioration of different
materials.
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What is biodeterioration?
• The word has only been in use for about 40 years

• It describes processes which have affected humankind ever since

we began to possess and use materials.

• First definition of biodeterioration was proposed by H. J. Hueck in

1965

• Biodeterioration is different from Biodegradation 4

DEFINITIONS
•Biodeterioration is ‘any undesirable change in
the properties of a material caused by the vital
activities of organisms’.

•Biodegradation is ‘the harnessing, by man, of

the decay abilities of organisms to render a
waste material more useful or acceptable’.
Biodegradation is the breakdown of organic matter or substances into
smaller and simpler substances via a biologically catalyzed reduction
in the presence of living microorganisms. 5
DEFINITIONS
• Both definitions involve humankind, in a negative or harmful way
in the case of biodeterioration and

• in a positive or useful way in the case of biodegradation.

• Both definitions also involve materials.

• Materials are any form of matter, with the exception of living

organisms, which are used by humankind.

• All materials (and processes) will have an intrinsic value and thus
there is an important economic dimension to biodeterioration.
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MATERIALS OF INTRINSIC VALUE

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MICROBES-Drivers of decomposition in nature

• Breakdown organic materials in nature into smaller utilizable substrates

• Clean up the environment

• Ensure the cycling of Nutrients trapped in bodies and the sustenance of Life
on earth

• Microbes are the 2nd most powerful, only after God

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MICROBES-Drivers of decomposition in nature

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Decomposition for
sustenance

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• Bioremediation driven by Microbes

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DETERIORATION AND PATHOLOGY

• In the case of pathogens there is usually a clear reaction from the living
tissue affected, involving an attempt to limit or remove the pathogen,

• whereas in the case of deteriogens of materials there is no such reaction.

• This is one of the fundamental differences which separates biodeterioration

of materials from plant or animal pathology.

• In both biodeterioration and pathology, damage is caused in some way, and

it is this damaging involvement of organisms on materials which is
considered in this course.
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DETERIORATION-Historical perspective
• Many of early humankind’s materials were derived from plants and animals,
with minimum processing.

• Such materials were particularly vulnerable to attack by organisms, and

biodeterioration may have played an important role in the ways in which early
civilizations were able to develop and spread.

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DETERIORATION-Historical perspective
• Early control of biodeterioration utilized the basic principles which still hold
good today.

• Food was either eaten fresh before any form of deterioration could occur,
dried to minimize the growth of microorganisms, or physically protected from
insects and rodents by use of sealed jars and bins.

• Salt and spices were used as preservatives.

• In the non-food area, early examples of control included the use of burning
sulfur as a general fumigant and the use of copper sheeting on ships’ hulls to
provide a physical barrier to boring organisms.
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DETERIORATION-Classification
• In the world today, there is a wild range of materials.
• Many are complex and much changed from the original raw materials from
which they were derived.
• New environments are, for good or bad, being exploited; roads and cities are
being built in rain forests, structures are erected in seas and oceans for oil
exploration and extraction, and high-rise office and apartment blocks take
advantage of new building techniques.
• These new materials, their uses, and environments present biological
problems, and together with the enormous range of organisms in the
environment it is useful to classify the basic types of biodeterioration which
can occur.
• It should be noted, however, that any such classification scheme is artificial,
and one organism may cause more than one type of biodeterioration
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DETERIORATION-Classification

Wood Rot Fungi on growing

on furniture

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DETERIORATION-Classification
PHYSICAL OR MECHANICAL BIODETERIORATION
• In this instance, the organism quite simply disrupts or distorts the material by
growth or movement and does not use it as a food source.

• There are few, if any, serious examples of such damage caused by

microorganisms, but one which might be quoted is the expansion of microbial
masses between rock layers, leading to spalling (breaking) of the surface.

• The growth and activity of the microorganisms on monuments or stone

surface results in five major alterations: bioweathering (stone dissolution),
staining or color alteration, surface alterations (pitting, etching, stratification
etc), biocorrosion and transformation of crystal into small size one
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DETERIORATION-Classification
PHYSICAL OR MECHANICAL BIODETERIORATION

• Examples caused by higher organisms include the cracking of

underground pipes by tree roots, the gnawing of electrical cables,
cinder blocks, plasterboard, and wood by rodents, and bird strikes on
aircraft.

• This latter example illustrates the point that biodeterioration is not

necessarily caused by any ‘conscious’ process of the organism.
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DETERIORATION-Classification

• Cinder blocks
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DETERIORATION-Classification
FOULING OR SOILING (AESTHETIC BIODETERIORATION)
• Here, the objection is simply to the presence of an organism or its dead
body, excreta, or metabolic products.

• Dead insects, moult cases, or droppings, even if in some cases not

particularly harmful in themselves, can render foodstuffs unsaleable,
especially in packages in developed countries.

• Microorganisms, especially fungi and algae, can be found growing on

otherwise undamaged materials, utilizing surface dirt and detritus, but
nevertheless detracting from the value or acceptability of the material.
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DETERIORATION-Classification
FOULING OR SOILING (AESTHETIC BIODETERIORATION)
• The classic example here is the dark fungal colonies growing on damp soap and
skin residues on plastic shower curtains.

• The performance of the material is not affected, but the growth creates a
generally unacceptable appearance.
• Many fungi may also release soluble or insoluble pigments and also a range of
other metabolites which discolour on ageing.
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DETERIORATION-Classification
FOULING OR SOILING (AESTHETIC BIODETERIORATION)

• Fouling can be more serious and transcend the category of purely aesthetic
damage, in that a physical function can be impaired.

• The extra drag on ships caused by accumulations of algae, weed and

invertebrates on the hull can increase fuel consumption dramatically.

• In many cases, aesthetic biodeterioration is simply the presence of a surface

layer of microorganisms and their products.

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DETERIORATION-Classification
• These microbial layers are known as biofilms and are defined as surface
accumulations of the organic products of biological activity.

• Generally, but not always, they include living microbial cells and, in this case,
their presence may lead to the production of other classes of
biodeterioration.
• Where the cells are in such close contact with the material, rather than
merely dispersed in the surrounding environment, destructive cell activities
are localized and concentrated and the resulting effects far more damaging.

• The best studied biofilms are those on the teeth, and the results of bacterial
activities in these biofilms are well recognized by the layperson.
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DETERIORATION-Classification

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DETERIORATION-Classification

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DETERIORATION-Classification
(BIO)CHEMICAL ASSIMILATORY BIODETERIORATION
• This is probably the most easily understood form of biodeterioration.
• Quite simply, the organism is using the material as a food or energy source.
• Microbial enzymes breaking down cellulose, rats and insects eating stored
grain, and insect larvae consuming stored fruit are all examples of this type of
biodeterioration.
• The consumption of human foodstuffs by deteriogenic organisms is in the main
recognized and understood by most people, it is the variety of the microbial
diet which can cause problems.
• The fact that materials such as hydrocarbon fuels, cutting oils, adhesives,
sealants, textiles, and other ‘non-food’ items can be utilized by microorganisms
is often not realized and can lead to delays in establishing the cause of
problems.
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DETERIORATION-Classification
(BIO)CHEMICAL DISSIMILATORY BIODETERIORATION

• In this instance, a material suffers chemical damage, but not as a direct result
of the intake of nutrients by the organism.

• Many organisms excrete waste products, including pigmented or acidic

compounds, which can disfigure or damage materials.

• This type of biodeterioration often goes hand-in-hand with chemical

assimilatory biodeterioration and biofilm development, and the effects may
be difficult to differentiate.
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