mikro sbi 2
TRANSCRIPT
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Microbiology
UNIT I : Scope and History
UNIT II : Microscopy and Staining
UNIT III : Growth and Culturing UNIT IV : Sterilization and Disinfection
UNIT V : The Bacteria
UNIT VI : Viruses
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Scope and History of Microbiology
Why Study Microbiology
The Microbes
Disease Causes by Microorganism History Roots
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SCOPE AND HITORY OF
MICRIBIOLOGY
Why Study Microbiology
Microorganisms are part of the humanenvironment and are there fore important to
human health and activities.
The study of microorganisms provides insight
into life processes in all forms of life.
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Scope of Microbiology
The Microbes
Microbiology is the study of all
microorganisms (microbes) in the
microscopic range.
This include :
bacteria,algae,fungi,viruses,and protozoa
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Diseases caused by
Microorganisme
Bacterial diseases:
Syphilis,tetanus,trachoma,meningitis,etc
Viral diseases : AID,Hepatitis,yellow
fever,etc
Protozoan disease : Malaria,Amebiasis
Helminth diseases : Trichinosis.
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The germ theory of disease
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Pasteur further contributions
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Kochs Contributions
Kochs Postulates:
1.The specific causative agent must be found inevery case of the disease.
2.The disease organism must be isolated in pureculture
3.Inoculation of a sample of the culture into ahealthy,susceptible animal must produce the
same disease.4.The disease organisms must be recovered from
the inoculated animal.
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II.Microscopy and Staining
Principles of microscopy
Light Microscopy
Electron Microscopy
Principles of staining
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MICROSCOPY
The technology of making very small
things in visible to the human eye.
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Comparison of Types of
Microscopy
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Metric Unit
Centimeter =0,01 m
Millimeter =0,001 m
Micrometer =0,000001 m Nanometer =0,000.000.001 m
Angstrom = 0,000.000.000.1 m
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III. Growth and Culturing of
Bacteria
Culture Media
Growth and Cell division
Phases of Growth Measuring Bacterial Growth
Factor Affecting Bacterial Growth
Culturing Bacteria
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CULTURE MEDIA
In nature, microorganims
are growth on nature media
or nutrients available in
water,soil,and living or dead
organic material.
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In The Laboratory
Microorganisms are grown in synthetic
media :
1.Defined synthetic media: consist of
known quantities of spesific nutrien
2. Complex media : consist of nutrients ofreasonably well known composition that
vary in composition from batch to batch.
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Commonly Used Media
Most routine laboratory cultures
make us of peptones,or fish
proteins. Other substances suchas yeast extract,serum, whole
blood, etc.
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Diasnostic Media.
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GROWTH AND CULTURING
1. Microbial growth can be defined as the
orderly increase in quantity of all cell
componen and in the number of cells of an
organims
2.Because of limited in crease in cell size
and the frequency of cell division, growth
in microorganism is measured by increasein cells number.
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Division Cell
Most cell division in bacteria occur bybinary fission,in which the nuclear bodydivides and the cell form are transverse
septum that separates the original cell intotwo cells.
Yeast cell and same bacteria divide bybudding, in which a small, new celldevelops from the surface of an existingcell.
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Growth and Cell Division
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Phases of Growth
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Phases of growth
Lag phase : Not increasing in cell number, metabolicallyactive.
Log phase : devide at exponential or logaritmic, rate andwith a constant generation time.these properties can beused to calculate both the number of generation time
and the generation. Stationary phase : The number of new cell produced
equals the number of cell dying.The medium containslimited nutriens and contains toxic quantities of wastematerials.
Decline phase ; death phase : many cells lose theirability to devide and eventually die. A logaritmicdecrease in the number of cell results.
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Measuring bacterial growth
Growth can be measured by serial dilution.
Growth also can be measure by direct
microscopic count, the most probable
number technique,filtration,observing or
measuring products of metabolism, and
obtaining the dry weight of cell.
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The technikque of serial dilution
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Methods of obtaining cultures
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The streak plate method.
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Spread plate method
Put 0,1 ml desired concentration(reached),
pour into surface of pre-poured agar then
spread with abent rod,next is
incubated.Bacterial colonies appear onlyon surface.
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pour plate method
1 ml of dilution (concentration reached) is
mixed with 9 ml of melted agar. Mix
throughly and pour entire petri dish. Cool
to hardness and incubate. Same coloniesappear on surface,many are bellow
surface.
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The streak plate method
A drop or bit of culture on a wire
inoculating loop is lightly streaked across
the top of the agar in region1.The loop is
flamed,the plate is rotated,and a feworganism are picked up from region 1 and
streaked out into region 2,The loop is
flames again and the process is repeatedin region 3.
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Principles of staining
A stain or dye is a molecule that can bind
to a structure and give it color.
Most microbial stain are cationic (positively
charged),or basic, dyes,such as
methylene blue.
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Comparison of Staining techniques
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The Gram Stain
The gram stain, was devised by Hans
christian Gram, in 1884.
The gram stain probabily the most
frequently used deferential stain.
Gram was testing new methods of staining
biopsy and autopsy material.
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Steps in gram staining
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Factors affecting bacterial growth.
1. Physical factor: pH, Temperature,
Oxygen
2. Nutritional factor :carbon sources.
Nitrogen sources, vitamin.
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Physical factors
A.Optimum pH
Bacteria are clasified as
1. Acidophiles :pH below 5,4. Exm:Lactobacilus
2. Neutrophiles (pH 5,4 -8,5). Ex : Bacteria
that causes disease in human.
3.Alkaliphiles : pH 7,0-11,5. Ex
:Agrobacterium,alcaligenes faecalis.
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B.Temperature
Bacteria are clasified as :
1.Psychrophiles( 150C-200C )
a. Obligate psychrophiles (cannot growabove 200C ).Ex.Bacillus globisporus.
b.Facultative psychophiles (grow best
below 200
C). Ex.Xanthomonas sp
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2. Mesophiles (250C 400C)
3.Thermophiles(500C -600C) Ex. Bacillus
stearothermophilus.
C.Oxygen
a.aerobes (require oxygen to grow).
Ex:pseudomonas
b.anaerobes(do not requere it).
Ex:Bacteroides.
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Nutritional factors
Carbon sourcesAutotrophs : us CO2 as carbon source
Heterotroph :require glocose or organic
carbon source
.Nitrogen sources : sulfur,phosphorus,Iron,etc.
.Sulfur and phosphorus :Amino acid,organic
phosphate .
.Vitamin :B12, K (small amount or as a coenzyme.
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Sterilization and Disinfection
1.Principles of Sterilization and
Disinfection
2.Chemical antimicrobial agents
a.potency of chemical agent
b.Mechanisms of action
c.specific chemical agent
3. Physical antimicrobial agents.
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Sterilization
Refers to the killing or
removal of all organisms
in any material or on
object.
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Disinfection
Refers to the reduction in
numbers of pathogenic
organism on obyects or
in materials so that theorganisms no longer
pose a disease threat
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TERM OF RELATED TO STERILIZATION
AND DISINFECTION
ANTISEPTIC : A chemical agent that can
safely be used externally on living tissue to
destroy microorganisms or to inhibit their
growth
Disinfectant : A chemical agent used on
inanimate obyects to destroy
migroorganisms . Most disinfectant do notkill spores.
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SANITIZER :A chemical agent typically
used on food-handling equipment and
eating utensils to reduse bacterial
numbers so as to meet public healthstandards. Sanitization may simply refer to
thorough washing with only soap or
detergent. Bactericide : An agent that kills bacteria.
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POTENCY OF CHEMICAL AGENT
The potency of chemical agent is affected by
time,
temperature,
pH,
Concentration of the agent.
M h i f ti f h i l
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Mechanisms of action of chemical
agent
Action of chemical agent antimicrobial agent canbe grouped according to their effects on protein,cell membranes and other cell components.
Reactions that alter protein include hydrolysis,oxidation,and attachment of atoms or chemicalgeoups to protein molecules. Such reactiondenature protein, rendering them nonfungtional.
Reactions of other chemical agents damagenucleic acids and energy-producing systems.Demage to nucleic acids is an important meansof inactivating viruses.
SPECIFIC CHEMICAL
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SPECIFIC CHEMICAL
ANTIMICROBIAL AGENTS
Soaps and detergents aid in the removal
of microbes,oils,and dirt but do not
sterilize.
Among the agent containing heavymetals, silver nitrate is used to kill
gonococci, and mercury containing
compounds are used to disinfectinstrument and skin.
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Acid are commonly used as food
preservatives, alkali in soap helps destroy
microorganisms.
Alkohols are used to disinfectants
Among the agents containing halogens,
chlorine is use to kill pathogens in water,
and iodine is major ingredient in severalskin disinfectants.
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Phenol derivatives can be used on skin,
instruments,dishes, and furniture, and to
destroy discarded cultures they work well
in the presence of organic materials.
Oxidizing agents are particularly useful in
disinfecting puncture wounds.
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Alkylating agents can be used to disinfect
or sterilize a variety of materials, but all
are carcinogens.
Same dyes, plant oils, sulfur containing
subtances and nitrates can be used as
disinfectans or food preservatives.
PHYSICAL ANTIMICROBIAL
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PHYSICAL ANTIMICROBIAL
AGENTS
Heat destroys microorganisms by
denaturing protein, melting
lipids,and when open flame isused,by incineration.
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Dry heat,Moist heat,Pasteurization
Dry heat is used to sterilize metal obyects and
glassware.
Flame is used to sterilize inoculating loops and
the mouths of culture tubes. Autoclave uses moist heat underpresure, is a
common instrument for sterilization and is very
efective when proper procedures are followed.
Pasteurization kill most patogens milk,does not
sterilize.
Refrigeration freezing drying and
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Refrigeration, freezing,drying,and
Freeze-drying.
Can be used to retard the growth
of microorganisms.
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Radiation
Used to control microorganisms
includes ultraviolet light, ionizing
radiation,and some timesmicrowaves and strong sunlight.
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Sonic and Ultra sonic waves
Can kill microorganisms but are
used mostly for sonication,the
disruption of cell by sound waves
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Filtration
Can be used to sterilize
subtances that are destroyed by
heat, to separate viruses, and tocollect microorganisms from air
and water samples.
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Osmotic pressure
High concentrations of sugar or
salt create osmotic presure that
plasmolisis of cell and preventsgrowth of microorganisms in
gightly sweetened or salted foods.
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