www.soran.edu.iq microbiology khlood noori saeed course book 1
TRANSCRIPT
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microbiology Subject title
2(Theory) Credit hours : 2
Unit Units 2
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second stage Stage
120 minute, one sessions per week
Class schedule
20 weeks Duration 27 weeks
Assistant Lecturer Course coordinator
. .khlood saeed@soran ed.u iq
Kazem. [email protected]
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1 .Subject Description
The lectures for this course will provide you with an introduction to the generalMicrobiology and large amount of information about the outer and inner structure of the bacteria and the main difference between the gram positive bacteria and gram negative bacteria and how to control the bacterial diseases by chemical and physical materials . Finally we classified types of bacteria.
2. Require Background or ExperienceMany student know about medical microbiology and their effect on human in infections 3. Subject Objective A)Understand the fundamental concepts of microbiology and the scientific vocabulary used in this field. B) Classification of medical microorganisms according to morphological characteristics C) Knowing the common materials which are used for controlling pathogenic
bacteria and different pattern of diseases .
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.Text book)s) and Readings:
1)Prescott, L. M., Harley , J . P. and Klein, D. A.2000.Microbiology.pp.39-89 ,Wm. C. Brawn publishing, U . S . A. 2)Levinson, W. and Jawetz , E. 2000 .Sterilization and Disinfection ,In "Medical microbiology and immunology , examination and broad review , 6th ed ., pp.78-81 " McGraw – Hill medical publishing division . )3)4 5. Student Materials: 1. Textbook and References 2. Lecture Notes 3. CD and internet resources 6. Collage Facilities 1. Classroom with Whiteboard and projection facilities 2. College library 3data show
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week- 1
Historical Preview Microbiology : is defined as the science studying organisms or agents which cannot be seen by eye and must be examined by microscope (objects less than about 1 mm). Its subjects are viruses, bacteria, many algae and fungi, and protozoa.Can be divided into virology, bacteriology, algeology, mycology etc. Or on general, systematic, applied microbiology. Microbiology dawn was in the end of 19th century .In general any organism has a diameter of less than 1mm will be considered as microorganism (m-ms) . Microorganisms are necessary for the production of bread, cheese, beer, antibiotics, vaccines, vitamins, enzymes, they make possible the cycles of carbon,
oxygen, nitrogen , sulphur , and they also caused many diseases.
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Week 2
Bacteria are :The smallest organisms that all machinery required for growth and self replication.Bacterial cell have rigid cell wall surrounding the cytoplasmic membrane .The membrane provides the osmotic barrier while the wall protects the cell against osmotic rapture in dilute media and against mechanical damage .The cell wall and cell membrane together composed the cell envelope.
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week3 Capsule: Many bacteria synthesis large amount of extracellular polymer
when growing in their natural enviroments.When the polymer forms condensed layer closely surrounding the cell it is called capsule , and when it forms a loose network of fibrils extending outward from the cell it called glycocalyx , sometimes masses of polymersare formed these extracellular polymers called slime layer.Capsule contributes to the invasiveness of pathogenic bacteria in protecting them from phagocytosis.The glycocalyx plays a role in the adherence of bacteria to surfaces in their environment ,
including the cells of plant and animal hosts.
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Week 4Special components of G_ve cell wallA)-Lipoprotein:Molecule of an unusual lipoprotein cross link the outer membrane and peptidoglycan layers ,the lipoprotein contain 57 amino acids , their function is to stabilize the outer membrane and anchor it to p.g layers.B)-Outer membrane:Bilayered structure , the phospholipid of outer membrane are replaced by lipopolysaccharides.Function of outer membrane:1-prevents leakage of periplasmic space proteins.2-protects the enteric bacteria from bile salts and hydrolytic enzymes .3-contain the minor proteins.4-contain the porins that permit the passive diffusion of sugars , amino acids ,……etc.5-contains numbers of enzymes like proteases and phospholipases.
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Week 5Protoplast , Spheroplast and L-formRemoval of bacterial wall either by hydrolysis with lysozyme or treating with penicillin { prevents the synthesis of cell wall} will liberate :1-protoplast from G+ve .
2-spheroplast from G-ve If such cells are able to grow and divide they are called L-forms . L-forms are difficult to cultivate and usually require a solidified media with right osmotic strength . Some bacterial species produce L-forms spontaneously or by antibiotics.Cytoplasmic membrane: It also called cell membrane , composed of proteins and phospholipids . The c.m of prokaryotic cell is differing from those of eukaryotic cell by the absence of sterols except mycoplasma.Function of c.m :1-selective permeability and transport of solutes.2-electron transport and oxidative phosphorylation in aerobic species.3-excretion of hydrolytic exoenzyes.4-bearing the enzymes and carrier molecules that function in the biosynthesis of DNA , membrane lipids, cell wall polymers.5-bearing the receptors and other proteins.
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Week 6
Cytoplasmic Ultrastructures:*MesosomesOne or more large irregular invaginations of the plasma membrane .There are 2 types of them: a-septal mesosomes b-lateral mesosomes
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Week 7*Sheath It is a filamentous structure enables bacteria to attach to solid surfaces .These sheaths afford protection against predators and parasites.*Flagella Flagella is thread-like appendage [long filamentous appendage] extending outward from the cytoplasmic membrane , their main function is motility.flagellum composed of many subunits of protein flagellin.Flagella consist of a single very small filament made up of 3 fibers of protein flagellin .prokaryoyic flagella attached to astruture called the hook which in turn attached to the basal body.
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Week 8SporesSome bacteria are able to produce tough, dormant structures called endospores which allow them to survive when stressed.Endospores are hardy, defensive structures that enable some bacteria to survive harmful environmental conditions, such as starvation, high temperatures, desiccation, chemical disinfectants and extremes in pH. Each endospore is produced by a vegetative cell, an active bacterial cell that undergoes metabolism, divides and goes about the daily business of being alive.The ability to form endospores, a process called sporulation, Bacteria that can do this neat trick are few, but include the notable genera Clostridium and Bacillus. When a vegetative cell of an endospore-forming bacteria detects that essential nutrients are running out it begins to sporulate, a process that takes about 8-10 hours and results in the formation of one
endospore.
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Week 9
Bacterial growth curve:When bacteria are inoculated into a new culture media it shows a characteristic growth curve which has four phases : lag phase, bacteria adapt themselves to growth conditions. It is the period where the individual bacteria are maturing and not yet able to divide. During the lag phase of the bacterial growth cycle, synthesis of RNA, enzymes and other molecules occurs. log phase (sometimes called the logarithmic phase or the exponential phase) is a period characterized by cell doubling. The number of new bacteria appearing per unit time is proportional to the present population. If growth is not limited, doubling will continue at a constant rate so both the number of cells and the rate of population increase doubles with each consecutive time period. The actual rate of this growth (i.e. the slope of the line in the figure) depends upon the growth conditions and the medium is soon depleted of nutrients and enriched with wastes. The stationary phase is often due to a growth-limiting factor such as the depletion of an essential nutrient, and/or the formation of an inhibitory product such as an organic acid. Stationary phase results from a situation in which growth rate and death rate are equal. The number of new cells created is limited by the growth factor and as a result the rate of cell growth matches the rate of cell death. The result is a “smooth,” horizontal linear part of the curve during the stationary phase. At death phase,(Decline phase) bacteria die. This could be due to lack of nutrients, a temperature which is too high or low, or the wrong living conditions.
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Week 10 Factors affecting growth Microorganisms are affected by the physical nature of their environment. Environmental factors such as temperature , pH , osmotic pressure and radiation , influence the growth of microorganism. 1-TemperaturePlay a very important role in the cell cycle . The optimum temperature for enzyme activity in microorganism is depending on the ecological site of the species and the enzyme locations . Above the optimum temperature , enzymes become denatured and the rate of growth drops , producing what is called the maximum growth .Below the optimum temperature range the rate of growth decrease slowly until a point is reach , called the minimum
growth temperature , where growth ceases .
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Week
11 4-Acidity and pH: The pH of a solute describes the hydrogen ion concentration (H+) .The pH greatly influences the structure and function of proteins and enzyme and microbial growth rates . M.O vary in their pH tolerance ranges . Fungi show a wide pH range growing well over a pH range of 5-9 compared to most bacteria , which grow well over a pH range of 6-9 .In general M.O may divide into three categories: A-Alkalophiles:Grow in a pH range of 7-11 with an optimum of 10. B-Neutrophiles:Grow in a pH range of 4-9 with an optimum near neutrality.C-Acidophiles:
Live at low pH values and can be divided into facultative such as fungi .
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Week 12Nutrition of microorganisms*Carbon and energy sources for bacterial growth: All living M.O require a source of energy .M.O that use energy (light) are called phototrophs. M.O that use an organic form of carbon are called chemotrophs. M.O that oxidize inorganic compounds are called lithotrophs . M.O that use organic carbon are heterotrophs and M.O that
use CO2 as a sole source of carbon for growth are called
autotrophs.
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Week 13 Requirements of Nitrogen , Phosphorus , and Sulfur
Nitrogen: is needed for the synthesis of amino acids , purines , pyrimidines , nucleic acids , enzymes , and vitamins.Phosphorus: is present in nucleic acids , phospholipids , nucleotides like ATP , several cofactors , some proteins , and other cell components.Sulfur: is needed for the synthesis of substances like amino acids (cysteine , methionine , thiamine , biotin ) and some carbohydrates. *Growth factors:Autotroph or heterotrophy , may require small amounts of certain organic compounds for growth because they are essential substances that the organism is unable to synthesize from available nutrients . Such compounds are called growth factors . This is required in small amounts by cells because they play a specific role in biosynthesis .Growth factors are organized into three categories:A) purines and pyrimidines B) amino acids C)vitamins
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Week 14 Control of microbial growthThe rate of microbial growth and death influenced by a number of environmental parameters. Some agents destroy all forms of microbes , whereas other agents only inhibit their growth . A nutrient may be essential for growth in low concentrations ; it may be toxic at higher concentration.Control of microbial growth by antimicrobial agents: A number of inhibitory chemicals are employed for the control of microbial growth . The principal reasons for microbial control are: 1-To prevent transmission of disease and infection .2-To prevent decomposition and spoilage.3-To prevent contamination of materials used in pure culture work in
laboratories.
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Week 15Microbial and microbiostatic agents act by:1-Destruction : by a-heat (boiling , oven ) b-chemical agents( disinfectants) c-radiation (X-ray , UV ) d-Mechanical agent ( crushing , scattering by ultrasonic vibrations)2-Removal: (especially bacteria )by a-filtering b-high – speed centrifugation3-Inhibition: by a-low temperature ( refrigeration , dry ice )
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Week 16
A-Physical parameters:1-Temperature(heat): It used to sterilize materials , sterilization by heat can be divided into:a-moist heat. b-dry heat2-Filtration:It is a common technique for separating microorganismsOf different size , but it is also useful for sterilization.3- Radiation: it is used for controlling microbial growth , can be characterized as either non ionizing such as (UV) light which is absorbed by DNA at wavelength 240-280 nm. It has low penetrability and is used primarily for irradiation of air and flats, also it can be used in hospitals , or ionizing such as X-rays and gamma rays , which are characterized by their ability to impart their energy to molecules ; such as water , Ionizing radiation has been used for sterilization of pharmaceuticals and disposable medical supplies such as gloves , plastic items , catheters .4-Osmotic pressure.5-pH.6-Drying: it causes the ceases of metabolism in cells because of unavailable humidity.7-Lyophilization: ( freeze – drying ) is a more practical way of preserving M.O for storage . The principle of lyophilization is that the culture broth is dried in a glass vial while in the frozen state by removing the water through a process called sublimation .That is water is removed from the frozen state as a vapour by using ahigh vacuum system.
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Week 17B-Chemical parameters (agents )Compounds have the ability to kill or prevent growth or metabolism of M.O.Typical properties must found in these chemical agents are :1-Antimicrobial activity 2-Solubility 3-Stability 4-Non-toxic5-Homogenicity 6-Acting only with M.O 7-Capacity to penetrateInto M.O cell 8-Non-corrosive and non-staining to human.9-Have a good smell 10-Detergent capacities 11-AvailabilityFactors limited the chosen chemicals:1)Nature of the chemical material: some chemical material can be used to sterilize tools but not human skin.2)Species of M.O:it was found that bacteria E.coli is more resistant than S. aureus also it was found that spores are more resistant than vegetative cells.3)Environmental conditions: such as temperature , pH , time , chemical concentration , and the presence of organic compound in the media ,
which affect the activity of the chemicals.
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Week 18 Surface active agents: Such as soaps and detergents , they have the property of lowering surface tension , and thereby increase the wetting power of the water in which they are dissolved . They permit mechanical removal of microbes on the skin 's surface. 5-Alkylating agents ( aldehyde compounds) : The most active alkylating agents are formaldehyde , glutaraldehyde , β – propiolactone , and ethylene oxide. Formaldehyde : is mainly used as a preservation and because of its irritation of tissue and odor it is seldom used as a disinfectant .Formalin: is a 37% solution of formaldehyde gas and is used for the preservation and fixation on tissue it combine with proteins and nucleic acids causing death to cell. Glutaraldehyde: it is active against bacteria and viruses in 2% solution , but spores are destroyed only after 10 h. β-propiolactone :is used in the gaseous phase to sterilize liquids . It is effective against bacteria , fungi , viruses and spores , but it use has been restricted because of its
potential carcinogenic properties.
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Week 19 Antibiotics Materials produced by microorganisms metabolism , it has low molecular weight , have the ability to inhibit another microorganisms growth when it used in little concentrations.In 1877 , Pasteur and Gobert noticed that bacteria P.aeruginosa produce material called later pyocyanin , which inhibit Bacillus anthracis growth .In 1929 Fleming noticed an inhibition zone around Penicillium notatum colonies ,which contaminate petri dish
cultivated with Staphylococcus.
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Week 201-Inhibition of cell membrane function: they change permeability of the microbial cell .2-Inhibition of cell wall synthesis : 3-Inhibition of nucleic acids synthesis:
4-Inhibition of protein synthesis :