Chair of Microbiology, Virology, and Immunology

THE HISTORY OF MICROBIOLOGY. THE HISTORY OF MICROBIOLOGY. CLASSIFICATION AND CLASSIFICATION AND SSTRUCTURE OF TRUCTURE OF

MICROORGANISMS.MICROORGANISMS.

Lecturer As. O. B Kuchmak

Lecture scheduleLecture schedule

1.1. History of MicrobiologyHistory of Microbiology..2.2. Classification of bacteriaClassification of bacteria. . 3.3. Structure of bacterialStructure of bacterial cellcell4.4. The physiology of microorganisms.The physiology of microorganisms.

Growth, reproduction and Growth, reproduction and respiration of bacteria.respiration of bacteria.

Why Study Microbiology?Why Study Microbiology?

PharmaceuticalsPharmaceuticals Vaccines/AntibioticsVaccines/Antibiotics BiotechnologyBiotechnology

BioremediationBioremediation

PathogenicityPathogenicity

Fundamental BiologyFundamental Biology

MicrobiologyMicrobiology The study of microorganismsThe study of microorganisms

MicroorganismsMicroorganisms living living things too small to be seen things too small to be seen with the unaided eyewith the unaided eye

Microorganisms = MicrobesMicroorganisms = Microbes

MicroorganismsMicroorganismsDivided into six groupsDivided into six groups BacteriaBacteria ArchaeArchae AlgaeAlgae FungiFungi ProtozoaProtozoa VirusesViruses

History of MicrobiologyHistory of Microbiology

Microbes discovered >300yrsMicrobes discovered >300yrsKnown to man during the mid Known to man during the mid

1800s1800sPeriod of progress began & Period of progress began &

continues to the presentcontinues to the present

Periods Periods of microbiology developmentof microbiology development

MorphologicMorphologic PhysiologicPhysiologic ProphylacticProphylactic

Morphological period Morphological period inin microbiology history microbiology history (XVII middle of age).(XVII middle of age).

It is also called micrographycal period, as the It is also called micrographycal period, as the study of microorganism came only to study of microorganism came only to description of their dimensions and forms. description of their dimensions and forms. Biological properties and their significances for Biological properties and their significances for man still a long time remained man still a long time remained incomprehensible.incomprehensible.

Experimental phaseExperimental phase

LeeuwenhoekLeeuwenhoek PasteurPasteur KochKoch Lister Lister

Before 17th century, study of microbiology was Before 17th century, study of microbiology was hampered by the lack of appropriate tools to hampered by the lack of appropriate tools to observe microbes.observe microbes.

Robert HookeRobert Hooke: In 1665 built a compound : In 1665 built a compound light microscope and used it to observe thin light microscope and used it to observe thin slices of cork. Coined the word slices of cork. Coined the word cellcell..

Anton van Leeuwenhoeck:Anton van Leeuwenhoeck: In 1673 was the In 1673 was the first person to observe live microorganisms first person to observe live microorganisms which he called “which he called “animalculesanimalcules” (bacteria, ” (bacteria, protozoa), using single-lens microscopes that he protozoa), using single-lens microscopes that he designed. He observed 50,000 different designed. He observed 50,000 different specimens, reported findings to the Royal specimens, reported findings to the Royal Society of LondonSociety of London

Edward JennerEdward Jenner ( 1796) ( 1796) Smallpox Smallpox immunity / Vaccineimmunity / Vaccine

Pasteurization:Pasteurization: Developed a process in Developed a process in which liquids are heated (at 65which liquids are heated (at 65ooC) to kill C) to kill most bacteria responsible for spoilage.most bacteria responsible for spoilage.

Disease CausesDisease Causes: Identified three different : Identified three different microbes that caused silkworm diseases.microbes that caused silkworm diseases.

Vaccine: Vaccine: Developed a vaccine for rabies Developed a vaccine for rabies from dried spinal cords of infected rabbits.from dried spinal cords of infected rabbits.

Directed Pasteur Institute until his death in Directed Pasteur Institute until his death in 1895.1895.

Pasteur’s Contributions:Pasteur’s Contributions:

French Chemist Pasteur French Chemist Pasteur (1861)(1861)

Joseph Lister (1859):Joseph Lister (1859): Used Used disinfectant to treat surgical wounds, disinfectant to treat surgical wounds, greatly reducing infection rates. greatly reducing infection rates. Considered the father of antiseptic Considered the father of antiseptic surgery.surgery.

Robert Koch (1876):Robert Koch (1876): First person proved that microorganisms First person proved that microorganisms

caused diseasescaused diseases Only specific microorganisms caused specific Only specific microorganisms caused specific

diseasesdiseases Studied anthrax Studied anthrax affects cattle & humans affects cattle & humans Proved that Proved that Bacillus anthracisBacillus anthracis causes anthrax causes anthrax

in cattle.in cattle. Later identified bacterium that causes Later identified bacterium that causes

tuberculosis.tuberculosis.

Study of virusesStudy of viruses Iwanoski (1892)Iwanoski (1892) studying studying

diseases of tobacco plantsdiseases of tobacco plants Discovered TMVDiscovered TMV Filterable virusesFilterable viruses

PProphylactic periodrophylactic periodAfter 1914After 1914

Classic Metchnikov's Classic Metchnikov's researches definedresearches defined a a prophylactic periodprophylactic period inin microbiology history. microbiology history.

The Patriarch of world and Ukrainian microbiology - I. Metchnikov

Paul Ehrlich (1910Paul Ehrlich (1910): Search for “): Search for “magic bulletmagic bullet”.”. Discovered salvarsan, an arsenic derivative, was Discovered salvarsan, an arsenic derivative, was

effective against syphilis. (effective against syphilis. (11stst synthetic drug to synthetic drug to come in to widespread use)come in to widespread use)

Alexander Fleming (1928)Alexander Fleming (1928): Discovered that : Discovered that penicillin produced by the mold penicillin produced by the mold Penicillium notatumPenicillium notatum was able to prevent microbial growth.was able to prevent microbial growth. Penicillin Penicillin came into use 10 yrs latercame into use 10 yrs later

-By the 1940s known as the -By the 1940s known as the “wonder “wonder drug”drug”

Rene Dubos (1939): Rene Dubos (1939): Discovered two antibiotics Discovered two antibiotics (gramidin and tyrocidine) produced by bacterium (gramidin and tyrocidine) produced by bacterium ((Bacillus brevisBacillus brevis).).

Bergey's Manual

of Determinative Bacteriology – the "bible" of bacterial taxonomy.

There are such levels of microorganisms’ organization: Species – Genus – Family – Class – Division – Kingdom

Classifications system.

35 of the major groups of bacteria are distinguished primarily on morphological characteristics, namely: cell shapes (rods, cocci, curved, or filament forming); spore production; staining reactions; motility.

Other groups are defined based on their metabolism, or combinations of morphological and physiological characteristics.

Some of the Major Groups of Bacteria in Bergey's Manual

SpirochetesSpirochetes

Very slender rods that are helically Very slender rods that are helically coiled around a central axial filament; coiled around a central axial filament; includes the bacteria that cause includes the bacteria that cause syphilis and Lyme diseasesyphilis and Lyme disease

Gram-positive Gram-positive coccicocci

Bacteria that have a cell wall structure Bacteria that have a cell wall structure that results in their staining blue-that results in their staining blue-purple by the Gram stain procedure purple by the Gram stain procedure and that are spherical; include the and that are spherical; include the streptococci and staphylococci streptococci and staphylococci

Endospore-Endospore-forming rods forming rods

and cocciand cocci

Bacteria that form heat-resistant Bacteria that form heat-resistant bodies called endospores within their bodies called endospores within their cells; include the bacteria that cause cells; include the bacteria that cause gas gangrene, botulism, tetanus, and gas gangrene, botulism, tetanus, and anthraxanthrax

Small, single-celled (Small, single-celled (unicellularunicellular) organisms.) organisms. Procaryotes:Procaryotes: “Before nucleus”. “Before nucleus”.

LackLack the following structures: the following structures: Nuclear membrane around DNANuclear membrane around DNA Membrane bound organellesMembrane bound organelles

MitochondriaMitochondria ChloroplastsChloroplasts Golgi apparatusGolgi apparatus Endoplasmic reticulumEndoplasmic reticulum LysosomesLysosomes

Bacteria (Sing. Bacterium)Bacteria (Sing. Bacterium)

PropertyProperty ProkaryoticProkaryotic EukaryoticEukaryotic

1- Size1- Size 0.5 - 10μm0.5 - 10μm 5-100μm5-100μm

2- Cell Wall2- Cell Wall Present in all bacteria Present in all bacteria Except in MycoplasmaExcept in Mycoplasma

Present in Fungi & AlgaePresent in Fungi & Algae

3- Cytoplasmic 3- Cytoplasmic MembraneMembrane

No Sterol Except in No Sterol Except in MycoplasmaMycoplasma

Has sterolsHas sterols

4- Nuclear 4- Nuclear MembraneMembrane

AbsentAbsent PresentPresent

5- Nucleus5- Nucleus AbsentAbsent PresentPresent

6- Chromosome6- Chromosome Single chromosomSingle chromosom[not associtred with [not associtred with

proteinprotein

More than oneMore than one[associated with histone][associated with histone]

7- Mitochondria7- Mitochondria AbsentAbsent PresentPresent

8- Ribosome8- Ribosome Sedimentation coefficientSedimentation coefficient70S70S

Sedimentation coefficientSedimentation coefficient80S80S

9- Reproduction9- Reproduction Asexual (binary fusion)Asexual (binary fusion) Sexual & AsexualSexual & Asexual

10- Example10- Example Bacteria, Chlamydia, Bacteria, Chlamydia, RickettsiaeRickettsiae

Fungi & ProtozoaFungi & Protozoa

Bacterial Identification and Bacterial Identification and ClassificationClassification

Shape - cocci, bacilli, spiralShape - cocci, bacilli, spiral Arrangement - single, pairs, chains, Arrangement - single, pairs, chains,

clustersclusters Size Size Gram-positive vs. Gram-negativeGram-positive vs. Gram-negative Aerobic vs. anaerobicAerobic vs. anaerobic Physical/structural characteristicsPhysical/structural characteristics Biochemical characteristicsBiochemical characteristics DNA analysisDNA analysis

The Dimension of BacteriaThe Dimension of Bacteria The Dimension of BacteriaThe Dimension of Bacteria

Relative size of a bacterial cell compared to other cells including viruses.

Gross morphology of bacteriaGross morphology of bacteria Size - 1 to 10 mm - aids in identificationSize - 1 to 10 mm - aids in identification ShapeShape

Coccus - round

Bacillus - rod- Fusiform, coccobacilli

Spirillum - corkscrew

- Flexible, undulating - spirochetes- Curved - vibrios

Cocci groupingsCocci groupings

Coccus

Diplococcus

Streptococcus

Tetrad

Sarcinae

Staphylococcus

Chains of cocciChains of cocci

Streptococcus pyogenes

Clusters of cocciClusters of cocci

Staphylococcus aureus Sputum smear

Bacillus shaped bacteriaBacillus shaped bacteria

Pseudomonas aeruginosaEscherichia coli

Bacillus shaped bacteriaBacillus shaped bacteria

Fusobacterium

Bacillus chainsBacillus chains

Bacillus anthracis

Palisades arrangementPalisades arrangement

Corynebacterium diphtheriae

Curved bacteriaCurved bacteria

Vibrio cholerae

Campylobacter

Curved bacteriaCurved bacteria

Borrelia burgdorferi

Spirilla

Bacterial surface structuresBacterial surface structures

Cell EnvelopeCell EnvelopeCell EnvelopeCell Envelope

Cytoplasmic membrane Cytoplasmic membrane Cell wallCell wall

Cell wall-less bacteriaCell wall-less bacteria No peptidoglycan layerNo peptidoglycan layer Cell membrane contains sterols for Cell membrane contains sterols for

stabilitystabilityMycoplasma pneumoniae

Cytoplasmic MembraneCytoplasmic MembraneCytoplasmic MembraneCytoplasmic Membrane

Phospholipid bilayerPhospholipid bilayer ““Fluid mosaic” modelFluid mosaic” model

Embedded proteins for active transportEmbedded proteins for active transport

Enzymes for energy generationEnzymes for energy generation Photosynthetic pigmentsPhotosynthetic pigments

Cell membraneCell membrane

PeripheralMembraneProtein

IntegralMembraneProtein

PeripheralMembraneProtein

Phospholipid

Selective permeability to different Selective permeability to different molecules. molecules.

Active transport aided by permease.Active transport aided by permease. Play a role in DNA replication.Play a role in DNA replication. Cell wall biosynthesis.Cell wall biosynthesis. Mesosomes ----- cell division.Mesosomes ----- cell division.

Function of Cytoplasmic MembraneFunction of Cytoplasmic Membrane

Cell wallCell wall Two major groups of bacteria based Two major groups of bacteria based

on structure of cell wallon structure of cell wall Gram positiveGram positive

Thick peptidoglycan layerThick peptidoglycan layer Gram negativeGram negative

Thin peptidoglycan layerThin peptidoglycan layer Outer membrane containing LPSOuter membrane containing LPS

Gram stain is crucial first step toward Gram stain is crucial first step toward identificationidentification

Peptidoglycan (cell wall)Peptidoglycan (cell wall)

Cell WallCell Wall Cell WallCell Wall Gram positive cell wallGram positive cell wall

Thick peptidoglycan (PG) layerThick peptidoglycan (PG) layer Acidic polysaccharidesAcidic polysaccharides Teichoic acid and lipoteichoic acidTeichoic acid and lipoteichoic acid

Gram-negative cell wallGram-negative cell wall Thin peptidoglycan (PG) layerThin peptidoglycan (PG) layer Lipopolysaccharide layerLipopolysaccharide layer PorinsPorins Periplasmic spacePeriplasmic space

Gram-positive cell envelopeGram-positive cell envelope

Gram-negative cell Gram-negative cell envelopeenvelope

Cell Wall StructuresCell Wall Structures Cell Wall StructuresCell Wall Structures

Structures associated with gram-positive and gram-negative cell walls.

Maintenance of the shape (due to rigidity of Maintenance of the shape (due to rigidity of peptidoglycan).peptidoglycan).

Protects the cytoplasmic membrane cell Protects the cytoplasmic membrane cell contentscontents RigidityRigidity Cell wall is osmotically insensitiveCell wall is osmotically insensitive

Hypotonic solution – cell burst.Hypotonic solution – cell burst. Hypertonic solution – cell shrank.Hypertonic solution – cell shrank. Isotonic solution – bacteria is life.Isotonic solution – bacteria is life.

Function of Cell WallFunction of Cell Wall

L FormsL FormsL FormsL Forms

Mutations can cause some bacteria to lose the ability to synthesize the cell wall and are called L forms.

CapsulesCapsules

are important forare important for Adhesion Adhesion (Associated with virulence in bacteria) Avoidance of immune responseAvoidance of immune response

(Protects bacteria from phagocytic cells)(Protects bacteria from phagocytic cells) Protection from dehydrationProtection from dehydration

CapsuleCapsule

Klebsiella pneumoniaeBacillus anthracis

Streptococcus pneumoniae

External structuresExternal structures Pili (Pili (Fimbriae) play roles inplay roles in

AdhesionAdhesion Exchange of genetic materialExchange of genetic material Avoidance of immune responseAvoidance of immune response

FlagellaFlagella are important for are important for Motility (dispersal)Motility (dispersal) Antigenic determinant (Antigenic determinant (“H” antigens)

Number and location species specificNumber and location species specific

Pili and flagellaPili and flagella

Salmonella

Fimbriae are smaller than flagella and are important for attachment.

Pili Pili Pili Pili

Pili enable conjugation to occur, which is the transfer of DNA from one bacterial cell to another (“mating”).

Flagellar StructureFlagellar StructureFlagellar StructureFlagellar Structure

Three components of a flagellum: filament, hook and basal body

It composed of protein subunits calledIt composed of protein subunits called flagellinflagellin..

Flagellar ArrangementFlagellar ArrangementFlagellar ArrangementFlagellar Arrangement

(a) Monotrichous (b) Lophotrichous(c) Amphitrichous (d) Peritrichous

Bacterial MotilityBacterial MotilityBacterial MotilityBacterial Motility

The rotation of the flagella enables bacteria to be motile.

CytoplasmCytoplasm Genome Genome Inclusion bodiesInclusion bodies EndosporeEndospore

Internal StructuresInternal Structures

CytoplasmCytoplasmCytoplasmCytoplasm

Gelatinous solution containing Gelatinous solution containing

water, nutrients, proteins, and water, nutrients, proteins, and

genetic materialgenetic material

Site for cell metabolism Site for cell metabolism

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Chemical Analysis of Microbial Chemical Analysis of Microbial CytoplasmCytoplasm

70% water70% water ProteinsProteins 96% of cell is composed of 6 elements:96% of cell is composed of 6 elements:

carboncarbon hydrogenhydrogen oxygenoxygen phosphorousphosphorous sulfursulfur nitrogennitrogen

Bacterial GenomeBacterial Genome Bacterial GenomeBacterial Genome

Most bacteria contain a single circular double strand of DNA called a nucleoid.

Prokaryotic RibosomeProkaryotic RibosomeProkaryotic RibosomeProkaryotic Ribosome

A ribosome is a combination of RNA and protein, and is the site for protein synthesis

Composed of large (50S) and small (30S) subunits

S = Svedverg unit, measures molecular size

Inclusion BodiesInclusion BodiesInclusion BodiesInclusion Bodies

Inclusion bodies enable a cell to store nutrients and to survive in nutrient depleted environments

Some bacteria, notably those of the Some bacteria, notably those of the

genera Bacillus and Clostridium, develop genera Bacillus and Clostridium, develop

a highly resistant resting phase or a highly resistant resting phase or

endospore that does not grow or endospore that does not grow or

reproduce and exhibit absolute dormancy reproduce and exhibit absolute dormancy

(not detectable metabolism). (not detectable metabolism).

Bacterial SporesBacterial Spores

EndosporesEndospores

Bacillus anthracis

Vegatitive formVegatitive form The bacteria actively growing, non spore The bacteria actively growing, non spore

stage of a bacterium.stage of a bacterium. Sporulation:Sporulation:

Formed on exposure to unfavorable Formed on exposure to unfavorable condition,E.g., condition,E.g.,

Nutrient depletion Nutrient depletion ChangesChanges

Moisture,Moisture, Temperature, Temperature, pH orpH or Oxygen tensionOxygen tension

Spore requires 10-15 hours to form.Spore requires 10-15 hours to form.

Endospore formationEndospore formation

GerminationGermination Mature endoscope are metabolically inertMature endoscope are metabolically inert Changes in the environmentChanges in the environment

Retuning to vegetative state within 15 Retuning to vegetative state within 15 minutes.minutes.

In the process of germination the spores In the process of germination the spores absorb water and swell, the protective absorb water and swell, the protective coat disintegrates and a single vegatitive coat disintegrates and a single vegatitive cell emerges.cell emerges.