Introduction and history of microbiology Bacterial morphology

1. INTRODUCTION TO
MICROBIOLOGY
Maria Gelica Dumlao
Kristine Jane
Turqueza
CSU-CM 2B

2. MICROBIOLOG
Y
• Study of
microorganisms

3. MICROORGANISM
S
• Microscopic organisms
existing as single cells
or as single cell clusters

4. Examples:
Viruses- incomplete
microorganisms without
nucleoids
Prions- protein fragments
which may be pathologic
Bacteria- prokaryotic
Fungi, protozoans, and
helminths

5. •a qualitative trait
referring to inherent
capacity of a
microorganism to cause
disease mediated by
specific virulence factors.
Pathogenecity
•Severity of the disease in
infected host
Virulence

6. VIRUSES
Nucleic acid (either DNA or RNA, but
never both; thus they are classified as
to DNA viruses and RNA viruses)
wrapped in a protein coat
In their own are incapable of
metabolism, need a host cell for
replication
Infects and replicates within cells,
causing damage to the host cells

7. PRIONS
Protein particles that are
proteinacious (able to digest
proteins) and infectious
Nearest in structure to viruses but
does not contain nucleic acids

8. BACTERIA
Single celled organisms of diverse
shapes and sizes, diverse nutrient
requirements and diverse
pathogenicity
Common trait: Lacks a nuclear
membrane and a true nucleus
(prokaryotic)
Can have both DNA & RNA which is
packaged in a structure known as
nucleoid
Capable of metabolism

9. PROTOZOA
Single celled eukaryotes (True
cells)
Belong to an exclusive kingdom
(Kingdom Protista)
MOTILE AND FAIRLY LARGE
Ex. Amoeba, malarial parasites

10. HELMINTHS
Complex multicellular
organisms, most of which are
already visible to the naked eye
Eukaryotic
Ex. Ascaris lumbricoides

11. HISTORY

12. LUCRETIUS (98-55 BC) AND
GIROLAMO FRACASTORO (1478-
1553)
- Roman philosophers who
suggested that diseases were
caused by “invisible living
creatures”

13. ARISTOTLE (384-322 BC)
-He mentioned that
simple invertebrates
could arise from
spontaneous generation

14. FRANCESCO REDI (1626-1697)
-in 1668, he demonstrated that
maggots do not arise
spontaneously from decaying
meat

15. JOHN NEEDHAM (1748)
-He proposed that organic matter
possessed a “vital force” that could give
rise to life.

16. LAZZARO SPALLANZANI
(1729-1799)
-he proposed that air carried
microorganisms to the culture
medium and that might be the
reason for the growth of
organisms present already in
the medium

17. LAURENT LAVOISIER (1743-1794)
-he showed the importance
of oxygen to life
RUDOLF VIRCHOW (1858)
-challenged spontaneous
generation with the concept
of biogenesis

18. LOUIS PASTEUR (1822-1895)
-resolved the issue of spontaneous
generation
-Stated that microorganisms are
indeed present in the air and can
contaminate seemingly sterile
solution, however, the air itself
does not create microbes

19. FERDINAND COHN (1828-1898)
-Demonstrated that no matter
how long some flasks were
boiled they always
-produced certain growth
(heat resistant bacterial spore)

20. CHARLES CHAMBERLAND
(1851-1908)
-created a porcelain
bacterial filter (1884) and
developed anthrax vaccine
together with Pasteur

21. IGNATZ SEMMELWEIS
he demonstrated that
routine handwashing can
prevent spread of
infection

22. JOSEPH LISTER (1827-1912)
-developed the antiseptic system of
surgery
-introduced handwashing to British
surgery and the uses of phenol as
an antimicrobial agent for surgical
wound dressing

23. IMPORTANT EVENTS in the
development of
microbiology

25. 1676- Anton van Leeuwenhoek discovered
animalcules
-first true microbiologist
-first person to observe and describe
microorganisms accurately
-Father of Protozoology and Bacteriology
*He used his self-made single lens
microscope with 50-300x magnification to
study protozoans and bacteria

26. 1786- OTTO MULLER
PRODUCED THE FIRST
CLASSIFICATION OF
BACTERIA
1798- JENNER INTRODUCED COWPOX
VACCINATION FOR SMALL POX
1838-1839- SCHWANN AND SCHLEIDEN’S
CELL THEORY

27. 1858- VIRCHOW STATED THE
THEORY OF BIOGENESIS
1867- LISTER PUBLISHED HIS WORK
ON ANTISEPTIC SURGERY
1881- KOCH CULTURED BACTERIA
ON GELATIN

28. 1884
• First publication of Koch’s
postulates
• Metchnikoff described
phagocytosis
• autoclave was developed by
Charles chamberland
• Hans Christian Gram developed
gram stain

29. 1885- PASTEUR DEVELOPED RABIES
VACCINE
1886- RICHARD PETRI DEVELOPED PETRI
DISH (PLATE)
1890- VON BEHRING PREPARED
ANTITOXINS FOR DIPHTHERIA AND
TETANUS

30. 1896- ROSS SHOWED THAT MALARIA
PARASITE IS CARRIED BY THE
MOSQUITOES
1900- REED PROVED THAT YELLOW
FEVER IS TRANSMITTED BY MOSQUITOES
1906- SCHAUDINN AND HOFFMAN
SHOWED TREPONEMA PALLIDUM CAUSES
SYPHILIS

31. 1910- EHRLICH DEVELOPED
CHEMOTHERAPEUTIC AGENT
FOR SYPHILIS
1933- RUSKA DEVELOPED FIRST
TRANSMISSION ELECTRON MICROSCOPE
(TEM)
1937- CHATTON DIVIDED LIVING
ORGANISMS INTO PROKARYOTES AND
EUKARYOTES

32. 1944- WAKSMAN DISCOVERED
STREPTOMYCIN
1945- FLEMING AND CHAIN DISCOVERED
PENICILLIN AND ITS THERAPEUTIC USE
1951- THEILER DEVELOPED YELLOW
FEVER VACCINE

33. 1953- DEVELOPMENT OF PHASE
CONTRAST MICROSCOPE; CRICK
AND WATSON DISCOVERED THE
STRUCTURE OF DNA
1954- YALOW DEVELOPED THE
RADIOIMMUNOASSAY TECHNIQUE (RIA)

34. 1975- LYME DISEASE DISCOVERED
BY WILLY BURGDORFER
1976- RECOGNITION OF
ARCHEOBACTERIAAS A DISTINCT
MICROBIAL GROUP
1980- DEVELOPMENT OF SCANNING
TUNNELING MICROSCOPE (STM)

35. 1983-1984- GALLO AND
MONTAGNIER IDENTIFIED AND
ISOLATED HIV; MULLIS
DEVELOPED PCR
1986- FIRST HEPATITIS B VACCINE BY
GENETIC ENGINEERING APPROVED FOR
HUMAN USE
1995- CHICKEN POX VACCINE APPROVED

36. CLASSIFICATION OF
BACTERIA
• Used to describe the diversity of bacterial
species, and appreciate the similarities and
differences between them
• Ex. Staphylococcus aureus and Streptococcus
pyogenes both appear as short and stout
(round) bacteria but S. aureus appear as a
bunch of grapes microscopically, while S.
pyogenes exists in chains.

37. TAXONOMY
-the vocabulary of medical
microbiology
CARL VON LINNE
Father of Taxonomy

38. 3 INTERRELATED AREAS OF
BACTERIAL TAXONOMY
2.) Nomenclature
1.) Classification
3.) Identification

39. CLASSIFICATION
- Organization of microorganisms that
share similar morphologic, physiologic and
genetic traits into specific groups.
- Arrangement of organisms into groups
preferably in a format that shows
evolutionary relationships

40. THE CLASSIFICATION SYSTEM IS
HIERARCHIC AND CONSISTS OF THE
FOLLOWING:
1.) DOMAIN – Bacteria and Archaea (unicellular prokaryotic
org)2.) KINGDOM – composed of similar divisions; similarities
of DNA and RNA
3.) DIVISION- composed of similar classes
4.) CLASS- composed of similar orders
5.) ORDER- similar families
6.) FAMILY- composed of similar genera
7.) GENUS- composed of similar species
8.) SPECIES- basic group; collection of bacterial stains with
common physiologic and genetic features
9.) SUBSPECIES- species are subdivided based on
phenotypic differences; SEROTYPE or BIOTYPE

41. 1.) DOMAIN – Bacteria
2.) KINGDOM – Prokaryote
3.) DIVISION- Gracilicutes
4.) CLASS- Scotobacteria
5.) ORDER- Eubacteriales
6.) FAMILY- Enterobacteriaceae
7.) GENUS- Escherichia
8.) SPECIES- Coli
9.) SUBSPECIES- Escherichia coli O157:H7

42. NOMENCLATURE
• It is the naming of microorganisms
according to established rules and
guidelines
• It provides acceptable labels by which
organisms are universally recognized
In writing the genus name, it should be
capitalized and followed by the species
epithet which begins with a lowercase letter
(Both of the genus and species should be
italicized in print and underlined when written
in script)
Example: Staphylococcus aureus or
Staphylococcus aureus

43. ** when bacteria are referred to as
a group, their names are neither
capitalized nor underlined.
Example: staphylococci

44. IDENTIFICATION
• It is the process by which a
microorganism’s key features are
delineated.
• It is the process of discovering and
recording the traits of organisms so
that they may be placed in an overall
taxonomic scheme.
It is the practical use of a
classification scheme to:
a.) isolate and distinguish specific
organisms
b.) verify the authenticity or special
properties of a culture
c.) isolate the causative agent of a
disease which will lead to the
selection of specific pharmacologic

45. GENOTYPIC CHARACTERISTICS
Relates to the organism’s genetic make
up
Involves detection of a gene or a part
thereof, or an rna product of a specific
organism
Serves as confirmatory method for the
presence of organisms

46. PHENOTYPIC
CHARACTERISTICS
It is based on features beyond the
genetic level
It includes readily available
characteristics and those characteristics
that may require extensive analytic
procedures to be detected.

47. MAJOR CHARACTERISTICS
USED IN TAXONOMY
Classical characteristics
Useful in routine identification and
phylogenetic information – morphology,
physiology, and metabolism, ecology and
genetic analysis
 phylogenetic/ phyletic classification-
based on evolutionary relationships
instead of general resemblance
Molecular characteristics
 Based on the study of nucleic acid

48. HOW TO STUDY BACTERIA?

49. HOW TO ISOLATE PURE
CULTURE?
Many bacterial pathogens can be isolated
on solid agar-containing media.
Two types of agar or media: solid
and liquid.

50. HOW TO CLASSIFY BACTERIA?
CRITERIA
:1.) Gram Stain Reactions
2.) Shapes/ Morphology
3.) Arrangement
4.) Growth characteristics
5.) Antigen and phage
susceptibility
6.) Biochemical characteristics

51. Bacterial Morphology and
Ultrastructure

53. Introduction
◉ All bacteria are unicellular organisms that
reproduce by binary fission. Most bacteria are
capable of independent metabolic existence and
growth, but species of Chlamydia and Rickettsia are
obligately intracellular organisms.
◉ Bacterial cells are extremely small and are most
conveniently measured in microns (10-6 m). They are
usually between 0.4 and 1.5 μm in short diameter.

54. Introduction
◉ It is this nucleus that gives
the eukaryote its
name. Eukaryote means true
nucleus.
◉ A prokaryote is a
unicellular organism that lacks
a membrane-bound nucleus
(karyon).

55. Morphology of Bacteria
◉ Bacteria have characteristic shapes. The common
microscopic morphologies are:
spherical or ovoid (cocci)
rod-shaped (bacilli)
comma-shaped (vibrio)
spiral (spirillum and spirochete)

56. Streptococcus pneumoniae
meningococcus

57. Streptococcus,×1500

58. Streptococcus,×12000

59. Staphylococcus

60. tetrad， ×1500

61. BACILLI
bacillus
large medium
E.coli
small
Brucella
Different size

62. Coryneform bacteria
bacilli
Different shape
bifidobacterium

63. vibrio cholerae

64. spirillum
spirochete

65. Structure of Bacteria2

66. Structure of Bacteria
◉ The protoplast is
bounded peripherally by a
very thin, elastic and
semipermeable cytoplasmic
membrane. Outside, and
closely covering this, lies
the rigid, supporting cell
wall, which is porous and
relatively permeable.

67. Essential
structures
Cell wall
Capsules
Plasma membrane
Cytoplasm
Nucleoid (nuclear material)
Flagella
Endospore
Pili (Fimbriae)
Other
structures

68. Nucleoid (nuclear material)
Electron micrograph of a thin section of Neisseria gonorrhoeae showing the
organizational features of prokaryotic cells.

69. Nucleoid (nuclear material)
◉ The bacterial nucleoid contains a single double-stranded
deoxyribonucleic acid (DNA), RNA, RNA polymerase, proteins.
◉ It is a closed circular thread about 1 mm long, being condensed
and looped into a supercoiled state.
◉ Only containing a single chromosome.
◉ Having no nuclear membrane.
◉ No nucleolus.
◉ Replicating by growth and simple fission,
and not by mitosis.

70. Cytoplasm
◉ Matrix where nucleoid and ribosomes are embedded
◉ Inclusion granules are observed in the cytoplasm in many
species of bacteria.
◉ Contains plasmids in some species of bacteria.
◉ No endoplasmic reticulum.
◉ No membrane-bearing microsomes.
◉ No mitochondria.

71. Stained Corynebacterium cells. The "barred"
appearance is due to the presence of
polyphosphate inclusions called metachromatic
granules.

72. Cytoplasm
◉ Contains inclusion bodies or vesicles
- Membrane bound structures
-Used for storage (e.g., carbon compounds, inorganic substances,
and energy),
- Gas vacuoles (N2), carboxysomes (CO2),
magnetosomes (allow bacteria to
orient with earth’s gravity)

73. Plasma membrane
◉ Has a selective permeability and transport of solutes
◉ Electron transport and oxidative phosphorylation in aerobic
species.
◉ Excretion of hydrolytic exoenzymes.
◉ Bearing the enzymes and carrier molecules that function in the
biosynthesis of DNA, cell wall polymers,
and membrane lipids.

74. The cell membrane. Fragments of the cell
membrane (CM) are seen attached to the cell wall
(CW) in preparations made from Escherichia coli.
A model of membrane structure. Folded
polypeptide molecules are visualized as
embedded in a phospholipid bilayer, with
their hydrophilic regions protruding into the
intracellular space, extracellular space, or
both.
The membranes of prokaryotes are
distinguished from those of eukaryotic
cells by the absence of sterols, the
only exception being mycoplasmas.

75. Plasma membrane
◉ Mesosomes
- are convoluted or multilaminated membranous bodies visible in
the electron microscope. They develop by complex invagination of
the cytoplasmic membrane into the cytoplasm.
- functions in the compartment of DNA at cell division and at
sporulation.
- functions analogous to the mitochondria of the eukaryotic cell----
providing a membranous support for respiratory enzymes.

76. A diagram of the attachment of bacterial
chromosomes, indicating the possible role of
the mesosome in ensuring the distribution of
the "chromosomes" in a dividing cell.

77. Cell wall
◉ The cell wall is 10~25nm thick, usually fairly rigid, and lies just
outside the plasma membrane.
◉ Gives bacteria shape and protects it from osmotic lysis;
◉ The cell walls of many pathogens have components that
contribute to their pathogenicity.
◉ Can protect a cell from toxic substances and is the site of action of
several antibiotics.
◉ Peptidoglycan – the most important molecule in the cell walls of
bacteria

78. Cell wall
(A) Electron micrograph of a thin section of the Gram-positive
bacteria
(B) Freeze-fractured Bacteriodes cell

79. Cell wall
◉ Bacteria are classified as gram-positive or gram-negative
according to their response to the Gram staining procedure.

80. Cell wall
Gram-positive bacteria
◉ Peptidoglycan
◉ Teichoic acid
Gram-negative bacteria
◉ Peptidoglycan
◉ Outer membrane

81. Cell wall
◉ Peptidoglycan is a complex polymer consisting of three parts:
- a backbone, composed of alternating N-acetylglucosamine and
N-acetylmuramic acid;
- and a set of identical tetrapeptide side chains attached to N-
acetylmuramic acid;
- and a set of identical peptide cross bridges.

82. Peptidoglycan layer

83. Gram-positive
bacteria

84. Gram-negative
bacteria
Diaminopimelic acid
Unique element of the prokaryotic cell wall
Immediate precursor of lysine in the bacterial
biosynthesis of amino acids
Building block for bacterial proteins

85. Peptidoglycan layer
◉ The fact that all peptidoglycan chains are cross-linked means that
each peptidoglycan layer is a single giant molecule.
◉ In gram-positive bacteria, there are as many as 40 sheets of
peptidoglycan, comprising up to 50% of the cell wall material; in
gram-negative bacteria, there appears to be only one or two sheets,
comprising 5~10% of the wall material.
Whose walls are thicker and stronger?

86. Special components of Gram-Positive Cell Walls:
Teichoic Acids
◉ Teichoic acids are water soluble
polymers, containing ribitols or glycerol
residues joined through phosphodiester
linkages and carrying one or more
amino acid or sugar substituents.
◉There are two types of teichoic acids:
wall teichoic acid (WTA), covalently
linked to peptidoglycan, and membrane
teichoic acid, covalently linked to
membrane glycolipid. Because the latter
are intimately associated with lipids,
they have been called lipoteichoic
acids (LTA).

87. Special components of Gram-Positive Cell Walls:
Teichoic Acids
◉ Function of teichoic acid
(1) Constituting major surface
antigens of those gram-positive
species that possess them.
(2) In Streptococcus pyogenes , LTA is
associated with the M protein that
protrudes from the cell membrane
through the peptidoglycan layer. The
long M protein molecules together with
the LTA form microfibrils that facilitate
the attachment of S. pyogenes to
animal cells.

88. Special components of Gram-Negative Cell Walls:
Lipoprotein Layer
◉ Gram-negative cell walls contain
three components that lie outside of
the peptidoglycan layer:
- lipoprotein
- phospholipid bilayer
- and lipopolysaccharide
◉ Function of Lipoprotein layer
- Stabilize the outer membrane and
anchor it to the peptidoglycan layer

89. Special components of Gram-Negative Cell Walls:
Phospholipid bilayer
◉ made up of plasma-membrane-like
material in the inner portion and the
lipopolysaccharide layer in the outer
portion
◉ Porins
◉ Functions of Lipoprotein layer
- Excluding hydrophobic molecules and
protecting the cell
- Because of its lipid nature, the outer
membrane would be expected to
exclude hydrophilic molecules as well
- Accounts for the relatively high
antibiotic resistance.

90. Special components of Gram-Negative Cell Walls:
Lipopolysaccharide
◉ Extremely toxic to animals
(including humans)
◉ Aka “Endotoxin” (for gram
negative ONLY)
◉ Made up of:
- a. Lipid A - responsible for toxic
effects of lipopolysaccharide layer
- b. Polysaccharide layer- major
surface antigen (O antigen)

91. Periplasmic space
◉ The periplasmic space is
the space between the inner and
outer membrane in Gram-
negative bacteria. In Gram-positive
bacteria a smaller periplasmic
space is found between the inner
membrane and the peptidoglycan
layer.
◉Membrane derived oligosaccharides
- provide metabolic needs of bacteria

92. Capsule and Glycocalyx
◉The glycocalyx exists in bacteria as either
a capsule or a slime layer. The difference between
a capsule and a slime layer is that in
a capsule polysaccharides are firmly attached to
the cell wall, while in a slime layer the glycoproteins
are loosely attached to the cell wall.

93. Capsule and Glycocalyx
◉ Capsule (not all bacteria are encapsulated)
◉Extracellular polymer which forms a condensed, well defined layer around the cell
◉Detected in Neufeld-Quellung reaction
◉Purpose:
- contributes to the invasiveness of the pathogenic bacteria
- Encapsulated cells are more invasive and are protected from phagocytosis, unless
they are coated with an anticapsular antibody (opsonization)
◉Glycocalyx
◉Polymer which forms a loose meshwork of fibrils extending outward from the cell
◉Adherence of bacteria to surface in their environment
◉Ex: Staphylococcus mutans or Streptococcus mitis - found in teeth particularly in
the plaques

94. Capsule and Glycocalyx

95. Flagella
◉ Threadlike appendages that is composed
entirely of proteins
◉ Organ of locomotion (they are capable of
more movement)
◉ 4 types of arrangement:
- 1. Monotrichous - single polar flagellum
- 2. Lophotrichous - multiple polar flagella
- 3. Peritrichous - around the bacteria
- 4. Amphitrichous – both polar flagella

96. Flagella
◉ Composition: Flagellin (H antigen) – important in doing diagnostic test (E. coli
O157:H7)
◉ Aids in:
- Sensory Transduction (to detect areas which can provide their needs)
- Chemotaxis – chemicals
- Aerotaxis - air (where oxygen concentration is high)
- Phototaxis – light
- Electron Acceptor traits
Demonstration -
occurrence of spreading
growth in semi-solid
agar medium

97. Pili /pahy-lahy/, /pahy-lI/; plural of pilus
◉ Rigid surface appendages
◉ Proteins: Pilins
◉ 2 classes:
a) Ordinary pili
- For adhesion or attachment and colonization
- Function: Virulence of pathogenic bacteria
- More virulent due to toxin production (Endotoxin
(G-) and Exotoxin (G+/-)
- colonization antigens make sure bacteria stays
in place
b) Sex pili
- for attachment of two bacteria during the
conjugation process

98. Endospore
◉Endospore
- Resting state of the cell highly resistant to
desiccation
◉ Examples of Spore-forming organisms
- Bacillus (B.anthracis)
- Clostridium (C.tetani)
- Coxiella burnetti

99. Endospore
Parts of Spore:
1. Core
◉ Spore protoplast
◉ Chromosomes
◉ CHON synthesizing apparatus
◉ Energy generating-based on glycolysis
*Resistance due to: Ca dipicolinate
2. Spore Wall
◉ Innermost layer surrounding the inner spore
membrane
◉ Contains peptidoglycan
◉ Becomes the cell wall of the germinating
vegetative cell
3. Cortex
◉ Thickest layer of the spore envelope
◉ Contains unusual peptidoglycans
◉ Extremely sensitive to lysozyme
4. Coat
◉ Keratin-like CHONS containing many disulfide
bonds
◉ Impermeable confers on spores relative
resistance to antibacterial drugs.
5. Exosporium
◉ A lipoprotein membrane containing some
carbohydrate.

100. Variations in endospore morphology:
(1, 4) central endospore; (2, 3, 5) terminal
endospore; (6) lateral endospore
Endospore
◉ The appearance of the mature spores varies
according to the species, being spherical, ovoid
or elongated, occupying a terminal, subterminal
or central position, and being narrower than the
cell, or broader and bulging it.

101. Endospore
Sporulation
◉ Happens in unfavourable nutritional
conditions
◉ Production of many new enzymes,
structures and metabolites
◉ Disappearance of many cell
components
◉ For conservation
◉ Forms a more rigid wall making it more
resistant
***Autoclave is working if it is able to kill
spores
Germination
◉ Opposite of sporulation
◉ Happens if the supply is back to normal
then spore goes back to its original form
◉ Not destroyed by boiling or the use of
alcohol
◉ Spore formation and germination are
reversible processes
◉ 3 Stages:
- 1. Activation
- 2. Initiation
- 3. Outgrowth

102. Thanks!