2. • Microorganisms are very small organisms
which cannot be seen with the unaided eye.
• Bacteria, fungi, protozoa, algae, viruses are
examples.
• Some are pathogenic “germ” ; refers to a
rapidly growing cell.
What are Microorganisms?
3. • Ubiquitous
• Only form of life for over half of earths entire
history so show them some respect!!!!
• Humans have co-evolved with microbes.
• In earth’s early history microbes were
responsible for creating an oxygen based
atmosphere.
Impact of Microbes on Earth
10. • Eukaryotic Species
– A group of closely related organisms that breed among
themselves
• Prokaryotic species
– A population of cells with similar characteristics
– Clone population of cells derived from a single cell
– Strain genetically different cells within a clone
• Viral Species
– Population of viruses with similar characteristics that
occupies a particular ecological niche
Terminology in Micro Bio
11.
12. • Prokaryotic cells
– No nucleus
– No membrane bound organelles
– Cell wall
– Mode of transportation
• Eukaryotic cells
– Nucleus
– Membrane bound organelles
– Usually no cell wall – exception fungi
Prokaryotic vs. Eukaryotic
13. • First contained two kingdoms
– Plants and animals
• Eventually a third kingdom was added
– Protista
• Finally Whittaker proposed the fourth
kingdom for bacteria and a fifth kingdom for
fungi
A History of Phylogenetic Trees
16. Bacterial Taxonomy Based on Bergey’s
Manual
• Bergey’s Manual of Bacteriology – five
volume resource covering all known
procaryotes
– classification based on genetic information –
phylogenetic
– two domains: Archaea and Bacteria
– five major subgroups with 25 different phyla
18. • Bacteriology is the study of bacteria
• Mycology is the study of fungi
• Parasitology is the study of protozoa and
parasitic worms
• Recent advances in genomics, the study of an
organism’s genes, have provided new tools for
classifying microorganisms
Modern Studies
20. 3 common shapes
Some unusual shapes also:
Classification based upon anatomical features
21. Typical bacteria measure 2-8 m in length and 0.2-2 m in width. Form associations
such as chains, clusters, and tetrads.
22. Other unusual bacteria
Spirochetes
Cell wall-less
Stalked
Filamentous
Streptomyces
Myxobacteria fruiting bodies
Classification based upon anatomical features
23. Gram Positive v/s
Gram Negative
Hans Christian Gram -- 1884
-- Crystal violet
Gram positive structure
-- thick layer of peptidoglycan
Gram negative structure
-- inner vs outer membranes
-- lipopolysaccharides and
endotoxins
Classification based upon staining
24. Why study Bacterial Cell Structure?
Mechanisms of virulence
Drug development
Identification
Some cell exterior structures
cell wall
cell membrane (lipid bilayer)
capsule
flagellum
pilli
25. Cell wall
• Made up of peptidoglycan.
•Responsible for the rigidity of bacterial cell.
26. Cell Membrane Structure
Inner to cell wall,
there is a delicate
cytoplasmic membrane
which surrounds the
cytoplasm.
Phospholipid bilayers
Membrane proteins
Membrane fluidity
Membranes of
thermophilic archaebacteria
30. Endospores
Bacillus species can form spores.
It is produced within the cell, one spore is formed within a single bacterial cell.
It is resistant to heat, UV light, most chemicals and desiccation.
When conditions are favorable, the spore germinates and produces a fresh vegetative cell.
34. Nucleoid (Genetic material) Unlike virus, bacteria have both DNA and RNA.
It contains genetic charateristics.
Nucleoid
35. Nutritional Requirements
Microorganisms require about ten elements in large
quantities, because they are used to construct
carbohydrates, lipids, proteins, and nucleic acids. Several
other elements are needed in very small amounts and
are parts of enzymes and cofactors.
37. Microbial Nutrition
1. Macronutrients: required in large amounts, including: carbon,
oxygen, hydrogen, nitrogen, sulfur, phosphorus (Components of
carbonhydrates, lipids, proteins, and mucleic acids ); potassium,
calcium, magnesium and iron (cations and part of enzymes and
cofactors).
2. Micronutrients: Microbes require very small amounts of other
mineral elements, such as iron, copper, molybdenum, and zinc;
these are referred to as trace elements. Most are essential for
activity of certain enzymes, usually as cofactors.
Contaminants in water, glassware, and regular media components often
are adequate for growth.
38. Growth Factors
Amino acids are needed for protein synthesis.
Purines and pyrimidines for nucleic acid synthesis.
Vitamins are small organic molecules that usually make up all or
part enzyme cofactors;
And only very small amounts are required for growth.
(1)amino acids, (2) purines and pyrimidines, (3) vitamins
39. Nutrition Based Classification
of Bacteria
Phototrophs
• The organisms which depend on sunlight as a
major source of energy are called phototrophs
Chemotrophs
• Other organisms which use chemicals as a
source of energy are called chemotrophs.
Heterotrophs
• Hetrotrophs may either use sunlight or chemical
compouds as energy source
40. Nutritional Types of Microorganisms
• Lithotrophs:- Use reduced inorganic
substances as their electron source.
• Organotrophs:- Extract electrons from
organic compounds.
42. Major nutritional
type
Sources of energy,
hydrogen/electrons,
and carbon
Representative
microorganisms
Photoautotroph
(Photolithotroph)
Light energy, inorganic
hydrogen/electron(H/e-)
donor, CO2 carbon source
Algae, Purple and green
bacteria, Cyanobacteria
Photoheterotroph
(Photoorganotroph)
Light energy, inorganic
H/e- donor,
Organic carbon source
Purple nonsulfur bacteria,
Green sulfur bacteria
Chemoautotroph
(Chemolithotroph)
Chemical energy source
(inorganic), Inorganic H/e-
donor, CO2 carbon source
Sulfur-oxdizing bacteria,
Hydrogen bacteria,
Nitrifying bacteria
Chemoheterotroph
(Chenoorganotroph)
Chemical energy source
(organic), Organic H/e-
donor, Organic carbon
source
Most bacteria, fungi,
protozoa
Nutritional types of microorganisms
43. Mixotrophic: many purple nonsulfur bacteria
1. No oxygen: photoorganotrophic heterotrophs
2. Normal oxygen: oxidize organic molecules
and function chemotrophically.
3. Low oxygen: photosynthesis and oxidative
metabolism
44. Temperature Based
Classification of BacteriaPsychrophiles
Love to
grow in the
range of 0
degree
Celsius - 25
degree
Celsius
Mesophiles
Love to
grow
between 25
degree
Celsius - 40
degree
Celsius
Thermophiles
Love to
grow in the
range of 40
degree
Celsius - 85
degree
Celsius
Some species even grow at 98 degree Celsius
as in hot sulfur spring
45. pH Based Classification of
Bacteria
Acidophiles
Neutrophiles
Alkalophiles
• Love to grow in
the range of pH
between 0-6
• Love to grow
between 6-8
pH
• Love to grow at
pH above 8
47. Obligate aerobes
Must grow in the presence of air
They can not carry out fermentation
Microaerophilic bacterium
Grow well in low concentrations of oxygen
Killed by higher concentrations of oxygen
Facultative anaerobe
Perform both fermentation and aerobic respiration
Can survive in the presence of oxygen
Obligate anaerobes
Grow in the absence of molecular oxygen
Some of these are killed by oxygen
Further Classification based on
Environmental conditions
