Basics

1. MICROBIOLOGY
&
MICROBES

2. MICROBES GENERALLY
INCLUDES
Bacteria
Fungi
Algae
Virus
Protozoa
Actinomycetes

3.  Prokaryotes
 Peptidoglycan cell
walls
 For energy, use
organic chemicals,
inorganic chemicals,
or photosynthesis
BACTERIA

4. FUNGI
 Eukaryotic (have membrane-bound
nucleus)
 Obtain food from other organisms
 Possess cell walls
 Composed of
 Molds – multicellular; have
hyphae; reproduce by sexual and
asexual spores
 Yeasts – unicellular; reproduce
asexually by budding; some
produce sexual spores

5. APPLICATION OF MICROBES
Antibiotic production
Enzyme production
Probiotics
Quorum sensing
Bio degradation

6. MICROBIOLOGY
 The science of microorganisms (very small,
unicellular organisms)
 Has given rise to Molecular Biology and
Biotechnology

7. Early Microbiology
3 Historical discoveries
 Invention of the microscope
 Disproving spontaneous generation
 Demonstrating microorganisms cause disease

8. ANTON VAN LEEUWENHOEK
Inventor of the first microscope (1684)

9. THE GOLDEN AGE OF
MICROBIOLOGY
Pasteur’s Experiments
When the “swan-necked
flasks” remained upright,
no microbial growth
appeared
When the flask was tilted,
dust from the bend in the
neck seeped back into the
flask and made the
infusion cloudy with
microbes within a day
 Spontaneous generation:
Life can arise from non-living
materials.
 Pasteur demonstrated that
microorganisms in the air
were responsible for food
spoilage
Constructed a swan-necked
flask

10. GERM THEORY OF DISEASE
 Proof that microorganisms caused
disease
 Robert Koch demonstrated that
anthrax was caused by Bacillus
anthracis
 Blood from a diseased animal
caused disease in a healthy
animal
 Cultivated the disease causing
agent outside the animal’s body,
then introduced the agent into
a healthy animal which
subsequently developed the
disease

11. METHODS IN MICROBIOLOGY
Three important techniques that allowed the
advanced study of microbiology:
 Microscopy
 Sterilisation
 Pure culture

13. STERILISATION TECHNIQUES
Sterilisation using heat
 Dry heat: 160 ° C for 2 h
 Wet heat: Autoclave, 120 °C
Sterilisation using chemicals
 Disinfectants
Filtration
 Filter membranes (Pore size approx. 0.22 µm)
Radiation
 Ultraviolet radiation

14. MEDIA
The survival and continued growth of microorganisms
requires adequate amount of nutrients.
solution containing these nutrients is called culture medium.
Liquid medium – without agar
Semi solid medium – less than 1% agar
Solid medium – 1.5% to 1.8% agar

15. TYPES OF MEDIA
Basal (simple) medium
Generally used for the routine culture of microorganism.
e.g.: Nutrient agar
Selective medium
used for the selective isolation of desired microbes.
e.g.: Lowenstein Jensen medium for Mycobacterium
tuberculosis
Differential medium
used to distinguish differing properties of bacteria.
e.g.: MacConkey’s agar –lactose fermenters from non
lactose fermenters

16. MICROBIAL LIFE CYCLE