This document provides an overview of microbiology and microbes. It defines microbes as including bacteria, fungi, algae, viruses, protozoa, and actinomycetes. It describes key early discoveries in microbiology including the invention of the microscope, disproving spontaneous generation, and demonstrating that microorganisms cause disease. It also summarizes techniques that advanced the study of microbiology such as microscopy, sterilization, and using pure cultures.

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