5. Simple media / basal media:
• Most common in routine diagnostic laboratories
• Eg: nutrient broth, nutrient agar
6. COMPLEX MEDIA
• Media other than basal media.
• Added complex ingredients (Yeast extract) Provide special nutrients
SYNTHETIC OR DEFINED MEDIA
* Prepared from pure chemical substances
* Used for special studies,
Eg. Metabolic requirements
7. SPECIAL MEDIA
• Substances like blood, serum, egg are added to the basal medium.
Eg: Blood agar, Chocolate agar
8. ENRICHMENT MEDIA
• Liquid media used to isolate pathogens from a mixed culture.
• Stimulate growth of desired bacterium inhibit growth of unwanted bacterium
Selenite F Broth – for the isolation of Salmonella, Shigella
Tetrathionate Broth – inhibit coliforms
Alkaline Peptone Water – for Vibrio cholerae
10. SELECTIVE MEDIA
• The inhibitory substance is added to a solid media
• Increase in number of colonies of desired bacterium
EMB – E.coli
11. • DIFFERENTIAL MEDIA
• Substances incorporated in it enabling it to distinguish between bacteria.
• Eg: Mac conkey’s medium
Lactose fermenters – Pink colonies
Non lactose fermenters – colourless colonies
12. SUGAR MEDIA
• Media containing any fermentable substance.
• Eg: Glucose, Arabinose, Lactose, Starch etc.
• Media consists: 1% of the sugar in peptone water + indicator
• Contain a Durham's tube for the detection of gas by the bacteria
14. CULTURE METHODS
• To isolate bacteria in pure cultures.
• To demonstrate their properties.
• To determine sensitivity to antibiotics
• To estimate viable counts.
• Maintain stock cultures.
16. • STREAK CULTURE
• Used for the isolation of bacteria in pure culture from clinical
• Platinum wire or Nichrome wire is used.
17. • LAWN CULTURE
• Provides a uniform surface growth of the bacterium.
• Uses – for bacteriophage typing.
– Antibiotic sensitivity testing.
– In the preparation of bacterial antigens and vaccines.
• Lawn cultures are prepared by flooding the surface of the plate with a
liquid suspension of the bacterium
19. • STAB CULTURE
Prepared by puncturing a suitable medium – gelatin or glucose agar with a
long, straight, charged wire.
– Demonstration of gelatin liquefaction.
– Oxygen requirements of the bacterium under study.
– Maintenance of stock cultures.
20. • STROKE CULTURE
• Made in tubes containing agar slopes (slant).
• Employed for providing a pure growth of the bacterium for slide
agglutination and other diagnostic tests.
21. POUR - PLATE METHOD
• In this, successive dilutions of inoculum
is added to molten agar in respective petriplates.
• Individual colonies are picked for sub culturing.
SPREAD – PLATE METHOD
In this, dilute sample is placed onto solidified agar
and is spread uniformly with sterile ,bent glass rod.
27. • GAS PAK JAR
• Palladium aluminium coated pellets
- Chemically reduces O2
- Reacts with residual O2 in
the presence of H2 to form H2O
29. • SIMPLE STAINING DIFFERENTIAL STAINING
For visualization of
arrangement Identification Visualization of
30. Simple staining
Methylene blue , Carbol fuchsin or Crystal violet
Determination the size ,shape and arrangement
of bacterial cell.
32. GRAM’S STAINING
Gram stain is fundamental to the phenotypic
characterization of bacteria.
1. Primary stain (Crystal violet)
2. Mordant (Gram’s iodine),
3. Decolourisation with ethanol or acetone
4. Counter staining with safranin
35. •SPORE STAINING
Used to visualize bacterial endospores.
Endospores are formed by a few genera of bacteria, such as bacillus
• Primary stain- Malachite green
• Mordant -heating
• Decolorizing agent - H2O
• Counter stain- safranin
36. CAPSULE STAINING
• Detects presence of bacterial capsule
• Place a small drop of a India ink, Congo red, Nigrosin on the
• Drain the dye by the slide.
38. MOTILITY TEST
Bacteria are suspended in a drop
of liquid they can be seen by
Motile bacteria swim in straight line
non motile bacteria vibrate
a bit Brownian motion
39. METHYLENE BLUE DYE REDUCTION TEST
• Quick method
• To assess microbiological quality of raw and pasteurized milk.
• Based on the blue colour of the dye solution added to the milk
get decolourized when the oxygen present in the milk get exhausted due to
• The sooner the decolourization, more inferior is the bacteriological quality
40. 5 hrs and above Very good
3 to 4 hrs Good
1 to 2 hrs Fair
Less than ½ hrs Poor
10 ml milk in a
sterile test tube
1ml MBRT dye
41. RESAZURIN DYE REDUCTION TEST
Also used for testing
microbiological quality of milk
10 milk in a sterile test tube
1ml resazurin dye
Placed in water bath(37±1ºC)
Compare the colour of test tube
with standard disc in comparator
43. • CATALASE TEST
• To differentiate members of the family Microcococcaceae (including
Staphylococcus) and Streptococcus species which are catalase negative
2 H202 -------------- 2 H20 + O2
bubbles or effervescence
A. Positive – Staphylococcus aureus.
B. Negative – Streptococcus pyogenes
44. • COAGULASE
To determine the ability of the organism to produce coagulase
which clots plasma
A. Negative – Staphylococcus epidermidis
B. Positive – Staphylococcus aureus
A. Positive – Staphylococcus aureus
B. Negative – Staphylococcus epidermidis
45. • OXIDASE TEST
Identify bacteria that produce cytochrome c oxidase
diamine hydrochloride Purple colourCytochrome
A. Positive – Staphylococcus aureus
B. Negative – Escherichia coli
46. • UREASE TEST
• To determine the ability of an organism to produce the enzyme, urease,
which hydrolyzes urea.
Positive - Proteus spp.
Negative - Escherichia coli
54. 1. Ananthanarayan and paniker, r. Ananthanarayan, c. K. Jayaram paniker
2005.,ananthanarayan and paniker's textbook of microbiology 9th edition
Pg no 5-9, 10-15, 37-45
1. joanne m. Willey, linda sherwood, christopher j. Woolverton – 2011
Prescott's microbiology pg no 45-50, 49-55, 333-335
1. ‘https://www.ncbi.nlm.nih.gov › NCBI › Literature › PubMed Central (PMC)