This document discusses various microbiological techniques used to isolate and identify pathogenic microorganisms, including bacterial culture media and biochemical tests. It provides details on nutrient agar, blood agar, MacConkey agar, catalase, oxidase, coagulase, indole, methyl red, Voges-Proskauer, citrate, urease, motility, nitrate reduction, carbohydrate fermentation, agglutination, polymerase chain reaction (PCR) tests. The document emphasizes that biochemical tests are commonly used in laboratories to identify microorganisms based on their biochemical reactions. Advanced methods like PCR can also be used depending on genetic material.

1. NEEHARA.K
16-MSVM -016
Msc Quality control in dairy
industry

2.  Done for isolation and identification of
pathogenic microorganisms and their
control
 Several methods are available
 Isolated from food particles, Medical
sample

5.  NUTRIENT AGAR:
 General purpose medium
 Supporting growth of non-fastidious organisms.
 Streak on nutrient agar
 Identify pigment producing organism

7.  Contains general nutrients and 5% sheep blood.
 Useful for cultivating fastidious organisms
 For determining the hemolytic capabilities of an
organism.

9.  Selective,differential culture medium
 Selectively isolate Gram-negative organism
 Differentiate them based on lactose fermentation
 The crystal violet and bile salts inhibit the growth
of gram-positive organisms.

12. Used to differentiate those bacteria that produce
the enzyme catalase
PRINCIPLE
Catalase act as a catalyst in the break down of
H2O2 into H2O and O2
Catalase positive: Staphylococcus aureus
 Catalase negative: Streptococcus sps

13. 

15. Identify bacteria that produce cytochrome c oxidase

16.  Oxidase positive : Pseudomonas aeruginosa
 Oxidase negative: Escherichia coli

17.  PRINCIPLE
Identifies the organism produces the enzyme
coagulase, which causes the fibrin of blood plasma to
clot.
 To differentiate Coagulase positive staphylococcus
sps from CONS
 Coagulase positive: Staphylococcus aureous
 Coagulase negative: Staphylococcus epidermidis

18. PROCEDURE

22.  Indole positive: Escherichia coli
 Indole negative: Klebsiella sps

23.  PRINCIPLE
 Are used to differentiate species of the family
Enterobacteriaceae.
 MR—tests for acid end products from glucose
fermentation.
 VP—tests for acetoin production from glucose
fermentation.
 Media and Reagents Used:
 Glucose Broth
 Methyl Red indicator
 Voges Proskauer reagents—A: 5% Alpha-Naphthol, &
ethanol, B: Potassium Hydroxide, & Deionized Water.

25. +

26.  PRINCIPLE
Used to differentiate species of the family
Enterobacteriaceae.
Ability of bacteria to consume citrate as its sole source
of carbon and ammonium as sole nitrogen source.
 MEDIA
Simmon’s Citrate Agar Sodium citrate
Ammonium ion
pH indicator

27.  PROCEDURE
Inoculate slant with inoculating loop.
 RESULTS:
Citrate positive: :Klebsiella
 Citrate negative: E.coli

28. PRINCIPLE:
MEDIA
Urea Ammonia

29.  RESULT
 Positive: Helicobacter pylori
 Negative: Salmonella

30.  PRINCIPLE
Differentiate motile or non motile organisms
 Media :Tryptose, NaCl, agar & color indicator.
 PROCEDURE
Stab motility media with inoculating needle.

31.  RESULT.

32.  To detect ability of a bacteria to reduce nitrate
to nitrate
 PRINCIPLE
Nitrate
reductase

34.  It is to study oxidative and fermentative
breakdown of carbohydrate
 PRINCIPLE

35. PRINCIPLE
Differentiate species of the family Enterobacteriaceae.
Sugar Acid &/ Gas
MEDIA:
Sugar broth (beef extract, peptone, & sugar)
 A phenol red indicate an acid end product.
A durhams tube is added to indicate gas production.
PROCEDURE
Inoculate broth with inoculating loop.
Ferment

37. PRINCIPLE
Glucose/Lactose/Sucrose Acid/gas/H2S
MEDIA : Glucose, Sucrose, Lactose, Ferrous sulphate,
pH indicator phenol red
PROCEDURE
Stab the media with inoculum
Ferment

39.  Involves the interaction of a microbial antigen with
an antibody(produced by the host immune system)
 Testing for microbial antigen or the production of
antibody is often easier than for the microbe itself
 Lab kits based on this technique is available for
the identification of many microorganism.

40.  Most advanced and sensitive method used to identify
microorganism
 Microorganism can be identified depending upon their
genetic materials
 Example : Polymerase Chain Reaction(PCR)

41. o Microorganism can be isolated and identified by using
different methods
o Most commonly used method is depending upon their
biochemical reactions
o Wide variety of biochemical test are available for the
detection of microorganisms
o These test are mainly used in laboratories to identify
microorganism

42. REFERENCE
 Anandanarayanan and Paniker’s Text book
of microbiology edition 7th
Edition page no
62,353
 Tille P. Bailey & Scott's Diagnostic
Microbiology-E-Book. Elsevier Health Sciences;
2013 Aug 13. 13th
edition
 Collee, J. E. "Mackie and McCartney practical
medical microbiology." (1989).
 Biochemical Methods for Bacteriology BY
PATRICIA H. CLARKE AND S. T. COWAN