Thursday 6 August 2015

What are selective, differential, enriched, nutrient and minimal media?

In microbiology, we use different type of media on routine basis. Different media have different properties and used for different type of microorganisms. Different types of media are mentioned below.

Selective Media:
Selective media are those media which are used to support growth of one group of microorganisms but inhibit the growth of other group of microorganisms. For example in case of Mannitol salt agar media. It contains very high amount of salt (7.5%) which inhibit the growth of gram negative bacteria and it is selective for gram positive bacteria like staphylococcus. MacConkey agar media is also selective for gram negative bacteria and other bacteria which found in the intestinal track. MacConkey agar contains bile salts and crystal violet which inhibit the growth of gram positive bacteria.

Differential Media:
Differential media are those media which are used to distinguish closely related microorganisms based on their morphology on different agar media. For example in case of Mannitol salt agar, it contains mannitol and phenol red as pH indicator which support the growth of mannitol fermenting staphylococcus. Acid produced due to mannitol fermentation is detected and due to presence of phenol red indicator dye staphylococcus shows yellow coloured colonies on mannitol salt agar media. MacConkey agar is also differential media which contains lactose and it support the growth of lactose fermenting bacteria like E.coli.

MacConkey Agar Media 
Mannitol Salt Agar Media
So, media could be both selective as well as differential.

Enriched media:
These media support the growth of wide variety of microorganisms and doesn't inhibit the growth of microorganisms. These media contains high amount of nutrients and mainly used to harvest the all types of microorganism which are present in the sample. For example Soyabean casein digest medium is used for enrichment of samples.

Nutrient media:
These media are also called general purpose media. These media are non selective and they contain general nutrients which required for the growth of wide range of microorganisms. Soyabean casein digest agar and Nutrient agar are the example of this type of media.

Minimal media:
Minimal media are those media which contains minimal nutrients for the growth of microorganisms. These media are mainly used for fastidious microorganisms. R2A media is an example of minimal media in which nutrients are present in very small amount.

List of media with Quantity, pH requirement and other Characteristics.

Media Details
S.No.
Name of Media
Quantity Required
pH
Remark
1
RVSEM
27.11g/1000 ml
5.2±0.2
115°C for 15 Minutes,10 lbs pressure
2
SDA
65.0g/1000 ml
5.6±0.2
121°C for 15 Minutes,15 lbs pressure
3
RCM
37.54g/1000 ml
6.8±0.2
121°C for 15 Minutes,15 lbs pressure
4
RCA
51.0g/1000 ml
6.8±0.2
121°C for 15 Minutes,15 lbs pressure
5
PCA
23.50g/1000 ml
7.0±0.2
121°C for 15 Minutes,15 lbs pressure
6
PAF
38.0g/1000 ml
7.0±0.2
121°C for 15 Minutes,15 lbs pressure
7
PAP
46.40g/1000 ml
7.0±0.2
121°C for 15 Minutes,15 lbs pressure
8
GN Broth
39.0g/1000 ml
7.0±0.2
115°C for 15 Minutes,10 lbs pressure
9
MA
49.53g/1000 ml
7.1±0.2
121°C for 15 Minutes,15 lbs pressure
10
EMB Agar
37.46g/1000 ml
7.1±0.2
121°C for 15 Minutes,15 lbs pressure
11
FTGM
29.75g/1000 ml
7.1±0.2
Contains 0.75g/L Agar 
121°C for 15 Minutes,15 lbs pressure
12
Peptone Water
15.0g/1000 ml
7.2±0.2
121°C for 15 Minutes,15 lbs pressure
13
Bacteriological Peptone
0.1%
NA
For Sterility testing
121°C for 15 Minutes,15 lbs pressure
14
R2A
18.12g/1000 ml
7.2±0.2
121°C for 15 Minutes,15 lbs pressure
15
CA
45.30g/1000 ml
7.2±0.2
1.0% Glycerol (10 ml)
121°C for 15 Minutes,15 lbs pressure
16
EEBM
42.93g/1000 ml
7.2±0.2
Do not Autoclave
17
SCDA
40.0g/1000 ml
7.3±0.2
121°C for 15 Minutes,15 lbs pressure
18
SCDM
29.77g/1000 ml
7.3±0.2
121°C for 15 Minutes,15 lbs pressure
19
MB
34.51g/1000 ml
7.3±0.2
121°C for 15 Minutes,15 lbs pressure
20
XLDA
54.80g/1000 ml
7.4±0.2
Do not Autoclave
21
TSIA
64.52g/1000 ml
7.4±0.2
121°C for 15 Minutes,15 lbs pressure
22
MSA
111.02g/1000 ml
7.4±0.2
121°C for 15 Minutes,15 lbs pressure
23
VRBGA
40.62g/1000 ml
7.4±0.2
Do not Autoclave



Thanks and have a nice day!








2 comments:

  1. Why pseudomonas aeruginosa used for TSIT or microbial challenged test

    ReplyDelete
  2. Why pseudomonas aeruginosa used for TSIT or microbial challenged test

    ReplyDelete