Tergitol-7 HiVeg™ Agar Base

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SKU:
MV616
For selective enumeration and identification of coliform organisms.


Intended Use

Recommended for selective enumeration and identification of coliform organisms.

Composition

Ingredients g/L
HiVeg® peptone No. 3 5.000
Yeast extract 3.000
Lactose 10.000
Tergitol 7 (Sodium heptadecyl sulphate) 0.100
Bromo thymol blue 0.025
Agar 15.000
Final pH (at 25°C) 6.9±0.2

**Formula adjusted, standardized to suit performance parameters

Directions

Suspend 33.13 grams in 1000 ml purified/distilled water. Heat to boiling to dissolve the medium completely. Sterilize by autoclaving at 15 lbs pressure (121°C) for 15 minutes. Cool to 45-50°C. Aseptically add 3 ml of TTC Solution 1% (FD057), if desired. Mix well and pour into sterile Petri plates.

Principle And Interpretation

Tergitol-7 Agar was originally designed by Chapman (1) and later on modified by incorporating 2,3,5-Triphenyl Tetrazolium Chloride (TTC) into the medium. This medium is selective and differential used for the detection and enumeration of coliform organisms. Pollard (2) has reported the selective bactericidal property of sodium heptadecyl sulphate (Tergitol-7). Kulp et al (3) corroborated the use of Tergitol-7 Agar with TTC in routine analysis of water and Mossel (4) used this medium for the examination of food materials.

Tergitol-7 HiVeg® Agar Base is prepared by completely replacing animal based peptone with vegetable peptones to avoid BSE/TSE risks associate with animal peptones. HiVeg® peptone No. 3 and yeast extract serve as sources of carbon, nitrogen and other essential nutrients including vitamin B complex.

Sodium heptadecyl sulphate (Tergitol-7) inhibits gram-positive bacteria and Proteus swarming and yields better recovery of coliforms. Bromo thymol blue is the pH indicator. Lactose fermenting organisms form yellow colonies with yellow zones while Klebsiella and Enterobacter form greenish yellow colonies. Lactose non-fermenters produce blue colonies. TTC is reduced by the bacterial cell except Escherichia coli and Klebsiella aerogenes to form formazan, a red coloured insoluble complex, thereby producing red coloured colonies.

Filter the specimen to be analyzed through two membranes. Place the membrane upon two TTC Tergitol Agar plates. Incubate one plate at 37°C for 24 hours (total coliforms) and the other at 44°C for 18-24 hours (faecal coliforms). The yellow colonies with deep yellow halo after incubation at 44°C should be identified as faecal coliform bacteria.

Type of specimen

Water samples

Specimen Collection and Handling

Filter the specimen to be analyzed through two membranes. Place the membrane upon two TTC Tergitol Agar plates. Incubate one plate at 37°C for 24 hours (total coliforms) and the other at 44°C for 18-24 hours (faecal coliforms). The yellow colonies with deep yellow halo after incubation at 44°C should be identified as faecal coliform bacteria.

Warning and Precautions

Read the label before opening the container. Wear protective gloves/protective clothing/eye protection/face protection. Follow good microbiological lab practices while handling specimens and culture. Standard precautions as per established guidelines should be followed while handling specimens. Safety guidelines may be referred in individual safety data sheets.

Limitations

  1. Further biochemical and serological tests must be carried out for complete identification.

Performance and Evaluation

Performance of the medium is expected when used as per the direction on the label within the expiry period when stored at recommended temperature.

Quality Control

Appearance
Cream to light green homogeneous free flowing powder

Gelling
Firm, comparable with 1.5% Agar gel

Colour and Clarity of prepared medium
Green coloured clear to slightly opalescent gel forms in Petri plates

Reaction
Reaction of 3.31% w/v aqueous solution at 25°C. pH: 6.9±0.2

pH
6.70-7.10

Cultural Response
Cultural characteristics observed after an incubation at 35-37°C for 18-48 hours with added TTC Solution 1% (FD057).

Organism Inoculum (CFU) Growth Recovery Colour of colony/
medium
# Klebsiella aerogenes ATCC 13048 (00175*) 50-100 luxuriant >=50% Reddish brown
Escherichia coli ATCC 25922 (00013*) 50-100 good-luxuriant >=50% yellow with red centre
Proteus mirabilis ATCC 25933 50-100 good 40-50% red with bluish zone
Pseudomonas aeruginosa ATCC 27853 (00025*) 50-100 good 40-50% red with bluish zone
Salmonella Typhimurium ATCC 14028 (00031*) 50-100 luxuriant >=50% red with bluish zone
Staphylococcus aureus subsp. aureus ATCC 25923 (00034*) >=104 inhibited 0%
Shigella flexneri ATCC 12022 (00126*) 50-100 good-luxuriant >=50% red with bluish zone

Key: (*) Corresponding WDCM numbers. (#) Formerly known as Enterobacter aerogenes

Storage and Shelf Life

Store between 10-30°C in a tightly closed container and the prepared medium at 2-8°C. Use before expiry date on the label. On opening, product should be properly stored dry, after tightly capping the bottle in order to prevent lump formation due to the hygroscopic nature of the product. Improper storage of the product may lead to lump formation. Store in dry ventilated area protected from extremes of temperature and sources of ignition. Seal the container tightly after use. Product performance is best if used within stated expiry period.

Disposal

User must ensure safe disposal by autoclaving and/or incineration of used or unusable preparations of this product. Follow established laboratory procedures in disposing of infectious materials and material that comes into contact with sample must be decontaminated and disposed of in accordance with current laboratory techniques (5,6).

More Information
Product Name Tergitol-7 HiVeg™ Agar Base
SKU MV616
Product Type HiVeg™
Physical Form Powder
Origin Animal Free (Veg)
Packaging type HDPE
References 1.Chapman G.H., 1947, J. Bact., 53:504.
2.Pollard A.L., 1946, Science, 103:758.
3.Kulp W., Mascoli C. and Tavshanjian O., 1953, Am. J. Public Health, 43:1111.
4.Mossel D.A.A., 1962, J. Appl. Bact., 25:20.
Customized Product Available No
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