ISO 6461-2 (1993) medium: Sulfite Iron Tryptose Sulfite (TS)

Media control Water quality 

Microorganisms and performance criteria for testing selective media 'Sulfite Iron Tryptose Sulfite (TS)' for Enumeration of Sulfite-reducing anaerobes (clostridia) used in Water quality  microbiology by comparing with a non-selective reference medium according to ISO 11133.

  • Quantitative control of Productivity

  • Best Practice Sulfite Iron Tryptose Sulfite (TS)

    Quantitative control of Productivity solid medium

    1. Use a quantitative reference material or test suspension with a known number of Clostridium perfringens.
    2. Dilute this material so 50 to 120 cfu is inoculated on the Sulfite Iron Tryptose Sulfite (TS) by membrane filtration method.
    3. Place the membrane on the surface of the agar under test (Sulfite Iron Tryptose Sulfite (TS)).
    4. Do this also for the reference media (A suitable nonselective medium for anaerobes or Media batch Sulfite iron already accepted).
    5. Incubate at (37 ± 1) °C for (20 ± 4) h to (44 ± 4) h.
    6. Count the colonies on the medium under test (Sulfite Iron Tryptose Sulfite (TS)) and the reference media (A suitable nonselective medium for anaerobes or Media batch Sulfite iron already accepted).
    7. Calculate the productivity ratio PR. The criteria is: PR ≥ 0,7.
    8. If the PR exceeds 1,4 identify the reason.
    9. For this the total count of colonies obtained on the culture medium under test (Sulfite Iron Tryptose Sulfite (TS)) is divided by the total count of colonies obtained on the defined reference medium (A suitable nonselective medium for anaerobes or Media batch Sulfite iron already accepted).
    Calculate the productivity ratio PR as follows: PR  NS
    N0
    Ns = total count test medium
    N0 = total count reference medium

    Control strain WDCM number Ref. media Incubation Criteria Characteristic reaction
    Clostridium perfringens A suitable nonselective medium for anaerobes or Media batch Sulfite iron already accepted (37 ± 1) °C for (20 ± 4) h to (44 ± 4) h
    anaerobic atmosphere
    PR ≥ 0,7 Black colonies
    The best practice for Quantitative control of Productivity for media control of 'Sulfite Iron Tryptose Sulfite (TS)' is based on the data displayed in this table according ISO 11133.
  • Qualitative control of Specificity

  • Best Practice Sulfite Iron Tryptose Sulfite (TS)

    Qualitative control of Specificity solid medium

    1. Use a reference material or test suspension with a known number of Escherichia coli.
    2. Streak each test controlstrain (Escherichia coli) on the media under test (Sulfite Iron Tryptose Sulfite (TS)) to obtain discrete colonies.
    3. Use a 1 µl loop in case of a concentration of at least 1000 cfu/mL.
    4. Incubate at (37 ± 1) °C for (20 ± 4) h to (44 ± 4) h.
    5. Asses the presence, absence and/or grade of expression of biochemical responses and colony sizes and morphology.
    6. For this medium (Sulfite Iron Tryptose Sulfite (TS)) and standard (ISO 6461-2) combination the characteristic reaction is: No blackening.

    Control strain WDCM number Ref. media Incubation Criteria Characteristic reaction
    Escherichia coli or (37 ± 1) °C for (20 ± 4) h to (44 ± 4) h
    anaerobic atmosphere
    Growth No blackening
    The best practice for Qualitative control of Specificity for media control of 'Sulfite Iron Tryptose Sulfite (TS)' is based on the data displayed in this table according ISO 11133.