CFU Plate Count Procedure

The procedures below demonstrate how we at Master Supplements, Inc. calculate the Colony Forming Units for our products.

Theralac®

  1. Aseptically empty 5 Theralac® capsules into a sterile container, recording the weight from each capsule. Mix.
  2. Weigh out 1.0 gram of the mixed sample into a sterile stomacher bag.
  3. Aseptically add 99.0 mls of sterile, room temperature MRS broth (DIFCO) to the Theralac® powder to make a 1:100 dilution.
  4. Stomach the sample for 5 minutes at high speed.
  5. Hold the sample for 30 minutes.
  6. Stomach the sample for 5 minutes at high speed.
  7. Serial dilutions are made in 0.1% peptone dilution blanks. Add 1.0 ml of the above dilution to 99.0 mls of diluent. Shake the dilution 100 times. This is the 10-4 dilution. Repeat the dilution and mixing step until the desired dilution factors are reached.
  8. For this product, plating the 10-8, 10-9, and 10-10 dilutions should cover the countable range. Pour plates in triplicate for each dilution using DIFCO MRS agar with 1.0 ml of sterile 5% cysteine-HCL solution added to each 100 mls of media.**
  9. Incubate plates at 37° C under anaerobic conditions for 72 hours. **
  10. Count the colonies on each plate. Average the counts within a dilution. This gives the CFU/gram.
  11. Calculate the Colony Forming Units (CFU's) per capsule by multiplying the average count per dilution by the average weight per capsule from step #1.

TruFlora®

Repeat the same steps as for Theralac®, except do NOT add cysteine-HCL to the MRS agar and incubate Aerobically.

Granular Theralac®

  1. Aseptically weigh 1.0 gram of Granular Theralac® into a sterile stomacher bag.
  2. Aseptically add 99.0 mls of sterile, room temperature MRS broth (DIFCO brand) to the powder to make a 1:100 dilution.
  3. Stomach the sample for 5 minutes at high speed.
  4. Hold the sample for 30 minutes.
  5. Stomach the sample for 5 minutes at high speed.
  6. Serial dilutions are made in 0.1% peptone dilution blanks. Add 1.0 ml of the above dilution to 99.0 mls of diluent. Shake the dilution 100 times. This is the 10-4 dilution. Repeat the dilution and mixing step until the desired dilution factors are reached.
  7. For this product, plating the 10-8, 10-9, and 10-10 dilutions should cover the countable range. Pour plates in triplicate for each dilution using DIFCO MRS agar with 1.0 ml of sterile 5% cysteine-HCL solution added to each 100 mls of media.
  8. Incubate plates at 37° C under anaerobic conditions for 72 hours.
  9. Count the colonies on each plate. Average the counts within a dilution. This gives the CFU/gram.
  10. Calculate the Colony Forming Units (CFU's) per serving by multiplying the average count per dilution by 0.75 (the weight of one serving).