The count of bacteria should be expressed in colony forming units (CFU), not individual bacteria. Each CFU has approx. 1,000,000 bacteria in that colony (this is when there is enough bacteria to be visible as a colony which can then be counted). For example, a batch test result showing > 10,000 live CFU’s per gram, equates to a minimum of 10,000,000,000 (10 billion) bacteria per gram. Note this is a minimum as the live bacteria are multiplying all the time.
In terms of serving sizes, a child serving of approximately 1.5 grams would give them a MINIMUM of 15 billion bacteria, and an adult serving of 3 grams (one teaspoon) would provide 30 billion bacteria. Again, the bacteria must be alive, so they are multiplying all the time, and it is important that they are also bred to withstand the harsh environment of the gut so they are not immediately killed off upon arrival.