Billion live bacteria vs colony forming units | Activated Probiotics


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Billion live bacteria vs colony forming units


Have you ever wondered why the number of bacteria in many probiotic supplements is measured as ‘colony forming units’ (CFUs), and what it actually means?

And why do our products use ‘billion live bacteria’ (BLB), instead?

Let’s take a look at the differences between the two, and what they mean.

What is a colony forming unit?

In any given dose of probiotic bacteria, you will often be ingesting billions of ‘colony forming units’ which roughly corresponds to how many individual bacteria you are consuming.

Viable bacteria can be grown on agar plates which provide them with the nutrients they need to replicate and form colonies.

Once an individual bacteria has replicated enough times to form a colony, it is now large enough to see on an agar plate and can be counted by eye. The number of colonies produced by a sample of probiotic bacteria is used to calculate how many ‘colony forming units’ or individual viable bacteria are present. This is known as a plate count.

The limitations of plate counts

However, this methodology has its limitations and is an imprecise and unreliable method of counting.

Standardised methodologies are not used, and the processes used between different manufacturers vary widely.

One of the reasons why methods vary so widely is that different agar plates and growing environments need to be used to count different species of probiotic bacteria. Using plate counts for multi-species probiotic products (most probiotics available on the market) can be especially difficult because of their different requirements.

There will be discrepancies between the number of CFUs counted from the same sample by two different labs, and this makes it difficult to ascertain how many live bacteria are actually present.

Flow cytometry technology

That’s why at Activated Probiotics we measure the number of viable bacteria using flow cytometry technology.

Flow cytometry technology is able to measure the number of viable bacteria more accurately, analysing bacteria one-by-one using fluorescent staining techniques and lasers which create a measurement known as ‘active fluorescent units’ or ‘billion live bacteria’.

Specific fluorescent dyes will stain damaged and dead bacteria a certain colour, making them distinguishable from viable bacteria. The number of damaged or dead cells can then be detected by the lasers as they pass through a nozzle and subtracted from the total number of bacteria. This achieves a count that more accurately reflects the number of viable living bacteria compared to those achieved by plate count methods.

Live Probiotic Promise

Measuring probiotic bacteria using flow cytometry technology gives us greater confidence in the quality of our products because we know exactly how many living and viable bacteria are in each dose.

With the use of our accurate counting technology, our Live Probiotic Promise guarantees that our products will contain the number of viable probiotic bacteria stated on the label, as a minimum, right up until the end of their shelf life (24 months from their date of manufacture).


Pane M, Allesina S, Amoruso A, Nicola S, Deidda F, Mogna L. (2018) ‘Flow Cytometry: Evolution of Microbiological Methods for Probiotics Enumeration’, Journal Clinical Gastroenterology 2018, May 14




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