The effect and the efficacy of probiotics are typically strain-dependent characteristics. As a consequence of this, current regulations on the labelling of probiotics in food products and the use of health claims requires that each product must be associated with a clear identification of the strain used in the formulation and with a quantitative declaration of the amount of the probiotic contained in the product at the end of its shelf life.
ProDigest developed a pipeline for probiotic strain characterization based on the following steps:
- Number of viable bacteria in the product. This information is typically coupled with live/dead analysis using flow cytometry in order to evaluate the integrity the bacterial cell wall.
- Number of different species in the product: the use of Denaturing Gradient Gel Electrophoresis (DGGE) allows to create a barcode of the different microbial species in the product.
- Number of different strains in the product: colony picking in combination with BOX-PCR provides a barcode typical for each probiotic strain.
- Final confirmation of the identity of probiotic strains: sequencing of the 16S rDNA gene of the probiotic strain allows to confirm its genetic identity. Finally, AFLP is regarded as THE technique to get final confirmation of the strain’s identity by comparison of the genetic profile with a reference database.