Identification and characterisation of bifidobacteria in infant formula milk powder obtained from the Chinese market

Strains of Bifidobacterium animalis subsp. lactis (BAL) are the most commonly added probiotic strains in infant formulas on the Chinese market. In this study, four genotyping methods, 16S rRNA sequencing, multilocus sequence typing, pulsed-field gel electrophoresis and single nucleotide polymorphism-insertion deletion polymorphism were used to determine the 30 isolates from 20 commercial products at the species and strain levels. A combination of the label analysis, quantification and identification results showed that the label claims from the 20 samples had an overall accuracy of 80%. This study was the first to use molecular techniques to identify bifidobacteria strains in probiotic infant formulas on the Chinese market. The results demonstrated that the combination of genotyping methods can effectively identify commonly used commercial BAL strains with similar genetic backgrounds and highlight the importance of accurate strain identification by manufacturers to ensure product legitimacy and to avoid potential health risks.