Bifidobacterium animalis ssp. lactis BB-12 enumeration by quantitative PCR assay in microcapsules with full-fat goat milk and inulin-type fructans

The current study was conducted to develop a quantitative polymerase chain reaction (qPCR) assay for Bifidobacterium animalis ssp. lactis BB-12 quantification in microcapsules matrix with full-fat goat milk and inulin-type fructans. DNA was isolated from milk, feed solutions (before spray drying) and microcapsules (after spray drying) using DNAzol. Two primer pairs targeting Bal-23S or Tuf sequences were evaluated by qPCR. The qPCR efficiency was higher (89.5%) using the Tuf primers than Bal-23S primers (84.8%). Tuf primer pair was able to selectively detect B. animalis ssp. lactis BB-12. After, quantification of bifidobacteria in the microcapsules matrix by Tuf qPCR assay was compared to conventional enumeration by plate counting. The analysis of probiotic feed solutions and microcapsules showed higher (P < 0.05) bacterial enumeration determined by Tuf qPCR assay compared to those obtained by plate counting. This qPCR assay was considered a rapid and sensitive alternative for the quantification of B. animalis ssp. lactis BB-12 in probiotic microcapsules compared to plate counting.