Abstract
PurposeIn this study, a PMA-qPCR assay was developed for the enumeration of Bifidobacterium animalis subsp. lactis BB-12 viable cells in a non-dairy probiotic beverage.MethodsProbiotic viability was monitored in three formulations of probiotic passion fruit juice microencapsulated by spray drying, during 30 days of storage at 4 °C. Viable cells were quantified using qPCR and PMA-qPCR assays targeting tuf gene and by plate counting method.ResultsThe limit of detection for all samples was 103 genome copies, corresponding to 21.3 pg of DNA. Higher CFU values were obtained for B. lactis BB-12 enumeration by qPCR, when compared to those obtained by PMA-qPCR and plate count, for all probiotic juice microcapsules. Similar quantification values were obtained by PMA-qPCR and plate counting for all samples and remained above 8 log CFU/g during the storage period.ConclusionThese results demonstrated that the PMA-qPCR technique is a promising approach for B. lactis BB-12 viable cell enumeration in complex matrices such as passion fruit juice microcapsules. This PMA-qPCR assay allowed the achievement of reliable results faster than with the traditional plate counting method.
Highlights
Probiotics are widely known to provide several benefits to the human health, since their administration in adequate amounts improves the balance and composition of the gut microbiota (Hill et al 2014)
The present study aimed to develop a propidium monoazide (PMA)-qPCR assay for enumeration of Bifidobacterium animalis subsp. lactis BB-12 viable cells in probiotic passion fruit juice microencapsulated by spray drying
Standard curves obtained from 10-fold dilutions of B. animalis subsp. lactis BB-12 DNA isolated from pure culture, and three formulations of microencapsulated probiotic passion fruit juice were used to determine the qPCR parameters
Summary
Probiotics are widely known to provide several benefits to the human health, since their administration in adequate amounts improves the balance and composition of the gut microbiota (Hill et al 2014). The recommendation to achieve beneficial health effects is a minimum concentration of 6 log CFU per gram of probiotic product throughout its shelf life, ensuring adequate amounts of viable cells at the time of product consumption (Tripathi and Giri 2014). This requirement represents one of the main technological challenges related to probiotic incorporation in fruit juices, since these products present some characteristics considered unfavorable to the maintenance of bacterial viability, such as the high concentration of organic acids and low pH (Shori 2016). Different encapsulating agents may result in different levels of probiotic survival (Anekella and Orsat 2013)
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