Development of a quantitative PCR assay for rapid detection of Lactobacillus plantarum and Lactobacillus fermentum in cocoa bean fermentation
Fieseler, Lars; Gantenbein-Demarchi, Corinne; Miescher Schwenninger, Susanne (2015). Development of a quantitative PCR assay for rapid detection of Lactobacillus plantarum and Lactobacillus fermentum in cocoa bean fermentation. Journal of Microbiological Methods, 115 94-99. Peer reviewed.; ;
To monitor dominant species of lactic acid bacteria during cocoa bean fermentation, i.e. Lactobacillus plantarum and Lactobacillus fermentum, a fast and reliable culture-independent qPCR assay was developed. A modified DNA isolation procedure using a commercial kit followed by two species-specific qPCR assays resulted in 100% sensitivity for L. plantarum and L. fermentum. Kruskal–Wallis and post-hoc analyses of data obtained from experiments with cocoa beans that were artificially spiked with decimal concentrations of L. plantarum and L. fermentum strains allowed the calculation of a regression line suitable for the estimation of both species with a detection limit of 3 to 4 Log cells/g cocoa beans. This process was successfully tested for efficacy through the analyses of samples from laboratory-scale cocoa bean fermentations with both the qPCR assay and a culture-dependent method which resulted in comparable results.