Direct Application of Rep-PCR on Type I Sourdough Matrix to Monitor the Dominance and Persistence of a Lactobacillus plantarum Starter Throughout Back-Slopping

This study describes the optimization and application of repetitive element-PCR (rep-PCR) technique directly on microbial DNA extracted from type I sourdoughs for fast monitoring of a L. plantarum starter strain (P1FMC) throughout daily back-slopping, in response to pratical needs of a bakery factory. Co-inoculum trials, in flour matrix, with L. plantarum P1FMC and L. lactis LC71 strains and, subsequently, type I sourdough back-slopping trials were performed. The rep-PCR amplification profiles obtained were clearly referable to that of Lb. plantarum P1FMC starter in both co-inoculum trials (also when it was present with one order of magnitude less with respect to L. lactis LC71) and back-slopping trials where it dominated the fermentation process with loads of 108 cfu g-1 and prevailed on the autochthonous microbiota. Thus, the approach proposed in this paper could be considered a methodological advancement, based on a culture-independent one-step rep-PCR, suitable for fast monitoring of starter performance.