SRA

Lactobacillus rhamnosus GG has become one of the most widely marketed and studied probiotic strains. Several genes important for probiotic function have been identified, including the spaCBA-srtC1 gene cluster encoding pili, which have been shown to be important for certain of its probiotic properties. The spaCBA-srtC1 gene cluster has been reported to be unstable in L. rhamnosus GG isolated from liquid dairy products and therefore the present study examined the L. rhamnosus GG genome stability throughout an industrial production process from the original deposit to the freeze-dried products including intermediate fermentations and single colony isolates prepared from these samples. The results showed that the original deposit was identical to the reference ATCC and that the genome sequence stayed fully intact throughout the production process. No SNPs or larger genomic changes occurred in any of the samples throughout the production process and the spaCBA-srtC1 gene locus was fully conserved and intact in all 31 samples examined. In addition, phenotypic expression of pili was demonstrated using immune-gold labelling EM. The images showed that pili production was preserved throughout the production process and that the number of pili were consistent in all batches. The present study extends the scope of previous findings to an industrial setting and shows that the region around the spaCBA-srtC1 cluster exhibits high stability in L. rhamnosus GG in an industrial production process. Overall design: Genome sequencing of 37 Lactobacillus rhamnosus GG samples from Chr.Hansen