The curated Lactobacillus acidophilus NCFM genome provides insights into strain specificity and microevolution.

Background: The advent of next generation sequencing technologies has enabled a surge in the number of whole genome sequences in public databases, and our understanding of the composition and evolution of bacterial genomes. Besides model organisms and pathogens, some attention has been dedicated to industrial bacteria, notably members of the Lactobacillaceae family that are commonly studied and formulated as probiotic bacteria. Of particular interest is Lactobacillus acidophilus NCFM, an extensively studied strain that has been widely commercialized for decades and is being used for the delivery of vaccines and therapeutics.

Results: Here, we revisit the L. acidophilus genome, which was sequenced twenty years ago, and determined the core and pan genomes of 114 publicly available L. acidophilus strains, spanning commercial isolates, academic strains and clones from the scientific literature. Results indicate a predictable high level of homogeneity within the species, but also reveal surprising mis-assemblies. Furthermore, by investigating twenty one available L. acidophilus NCFM-derived variants, we document overall genomic stability, with no observed genomic re-arrangement or inversions.

Conclusion: This study provides a comparative analysis of the currently available genomes for L. acidophilus and examines microevolution patterns for several strains derived from L. acidophilus NCFM, which revealed no to very few SNPs with strains sequenced at different points in time using different sequencing technologies and platforms. This re-affirms its suitability for industrial deployment as a probiotic and its use as an engineering chassis and delivery modality for novel biotherapeutics.