RT Journal Article SR Electronic(1) A1 Bottari, Benedetta A1 Felis, Giovanna E. A1 Salvetti, Elisa A1 Castioni, Anna A1 Campedelli, Ilenia A1 Torriani, Sandra A1 Bernini, Valentina A1 Gatti, MonicaYR 2017 T1 Effective identification of Lactobacillus casei group species: genome-based selection of the gene mutL as the target of a novel multiplex PCR assay JF Microbiology, VO 163 IS 7 SP 950 OP 960 DO https://doi.org/10.1099/mic.0.000497 PB Microbiology Society, SN 1465-2080, AB Lactobacillus casei, Lactobacillus paracasei and Lactobacillus rhamnosus form a closely related taxonomic group (the L. casei group) within the facultatively heterofermentative lactobacilli. Strains of these species have been used for a long time as probiotics in a wide range of products, and they represent the dominant species of nonstarter lactic acid bacteria in ripened cheeses, where they contribute to flavour development. The close genetic relationship among those species, as well as the similarity of biochemical properties of the strains, hinders the development of an adequate selective method to identify these bacteria. Despite this being a hot topic, as demonstrated by the large amount of literature about it, the results of different proposed identification methods are often ambiguous and unsatisfactory. The aim of this study was to develop a more robust species-specific identification assay for differentiating the species of the L. casei group. A taxonomy-driven comparative genomic analysis was carried out to select the potential target genes whose similarity could better reflect genome-wide diversity. The gene mutL appeared to be the most promising one and, therefore, a novel species-specific multiplex PCR assay was developed to rapidly and effectively distinguish L. casei, L. paracasei and L. rhamnosus strains. The analysis of a collection of 76 wild dairy isolates, previously identified as members of the L. casei group combining the results of multiple approaches, revealed that the novel designed primers, especially in combination with already existing ones, were able to improve the discrimination power at the species level and reveal previously undiscovered intraspecific biodiversity., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/mic.0.000497