The bacterial family of Lactobacillaceae is constituted by two genera, Lactobacillus and Pediococcus, and includes a large number of species in which probiotic strains are recognised. Most of Lactobacillaceae species are grouped into 14 phylogenetic groups that are not coherent with the 3 traditional groups derived from the analysis of carbohydrate metabolism (homofermentative-A, facultatively-B, and obligately heterofermentative-C). The aim of this study was to apply, for the first time for this family, a genomic approach to find a consistency between phylogenetic and the genetic background related to metabolic data. The comparative analysis of the metabolic pathways involved in glucose metabolism (glycolysis and pentose phosphate pathway) performed on the 24 genomic sequences available, revealed genotypic differences typical for members of the 3 metabolic groups in term of presence/absence of 5 genes of glycolysis, namely the pyruvate dehydrogenase operon and phosphofructokinase. In silico predictions were then verified on every species of Lactobacillus delbrueckii and L. casei phylogenetic groups: the former includes members of the three different metabolisms (A, B and C), the latter only facultatively heterofermentative species (B). A genetic background typical of homofermentative (A) was revealed in L. delbrueckii species, despite their metabolic diversity, while gene content of L. casei species was typical of facultatively heterofermentative (B). This analysis showed that metabolic similarities among groups, i.e. facultatively heterofermentative members in both groups, were due to distinguishable genetic backgrounds. Moreover, from a genetic viewpoint, intra-group homogeneity and inter-group heterogeneity correlated with the phylogenetic subdivision, demonstrating the validity of the proposed approach to understand diversity and evolution of lactobacilli and related genera. These information, in the future, could also be used to refine the taxonomy of the family, which could have consequences also in nomenclature of probiotic species.

Unravelling the biodiversity of Lactobacillaceae family by comparative genomics

SALVETTI, Elisa;TORRIANI, Sandra;DELLAGLIO, Franco;FELIS, Giovanna
2011

Abstract

The bacterial family of Lactobacillaceae is constituted by two genera, Lactobacillus and Pediococcus, and includes a large number of species in which probiotic strains are recognised. Most of Lactobacillaceae species are grouped into 14 phylogenetic groups that are not coherent with the 3 traditional groups derived from the analysis of carbohydrate metabolism (homofermentative-A, facultatively-B, and obligately heterofermentative-C). The aim of this study was to apply, for the first time for this family, a genomic approach to find a consistency between phylogenetic and the genetic background related to metabolic data. The comparative analysis of the metabolic pathways involved in glucose metabolism (glycolysis and pentose phosphate pathway) performed on the 24 genomic sequences available, revealed genotypic differences typical for members of the 3 metabolic groups in term of presence/absence of 5 genes of glycolysis, namely the pyruvate dehydrogenase operon and phosphofructokinase. In silico predictions were then verified on every species of Lactobacillus delbrueckii and L. casei phylogenetic groups: the former includes members of the three different metabolisms (A, B and C), the latter only facultatively heterofermentative species (B). A genetic background typical of homofermentative (A) was revealed in L. delbrueckii species, despite their metabolic diversity, while gene content of L. casei species was typical of facultatively heterofermentative (B). This analysis showed that metabolic similarities among groups, i.e. facultatively heterofermentative members in both groups, were due to distinguishable genetic backgrounds. Moreover, from a genetic viewpoint, intra-group homogeneity and inter-group heterogeneity correlated with the phylogenetic subdivision, demonstrating the validity of the proposed approach to understand diversity and evolution of lactobacilli and related genera. These information, in the future, could also be used to refine the taxonomy of the family, which could have consequences also in nomenclature of probiotic species.
lactobacillus; taxonomy; comparative genomics; phylogeny
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11562/749972
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