Variability of Genetic Characters Associated with Probiotic Functions in Lacticaseibacillus Species

Abstract

This study aims to explore the intra-species distribution of genetic characteristics that favor the persistence in the gastrointestinal tract (GIT) and host interaction of bacteria belonging to species of the Lacticaseibacillus genus. These bacterial species comprise commercial probiotics with the widest use among consumers and strains naturally occurring in GIT and in fermented food. Since little is known about the distribution of genetic traits for adhesion capacity, polysaccharide production, biofilm formation, and utilization of substrates critically important for survival in GIT, which influence probiotic characteristics, a list of genetic determinants possibly involved in such functions was created by a search for specific genes involved in the above aspects in the genome of the extensively characterized probiotic L. rhamnosus GG. Eighty-two gene loci were retrieved and their presence and variability in other Lacticaseibacillus spp. genomes were assessed by alignment with the publicly available fully annotated genome sequences of L. casei, L. paracasei, L. rhamnosus, and L. zeae. Forty-nine of these genes were found to be absent in some strains or species. The remaining genes were conserved and covered almost all the functions considered, indicating that all strains of the genus may exert some probiotic effects. Among the variable loci, a taurine utilization operon and a α-L-fucosidase were examined for the presence/absence in 26 strains isolated from infant feces by PCR-based tests. Results were variable among the isolates, though their common origin indicated the capacity to survive in the intestinal niche. This study indicated that the capacity to exert probiotic actions of Lacticaseibacillus spp. depends on a conserved set of genes but variable genetic factors, whose role is only in part elucidated, are more numerous and can explain the enhanced probiotic characteristics for some strains. The selection of the most promising probiotic candidates to be used in food is feasible by analyzing the presence/absence of a set of variable traits.

In Vivo Functional Properties of Dairy Bacteria

“…The Lacticaseibacillus genus comprises different species able to exert probiotic functions with a variable asset of genes that confer probiotic activities [ 21 ]. L. paracasei is the species of non-starter LAB (NSLAB) most frequently isolated from cheeses of different types [ 7 , 22 , 23 , 24 ].…”

Special Issue “Functional Characterization of Lactic Acid Bacteria”: Editorial

“…However, individual strains have a variable capacity to exert beneficial effects, so that it could be useful to fix selection criteria for those with enhanced probiotic potential. An analysis of the fully annotated genomes of these species available from the GenBank database, 99 at the time of analysis, was carried out to identify gene loci encoding for characteristics involved in survival in GIT, adhesion to mucus or other host molecules, and production of cell-surface-associated macromolecules, including exopolysaccharides (EPS), involved in adhesion and immune stimulation [ 14 ]. Conserved genes include those encoding for a bile salt hydrolase, three surface antigens, proteins involved in the synthesis of LTA and teichoic acids, in biofilm formation and binding to mucus.…”