Intraspecific Genotypic Characterization of Lactobacillus rhamnosus Strains Intended for Probiotic Use and Isolates of Human Origin

Abstract

A set of 118 strains of the species Lactobacillus rhamnosus was collected, including probiotic strains, research strains with potential probiotic properties, food starter cultures, and human isolates. The majority of the strains were collected from companies, hospitals, or culture collections or were obtained after contacting authors who reported clinical case studies in the literature. The present work aimed to reveal the genotypic relationships between strains of these diverse sources. All strains were initially investigated using fluorescent amplified fragment length polymorphism (FAFLP) with three different primer combinations. Numerical analysis of FAFLP data allowed (i) confirmation of the identification of all strains as members of L. rhamnosus and (ii) delineation of seven stable intraspecific FAFLP clusters. Most of these clusters contained both (potentially) probiotic strains and isolates of human origin. For each of the clusters, strains of different sources were selected for pulsed-field gel electrophoresis (PFGE) of macrorestriction fragments obtained with the enzymes NotI and AscI. Analysis of PFGE data indicated that (i) some (potentially) probiotic strains were indistinguishable from other probiotic strains, suggesting that several companies may use duplicate cultures of the same probiotic strain, and (ii) in a number of cases human isolates from sterile body sites were indistinguishable from a particular probiotic strain, suggesting that some of these isolates may be reisolations of commercial strains.Lactobacillus species are members of the commensal microflora in the oral cavity and the gastrointestinal and genitourinary system in humans and animals and are usually considered nonpathogenic (1). Selected strains of some Lactobacillus species are being used as probiotics and are claimed to influence the health of the host in a beneficial manner (10). To a very limited extent, strains belonging to the same Lactobacillus species as those used in probiotic applications have also been isolated from clinical specimens and have been associated with rare cases of endocarditis, meningitis, deep abscesses, and bacteremia (1, 5, 11). It should be noted that in these types of infections underlying disease or immunosuppression is a common feature and that infection in previously healthy humans is extremely rare.Among the lactobacilli, strains of Lactobacillus rhamnosus are commonly used as probiotics including the GG (GorbachGoldin) strain, which is one of the most widely used and welldocumented probiotics (13, 25). On the other hand, L. rhamnosus has also been reported as one of the most common Lactobacillus taxa in human clinical cases (5). Harty et al. (8,9) identified possible virulence factors in L. rhamnosus endocarditis strains compared to laboratory or oral isolates. Furthermore, L. rhamnosus strains have been shown to produce enzymes enabling the breakdown of glycoproteins and synthesis or lysis of fibrin clots (18).Aggregate epidemiologic studies have not found a link between the number of clinica...

Bacteroides fragilis polysaccharide A is necessary and sufficient for acute activation of intestinal sensory neurons

“…An independent laboratory, the Bacteria Collection Laboratory for Microbiology, University of Ghent, Belgium has further confirmed it to be a rhamnosus using DNA fingerprinting by the AFLP technique. This laboratory was unable to assign the L. rhamnosus (JB-1) to any of the seven intra-specific clusters they have previously reported among 118 strains of this species from around the world 52 and specific comparison with L. rhamnosus (GG) has shown significant differences between these bacteria 8 . All journals in which this wrongly ascribed bacterium has been identified have been asked to publish an erratum or corrigendum containing these facts.…”

Scientific Opinion on the substantiation of health claims related to Lactobacillus rhamnosus LB21 NCIMB 40564 and decreasing potentially pathogenic intestinal microorganisms (ID 1064), digestive health (ID 1064), and reduction of mutans streptococci in the oral cavity (ID 1064) pursuant to Article 13(1) of Regulation (EC) No 1924/2006

“…The Panel considers that the claim does not comply with the criteria laid down in Regulation (EC) No 1924No /2006.…”

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European Food Safety Authority (EFSA), Parma, Italy

SUMMARYFollowing a request from the European Commission, the Panel on Dietetic Products, Nutrition and Allergies was asked to provide a scientific opinion on a list of health claims pursuant to Article 13 of Regulation (EC) No 1924No /2006. This opinion addresses the scientific substantiation of health claims in relation to Lactobacillus rhamnosus LB21 NCIMB 40564 and decreasing potentially pathogenic intestinal microorganisms, "digestive health", and reduction of mutans streptococci in the oral cavity.

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Genetic tools for investigating the biology of commensal lactobacilli

“…The choice of application of these approaches mainly depends on the requirement for differentiation. Methods based on whole genome polymorphisms such as renaturing SDS-PAGE (72), pulsed-field gel electrophoresis (PFGE) (73), amplified fragment length polymorphism (AFLP) (74) and temporal temperature gradient gel electrophoresis (TTGE) (75) are also useful to determine the relatedness of Lactobacillus isolates.…”