Comparison of the Colonization Ability of Autochthonous and Allochthonous Strains of Lactobacilli in the Human Gastrointestinal Tract

Steven A Frese,Robert W Hutkins,Jens Walter

doi:10.4236/aim.2012.23051

Abstract

Bacteria of the genus Lactobacillus are widely used as oral probiotics due to their putative health benefits. In this study, we compared the colonization ability of two Lactobacillus strains that were identified as autochthonous to the human gastrointestinal tract (Lactobacillus reuteri ATCC PTA 6475 (MM4-1a) and Lactobacillus mucosae FSL-04) with that of an allochthonous strain (Lactobacillus acidophilus DDS-1). Colonization ability was tested in a single-blinded, cross-over study, with twelve human subjects. The test strains were quantified in fecal samples by two independent methods, selective plating and molecular typing and quantitative real time PCR. The study revealed that the two autochthonous strains (L. reuteri ATCC PTA 6475 and L. mucosae FSL-04) reached higher population levels in fecal samples and were recovered more frequently from subjects compared to the allochthonous strain (L. acidophilus DDS-1). All three strains became undetectable 8 days after the end of consumption with one exception, showing that persistence of all three strains remains short term in most individuals. In conclusion, this study showed that autochthonous Lactobacillus strains can be established more efficiently, albeit temporarily, in the human gastrointestinal tract, suggesting that evolutionary and ecological characteristics could be valuable criteria for the selection of probiotic strains.

Highlights

Probiotic bacteria are defined by the FAO/WHO “as live organisms which when administered in adequate amounts confer a health benefit to the host.” Implied in this definition is the expectation that these orally ingested organisms would reach the intestinal tract alive and at physiologically relevant levels [1]
The objective of this study was to test whether autochthonous Lactobacillus strains (L. mucosae FSL-04 and L. reuteri ATCC PTA 6475) can be established more efficiently in the human gastrointestinal tract than an allochthonous strain (L. acidophilus DDS-1) following a 7-day feeding period
Our findings indicate that the two autochthonous strains (L. reuteri ATCC PTA 6475 and L. mucosae FSL-04) reached higher populations and were generally more persistent than the allochthonous strain

Summary

Introduction

Probiotic bacteria are defined by the FAO/WHO “as live organisms which when administered in adequate amounts confer a health benefit to the host.” Implied in this definition is the expectation that these orally ingested organisms would reach the intestinal tract alive and at physiologically relevant levels [1]. Probiotic microorganisms are hypothesized to be functionally active in the human gut, such that they can influence the host through a variety of physiological mechanisms, including direct effects on the host immune system, in situ production of bioactive compounds, and competition with the resident microbiota and pathogens [2]. Some probiotic functions, such as in vivo production of bioactive compounds and competition with pathogens, require that probiotic bacteria are metabolically active in the human gut and competitive under the prevailing conditions. Even strains that are true autochthonous members of the microbiota of specific human subjects may not be able to colonize the gastrointestinal tract (GIT) of other humans due to individual differences [14]

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