PCR-fingerprinting methods analysis have also been used to Temozolomide examine the strain diversity of Lactobacillus probiotics. For example, Schillinger et al. [8] used Random Amplified Polymorphic DNA (RAPD) analysis to differentiate Lactobacillus strains cultivated from probiotic yogurts. Pena et al[9] used Repetitive Element PCR (REP) profiling to examine the genetic diversity of intestinal Lactobacillus species colonising different transgenic mouse-lines; they demonstrated that mice with colitis due to IL-10 deficiency

were colonised with a different population of strains in comparison to those without colitis. Multilocus sequence typing, a very powerful nucleotide sequence based strain differentiation methods has also been recently developed for Lactobacillus plantarum [10] and Lactobacillus casei [11]. However, genetic typing methods that work at the strain level have seen limited use in their direct application to the human gut microbiota eFT508 cost and have not yet been applied to specifically track the fate of a specific probiotic strain during consumption. Understanding the dynamics of gut colonisation by bacterial probiotics

is an important parameter for the future clinical development of these therapeutic agents. We set out to determine if individual Lactobacillus species strains could be tracked after human consumption of the encapsulated bacteria. RAPD was selected as a suitable strain typing method to answer this question because: (i) as a PCR-based method it was Selleckchem LEE011 amenable to high throughput, and, (ii) we knew from past-experience that if the RAPD method was systematically developed to target specific bacterial

species, then its discriminatory power can be comparable to state-of-the-art DNA sequence-based genotyping methods such L-gulonolactone oxidase as multilocus sequence typing [12]. Here we describe the systematic development of a RAPD fingerprinting method for a broad range of LAB species and its optimization to allow direct application to single bacterial colonies. Using this novel high throughput colony strain typing strategy we were then able for the first time to track the fate of specific Lactobacillus strains after their consumption by human volunteers. Results Development of a RAPD fingerprinting method for Lactic Acid Bacteria To systematically develop a RAPD typing scheme for LAB species, a set of 100 RAPD primers which had proven successful for strain typing other bacterial species [13, 14] were screened for their ability to amplify multiple polymorphisms from L. acidophilus. Fifteen primers (Table 1) were found to reproducibly amplify 8 or more random DNA fragments from the reference strain L. acidophilus LMG 9433T that ranged in size from 200 to 4000 bp (Fig. 1). The complexity of these profiles indicated that discriminatory typing of LAB isolates with these primers was possible.