Identification of intestinal lactobacilli by automated ribotyping and MALDI-TOF MS
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| Year of publication | 2010 |
| Type | Conference abstract |
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| Description | The human gastrointestinal tract contains a diverse microbial community. Among them lactobacilli are important members of the natural intestinal microbiota playing a beneficial role in balancing of the intestinal environment. A collection of 51 Lactobacillus isolates originating from children intestinal mucous tissues has been studied. Analysed biopsy samples were retrieved during a routine endoscopic examination of different parts of the large intestine in patients revealing various disorders. A combined approach, which included automated ribotyping and MALDI-TOF MS analysis, was applied for identification of isolated Lactobacillus spp. in order to compare the discriminatory power of these methods. Automated ribotyping using the RiboPrinter Microbial Characterization System (DuPont Qualicon) assigned 38 lactobacilli to the species level: Lactobacillus salivarius (29 isolates), Lactobacillus paracasei subsp. paracasei (7) and Lactobacillus rhamnosus (2). The remaining 13 isolates were not identified due to low degree of similarity (85% threshold) with the reference ribotype patterns. Additional cluster analysis of the ribotype patterns was performed by BioNumerics v. 6.0 software (Applied-Maths) and enabled to assign 10 isolates as L. salivarius. Three remaining strains were not identified by the RiboPrinter/BioNumerics approach. MALDI-TOF MS analysis was performed on an Ultraflex III instrument (Bruker Daltonik) according to a standard sample preparation protocol of Bruker Daltonik. MALDI-TOF mass spectra were subjected to numerical analysis (BioTyper 1.1 software, Bruker Daltonik), which revealed the formation of a cluster harbouring all 39 isolates identified as L. salivarius and identified all L. paracaseii and L. rhamnosus isolates being separated in species-specific clusters in agreement with the ribotyping results. Three isolates unidentified with the RiboPrinter system were assigned as Lactobacillus mucosae by the MALDI-TOF MS. In conclusion, the MALDI-TOF MS enabled reliable identification of all analysed Lactobacillus isolates to the species level. In contrast, automatic identification performed by the RiboPrinter system did not identify 10 L. salivarius and all L. mucosae isolates. Supported by the projects of the Ministry of Education, Youth and Sports of the Czech Republic (2B08068, LC06034, MSM0021622415 and MSM0021622416). |
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