Characterization of a novel Lactobacillus species closely related to Lactobacillus johnsonii using a combination of molecular and comparative genomics methods.
BACKGROUND
Comparative genomic hybridization (CGH) constitutes a powerful tool for identification and characterization of bacterial strains. In this study we have applied this technique for the characterization of a number of Lactobacillus strains isolated from the intestinal content of rats fed with a diet supplemented with sorbitol.


RESULTS
Phylogenetic analysis based on 16S rRNA gene, recA, pheS, pyrG and tuf sequences identified five bacterial strains isolated from the intestinal content of rats as belonging to the recently described Lactobacillus taiwanensis species. DNA-DNA hybridization experiments confirmed that these five strains are distinct but closely related to Lactobacillus johnsonii and Lactobacillus gasseri. A whole genome DNA microarray designed for the probiotic L. johnsonii strain NCC533 was used for CGH analysis of L. johnsonii ATCC 33200T, L. johnsonii BL261, L. gasseri ATCC 33323T and L. taiwanensis BL263. In these experiments, the fluorescence ratio distributions obtained with L. taiwanensis and L. gasseri showed characteristic inter-species profiles. The percentage of conserved L. johnsonii NCC533 genes was about 83% in the L. johnsonii strains comparisons and decreased to 51% and 47% for L. taiwanensis and L. gasseri, respectively. These results confirmed the separate status of L. taiwanensis from L. johnsonii at the level of species, and also that L. taiwanensis is closer to L. johnsonii than L. gasseri is to L. johnsonii.


CONCLUSIONS
Conventional taxonomic analyses and microarray-based CGH analysis have been used for the identification and characterization of the newly species L. taiwanensis. The microarray-based CGH technology has been shown as a remarkable tool for the identification and fine discrimination between phylogenetically close species, and additionally provided insight into the adaptation of the strain L. taiwanensis BL263 to its ecological niche.
Sarmiento-Rubiano
Luz-Adriana
LA
Laboratorio de Bacterias Lácticas y Probióticos, IATA-CSIC, PO Box 73, 46100 Burjassot, Valencia, Spain.
Berger
Bernard
B
Moine
Déborah
D
Zúñiga
Manuel
M
Pérez-Martínez
Gaspar
G
Yebra
María J
MJ
D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D055028:Comparative Genomic Hybridization / Q000379:methods*; D017124:Conserved Sequence / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D015964:Gene Expression Regulation, Bacterial; D056426:Genetic Loci / Q000235:genetics; D016680:Genome, Bacterial / Q000235:genetics*; D023281:Genomics / Q000379:methods*; D007778:Lactobacillus / Q000235:genetics* / Q000302:isolation & purification; D009693:Nucleic Acid Hybridization; D020411:Oligonucleotide Array Sequence Analysis; D010641:Phenotype; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D051381:Rats; D015203:Reproducibility of Results; D017422:Sequence Analysis, DNA; D013045:Species Specificity
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S