Molecular phylogeny and comparative genomics of Gram- positive bacteria of the gastrointestinal tract / Filogenia molecular e genômica comparativa de bactérias Grampositivas do trato gastrointestinal

AUTOR(ES)

Daniele Ferreira da Silva

DATA DE PUBLICAÇÃO

2007

RESUMO

Recent information on the complete genome of probiotic lactic acid bacteria and Listeria monocytogenes, and the elucidation on those caused on large clusters of virulence genes, denominated pathogenicity islands (PAIs) present in L. monocytogenes, have brought the attention to the likely existence of gene sequences common to both groups, probiotic and enteropathogenic bacteria, as well as of similar genes that are only activated in the gastrointestinal tract. This work aimed to evaluate by means of comparative genomics the similarities and differences among genes encoding virulence proteins in L. monocytogenes EGD-e and those encoding probiotic functions in probiotic Lactobacillus, and also to isolate and characterize the clp stress resistance gene in Lactobacillus delbrueckii UFV H2b20. The genes sequences were captured from the databank of the National Center for Biotechnology Information (NCBI) and for each gene a homology search was performed using the program BLASTp, and an orthology search, using the program Clusters of Orthologous Groups (COG). The homologous and orthologous genes were selected from genome sequences of Listeria innocua CLIP1162, Lactobacillus acidophilus NCFM, Lactobacillus plantarum WCFS1, Lactobacillus johnsonii NC 533, Lactobacillus gasseri ATCC33233, Lactobacillus salivarius subsp. salivarius UCC118, Lactobacillus reuteri F275, Lactobacillus delbrueckii subsp. bulgaricus ATCC BAA-365 and Lactobacillus delbrueckii subsp. bulgaricus ATCC 11842.The analysis of the phylogenetic trees reconstructed based on higher interest genes reinforces the hypothesis that a parallel may be made to some extent between the pathogenic and the probiotic responses. The probiotic LABs present genes fundamentally important for probiosis that are absent in the pathogen L. monocytogenes, as are most of the genes involved in the mechanism of adhesion. The existence of the clp gene was confirmed in L. delbrueckii UFV H2b20, with the homologous genes encoding proteins of the proteolytic complex Clp presenting high percentage of identity and similarity. Among the best homologous genes is the gene clpC present in various lactobacili. From a L. delbrueckii UFV H2b20 library, several phages were tested positive for clp. Possibly, more than one subunit of this proteolytic complex was identified, as the DNA probe hybridized with several of these subunits genes. Confirmation of the presence in L. delbrueckii UFV H2b20 and functional analysis of other genes already identified in probiotic LABs genomes will demand a comparative analysis of the functions of such genes in other probiotic strains, to justify the importance of L. delbrueckii UFV H2b20 in health and for food bio-processing.

ASSUNTO(S)

filogenia molecular bactérias do ácido lático probiotic genômica comparativa ciencia de alimentos molecular phylogeny probióticos lactic acid bacteria listeria monocytogenes comparative genomics listeria monocytogenes

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