title: Indication for Co-evolution of Lactobacillus johnsonii with its hosts.
abstract: BACKGROUND
  The intestinal microbiota, composed of complex bacterial populations, is host-specific and affected by environmental factors as well as host genetics. One important bacterial group is the lactic acid bacteria (LAB), which include many health-promoting strains. Here, we studied the genetic variation within a potentially probiotic LAB species, Lactobacillus johnsonii, isolated from various hosts.
  
  
  RESULTS
  A wide survey of 104 fecal samples was carried out for the isolation of L. johnsonii. As part of the isolation procedure, terminal restriction fragment length polymorphism (tRFLP) was performed to identify L. johnsonii within a selected narrow spectrum of fecal LAB. The tRFLP results showed host specificity of two bacterial species, the Enterococcus faecium species cluster and Lactobacillus intestinalis, to different host taxonomic groups while the appearance of L. johnsonii and E. faecalis was not correlated with any taxonomic group. The survey ultimately resulted in the isolation of L. johnsonii from few host species. The genetic variation among the 47 L. johnsonii strains isolated from the various hosts was analyzed based on variation at simple sequence repeats (SSR) loci and multi-locus sequence typing (MLST) of conserved hypothetical genes. The genetic relationships among the strains inferred by each of the methods were similar, revealing three different clusters of L. johnsonii strains, each cluster consisting of strains from a different host, i.e. chickens, humans or mice.
  
  
  CONCLUSIONS
  Our typing results support phylogenetic separation of L. johnsonii strains isolated from different animal hosts, suggesting specificity of L. johnsonii strains to their hosts. Taken together with the tRFLP results, that indicated the association of specific LAB species with the host taxonomy, our study supports co-evolution of the host and its intestinal lactic acid bacteria.
authors: Department of Biotechnology and Food Engineering, Technion-Israel Institute of Technology, Haifa, Israel.
authors: Keren
authors: K
authors: Buhnik-Rosenblau
authors: Vera
authors: V
authors: Matsko-Efimov
authors: Minju
authors: M
authors: Jung
authors: Heuynkil
authors: H
authors: Shin
authors: Yael
authors: Y
authors: Danin-Poleg
authors: Yechezkel
authors: Y
authors: Kashi
mesh_terms: D000818:Animals; D019143:Evolution, Molecular; D005243:Feces / Q000382:microbiology*; D014644:Genetic Variation; D006801:Humans; D007778:Lactobacillus / Q000235:genetics* / Q000302:isolation & purification; D008969:Molecular Sequence Data; D058885:Multilocus Sequence Typing; D012150:Polymorphism, Restriction Fragment Length; D017422:Sequence Analysis, DNA