title: Strain-specific detection of orally administered canine jejunum-dominated Lactobacillus acidophilus LAB20 in dog faeces by real-time PCR targeted to the novel surface layer protein.
abstract: Lactobacillus acidophilus LAB20 has potential to be a probiotic strain because it can be present at high numbers in the jejunum of dog. To specifically detect LAB20 from dog faecal samples, a real-time PCR protocol was developed targeting the novel surface (S) layer protein gene of LAB20. The presence of S-layer protein was verified by N-terminal sequencing of the approximately 50-kDa major band from SDS-PAGE gel. The corresponding S-layer gene was amplified by inverse PCR using homology to known S-layers and sequenced. This novel S-layer protein has low sequence similarity to other S-layer proteins in the N-terminal region (32-211 aa, 7-39%). This enabled designing strain-specific PCR primers. The primer set was utilized to study intestinal persistence of LAB20 in dog that was fed with LAB20 fermented milk for 5 days. The results showed that LAB20 can be detected from dog faecal sample after 6 weeks with 10(4·53)  DNA copies g(-1) postadministration. It suggested that LAB20 could be a good candidate to study the mechanism behind its persistence and dominance in dog intestine and maybe utilize it as a probiotic for canine.
  
  
  CONCLUSIONS
  A real-time PCR method was developed to detect Lactobacillus acidophilus LAB20, a strain that was previously found dominant in canine gastrointestinal (GI) tract. The quantitative detection was based on targeting to variation region of a novel S-layer protein found in LAB20, allowing to specifically enumerate LAB20 from dog faeces. The results showed that the real-time PCR method was sensitive enough to be used in later intervention studies. Interestingly, LAB20 was found to persist in dog GI tract for 6 weeks. Therefore, LAB20 could be a good candidate to study its colonization and potentially utilize as a canine probiotic.
authors.affiliation: Department of Food and Environmental Sciences, University of Helsinki, Helsinki, Finland.
authors.forename: Y
authors.initials: Y
authors.lastname: Tang
authors.forename: P E J
authors.initials: PE
authors.lastname: Saris
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics*; D017931:DNA Primers / Q000235:genetics; D004285:Dogs; D005243:Feces / Q000382:microbiology*; D041981:Gastrointestinal Tract / Q000382:microbiology; D007583:Jejunum / Q000382:microbiology*; D007779:Lactobacillus acidophilus / Q000235:genetics / Q000302:isolation & purification*; D008562:Membrane Glycoproteins / Q000235:genetics*; D019936:Probiotics / Q000008:administration & dosage* / Q000302:isolation & purification; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods*; D013045:Species Specificity
chemical_list: D001426:Bacterial Proteins; D017931:DNA Primers; D008562:Membrane Glycoproteins; C055764:S-layer proteins
keywords: Lactobacillus acidophilus; S-layer protein; dog; real-time PCR