title: Genetic diversity of Lactobacillus paracasei isolated from in situ human oral biofilms.
abstract: OBJECTIVE
  To determine the genetic diversity and possible origin of Lactobacillus paracasei found in the oral biofilm.
  
  
  RESULTS
  Lactobacilli were isolated from a biofilm model, formed in situ prior to and during a period of exposure to 20% sucrose solution (28 days), using Rogosa Agar. The lactobacillus colonies were randomly selected (n = 222) and subcultured. The isolates were identified using pheS or rpoA gene sequence analysis. Lactobacilli identified as Lact. paracasei (n = 75) were subjected to multilocus sequencing typing (MLST) analysis by determining partial sequences of seven housekeeping genes fusA, ileS, lepA, leuS, pyrG, recA and recG. An increase recovery of lactobacilli after sucrose phase compared with nonsucrose period was observed (31 prior to and 191 following a sucrose exposure period). Seven subjects harboured Lact. paracasei and these represented 14 sequence types (ST). Comparison of the STs showed that unrelated subjects may harbour the same ST and that individuals harbour multiple STs. Three subjects harboured STs previously isolated from dairy products.
  
  
  CONCLUSIONS
  The present data supports the hypothesis that oral lactobacilli may be of exogenous origin.
  
  
  CONCLUSIONS
  The study allow us to gain insight into the genetic diversity of Lact. paracasei in oral biofilm.
authors.affiliation: Department of Social and Preventive Dentistry, Faculty of Dentistry, Federal University of Rio Grande do Sul, Porto Alegre, Brazil. fatturiparolo@yahoo.com
authors.forename: C C F
authors.initials: CC
authors.lastname: Parolo
authors.forename: T
authors.initials: T
authors.lastname: Do
authors.forename: U
authors.initials: U
authors.lastname: Henssge
authors.forename: L S
authors.initials: LS
authors.lastname: Alves
authors.forename: F C M
authors.initials: FC
authors.lastname: de Santana Giongo
authors.forename: G
authors.initials: G
authors.lastname: Corção
authors.forename: M
authors.initials: M
authors.lastname: Maltz
authors.forename: D
authors.initials: D
authors.lastname: Beighton
mesh_terms: D015373:Bacterial Typing Techniques / Q000379:methods; D018441:Biofilms; D014644:Genetic Variation; D006801:Humans; D007778:Lactobacillus / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D013395:Sucrose / Q000378:metabolism; D014070:Tooth / Q000382:microbiology*
chemical_list: D013395:Sucrose