title: [Quorum-sensing behavior of Lactobacillus paracasei HD1.7].
abstract: OBJECTIVE
  Paracin 1.7 was a bacteriocin extracted from Lactobacillus paracasei HD1.7. In this study, we investigated quorum-sensing mechanism that regulates the metabolism of Paracin 1.7 in strain HD1.7.
  
  
  METHODS
  The antibacterial activity of strain HD1.7 under different growth conditions was analyzed using an agar-well diffusion method, and the cell density was controlled by adjusting nutrient levels in the culture medium.
  
  
  RESULTS
  The antibacterial activity of strain HD1.7 depended on cell density. Strain HD1.7 exhibited the antibacterial activity when the cell density reached a threshold (OD600 of 0.8 and cell dried weight of 0.3311 g/L). Addition of different concentrations of a signaling molecule in the supernatant of the fermentation broth affected the antibacterial activity. After removing the signal molecule, the antibacterial activity was significantly decreased.
  
  
  CONCLUSIONS
  Paracin1.7 was the quorum-sensing signaling molecule in the HD1.7 fermentation broth and it could be auto-induced. The antibacterial activity of Paracin1.7 was regulated by the quorum-sensing system in HD1.7.
authors.affiliation: Key Laboratory of Microbiology of Heilongjiang Province, Life Science College, Heilongjiang University, Harbin 150080, China. gejingping@126.com
authors.forename: Jingping
authors.initials: J
authors.lastname: Ge
authors.forename: Baozhu
authors.initials: B
authors.lastname: Fang
authors.forename: Tingting
authors.initials: T
authors.lastname: Yuan
authors.forename: Wenxiang
authors.initials: W
authors.lastname: Ping
mesh_terms: D000900:Anti-Bacterial Agents / Q000378:metabolism; D001430:Bacteriocins / Q000378:metabolism*; D002450:Cell Communication / Q000502:physiology; D007778:Lactobacillus / Q000378:metabolism / Q000502:physiology*; D053038:Quorum Sensing / Q000502:physiology*; D015398:Signal Transduction
chemical_list: D000900:Anti-Bacterial Agents; D001430:Bacteriocins