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Communication and competition between grampositive bacteria that produce...

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Titel Communication and competition between grampositive bacteria that produce peptide pheromones in the gastro-intestinal tract
Looptijd 10 / 1999 - 10 / 2003
Status Afgesloten
Dissertatie Ja
Onderzoeknummer OND1309799

Samenvatting (EN)

Quorum sensing is a cell-density dependent regulatory system. In this system, bacteria secrete pheromone molecules which accumulate outside of the cell. Individual cells are able to sense how many neighbouring cells surround them by sensing the concentration of these pheromones. In this manner, bacteria communicate with each other by using these pheromones. In Gram-positive bacteria it was shown that these pheromones were of a peptide nature. This QS-mechanism also seems to have a function in survival in a competitive environment in nature. For example in several lactic acid bacteria, production of some antimicrobial peptides (AMPs), so-called "bacteriocins", are activated by quorum sensing. When these bacteria live in dense populations, they produce bacteriocins to prevent the invasion of other bacteria. Also the development of genetic competence (ability to "pick up" DNA) or virulence in some bacteria is dependent on quorum sensing. Since the animal gut includes a high density of micro-organisms consisting mainly of Gram-positive bacteria, we think that a significant part of these bacteria use quorum sensing mechanisms involving peptide pheromones. Knowledge about these mechanisms should help us to understand how bacteria communicate with each other in the human GI-tract.
[Approach]:
A large part of the bacteria in the human gut is difficult to culture (approximately only 20 % is culturable). Thus, we mainly take a genetic approach in which genes involved in quorum sensing (so called "communication modules") are being amplified by a degenerate PCR method on total DNA extracted from human feces. Using this genetic approach, the presence, sequence and diversity of quorum sensing systems in the human gut can be analysed without a bias resulting from culturing steps. These analyses are being done on fecal samples from several volunteers. The final goal of this study is to find out which quorum sensing systems are dominantly present in the GI-tract, which Gram-positive bacteria are expressing these genes and how these bacteria use quorum sensing systems for communication and competition

Betrokken organisaties

Betrokken personen

Promotor Prof.dr. W.M. de Vos
Onderzoeker Dr.ir. M.H.J. Sturme
Projectleider Dr. E.E. Vaughan

Classificatie

A90000 Zuiver-wetenschappelijk onderzoek
D22100 Microbiologie

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