CH4 - Physiological regulation of microbial biofilm formation on solid surfaces by cellular signalling compounds and effects of volatile metabolites on corrosion

• Research unit: COST
• Project number: C98.0017

Key words (English)

Biofilm formation; microbial corrosion; cellular signaling; quorum sensing

Research programs (English)

COST-Action 520 - Biofouling et matériaux

Short description (English)

See abstract

Partners and International Organizations (English)

B, DK, FIN, F, D, GR, H, I, NL, P, RO, SI, E, S, CH, GB

Abstract (English)

Bacteria are not hermits. It is widely accepted that bacteria do not exist as solitary cells but rather as a population of cells communicating with cell-to-cell signaling compounds. Microorganisms achieve synchronous physiological changes and adaptations to environmental changes. Releasing chemical signal molecules in a function of cell density they can sense their immediate neighborhood, an effect called quorum sensing. The detection and monitoring of signalling molecules by bacteria is regarded as an important process in biofilms where cell densities are usually high. The earliest findings of such chemicals have been made with gram-negative microorganisms where the most common signaling molecules are the N-acyl homoserine lactones. The range of physiological reactions to quorum sensing signals can include biofilm formation, virulence, conjugation, antibiotic production and motility, to name few. Understanding the mechanisms and molecules involved in these processes is regarded as a possibility towards the control of biofilm formation. The finding of molecules being able to interfere with quorum sensing in Gram-negatives has boosted such hope in recent years. Furanones analogues to natural inducers are a promising group of chemicals for future applications in the control of cell-to-cell signaling dependent processes. We have examined a large variety of furanones (chemically synthesized and obtained form the University of Basel) for their ability to interfere with the quorum sensing mechanisms using a quantitative bioassay with Chromobacterium violaceum. All the furanones tested interacted in some way with growth and pigment formation in C. violaceum. Generally, homoserine lactones with long side chains (C10-C10) inhibit at low and induce at higher concentrations while those with short side chains (C4-C8) have opposite effects. However, from the results it is difficult to deduce a general structure function relationship. It must be emphasized that when compounds interacting with the quorum sensing system are studied, it is crucial to observe effects over a broad range of concentrations, because also natural inducers may act as inhibitors or - in turn - inhibitors are able to activate the system.

References in databases (English)

Swiss Database: COST-DB of the State Secretariat for Education and Research Hallwylstrasse 4 CH-3003 Berne, Switzerland Tel. [phone] Swiss Project-Number: C98.0017