N-Acylhomoserine lactone acylase (AHL acylase) is a well-known enzyme responsible for disrupting cell-cell communication (quorum sensing) in bacteria. Here, we isolated and characterized a novel and unique AHL acylase (designated MacQ) from a multidrug-resistant bacterium, Acidovorax sp. strain MR-S7. The purified MacQ protein heterologously expressed in Escherichia coli degraded a wide variety...

Pseudomonas aeruginosa is an opportunistic, nosocomial pathogen for which antibiotic resistance and biofilm development is common. Quorum sensing communication is known to be a major controlling factor in virulence gene expression, biofilm development, antibiotic resistance factors, and specifically MexAB-OprM multi-drug efflux pump expression in P.aeruginosa. MexAB-OprM efflux pumps contribute...

The large repABC plasmids of the order Rhizobiales with Class I quorum-regulated conjugative transfer systems often define the nature of the bacterium that harbors them. These otherwise diverse plasmids contain a core of highly conserved genes for replication and conjugation raising the question of their evolutionary relationships. In an analysis of 18 such plasmids these elements fall into two...

Quorum sensing is a process of intercellular communication. It allows individual cells to assess population density and to co-ordinate behaviour by secreting and sensing communication molecules. In the yeast Saccharomyces cerevisiae, the communication molecules are the aromatic alcohols tryptophol and phenylethanol, and quorum sensing regulates the transition between the solitary yeast form and...

As a ubiquitous environmental organism and an important human pathogen, Pseudomonas aeruginosa readily adapts and responds to a wide range of conditions and habitats. The intricate regulatory networks that link quorum sensing and other global regulators allow P. aeruginosa to coordinate its gene expression and cell signaling in response to different growth conditions and stressors. Upon nutrien...

Replication is a key factor for improving the availability and reliability of data in a distributed database system. A Major restriction is that replicated copies should behave like a single copy. Many replica control algorithms have been proposed for solving the problem, but the performance of various replica control algorithms has received relatively little attention. In this paper, the perfo...

We propose a simple model to compute the probability of success under a quorum sensing strategy. We show that a quorum sensing strategy has a higher probability of success than an individualistic strategy when, for instance, the probability of success for a single individual is low and the cost of building a quorum is not too high. On the other hand if the cost of building a quorum is too high ...

Designing efficient and fault-tolerant algorithms for solving the mutual exclusion problem is an important issue in distributed systems. Many algorithms have been proposed in the literature, and they are being broadly classified into two types: token-based and permissionbased [5, 21]. In a token-based algorithm, the system uses a unique token to represent the privilege for the node possessing i...

Nosocomial infections caused by Staphylococcus epidermidis are characterized by biofilm formation on implanted medical devices. Quorum-sensing regulation plays a major role in the biofilm development of many bacterial pathogens. Here, we describe luxS, a quorum-sensing system in staphylococci that has a significant impact on biofilm development and virulence. We constructed an isogenic Deltalux...

AIMS Experiments were designed to detect quorum-sensing signals produced by Clostridium botulinum. METHODS AND RESULTS Clostridium botulinum 56A cell-free supernatants obtained at the end of lag phase, the mid-exponential phase and early stationary phase of growth were assayed for bioluminescence in the Vibrio harveyi quorum-sensing assay system. Twelve and 16-h culture supernatants induced b...