Systemy komunikacji miȩdzykomórkowej bakterii gram-ujemnych i ich znaczenie w ekspresji cech fenotypowych

The expression of bacterial phenotype depends on the number of cells. That phenomenon is termed as quorum sensing. The quorum sensing is regulated by the freely diffusing, low molecular mass components. The Gram-negative bacteria utilize the derivatives of the homoserine lactones (acyl-HSL). The acyl-HSL are composed of homoserine lactone and fatty acids of different lengths. Acyl-HSL by binding regulatory proteins influence bioluminescence of Vibrio fisheri roods. In many cases the quorum sensing systems are multilevel, e.g. Pseudomonas aeruginosa (las, rhl, PQS - 2-heptyl-3-hydroxy-4-quinolone). The P. aeruginosa quorum sensing is responsible for the production of such pathogenic agents as toxins (exotoxin A), proteases (elastase, LasA protease and alkaline protease), polysaccharides and hemolysins (rhamnolipid and phospholipase). The listed pathogenic factors are responsible for complications in patients suffering from cystic fibrosis (CF). The features of fitopathogenic bacteria (Agrobacterium tumefaciens, Burkholderia cepacia, Ervinia carotovora) and biofilm formation are also regulated by acyl-HSL.