Özet:

It has become increasingly and widely recognised that bacteria do not exist as solitary cells, but are colonial organisms that exploit elaborate systems of intercellular communication to facilitate their adaptation to changing environmental conditions Many types of signalling molecules, which regulate diverse phenotypes across distant genera.The most common signalling molecules found in Gram-negative bacteria are N-acyl derivatives of homoserine lactone (acyl HSLs), P.aeruginosa and K.pneumoniae can regulate different group actives and physiological processes through the quorum sensing mechanism. The aims of this research were to detect the presence of quorum sensing genes in ten clinical isolates of P. aeruginosa and ten clinical isolates of k.pneumoniae which represent by (pqsA,pqsR1, lasR,Luxs,LsrR and Lsrk genes)respectively by Polymerase chain reaction (PCR),Result: The DNA of 20 P. aeruginosa and k.pneumoniae isolates were successfully extracted with g-spin DNA extraction kit, the detection of pqsA,pqsR1 and lasR genes showed that all of the 10 isolates under study were positive for one or more QS genes of P.aeruginosa. By PCR technology, the results showed that all isolates were positive for all genes by 6/10 (60%) (pqsA, pqsR1 , lasR) , As for K. pneumoniae, isolates were positive for all genes with a percentage of 9/10 (90 0%) (Luxs, LsrR and LsrK), These findings suggest that PQS can function as an intercellular signal in P. aeruginosa that is not restricted only to alkyl homoserine lactones (AHL) and confirmed the existence of a relationship connection between LuxS-dependent AI-2 signals and biofilm formation in species many bacteria like K.pneumoniae.

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