The luxS gene is responsible for the synthesis of AI-2 (autoinducer-2), a signaling molecule that participates in quorum sensing regulation in a large number of bacteria. In this work, we investigated which phenotypes are regulated by luxS gene in Serratia proteamaculans 94, psychrotrophic strain isolated from spoiled refrigerated meat. AI-2 was identified in S. proteamaculans 94, and the luxS gene involved in its synthesis was cloned and sequenced. A mutant with the inactivated luxS gene was constructed. Inactivation of the luxS gene was shown to lead to the absence of AI-2 synthesis, chitinolytic activity, swimming motility, suppression of the growth of fungal plant pathogens Rhizoctonia solani and Helminthosporium sativum by volatile compounds emitted by S. proteamaculans 94 strain, and to a decrease of extracellular proteolytic activity. The knockout of the luxS gene did not affect synthesis of N-acyl-homoserine lactones, lipolytic, and hemolytic activities of S. proteamaculans 94.

• MeSH
• bakteriální proteiny genetika   MeSH
• biofilmy růst a vývoj   MeSH
• fenotyp MeSH
• homoserin analogy a deriváty   metabolismus   MeSH
• laktony metabolismus   MeSH
• lyasy štěpící vazby C-S genetika   MeSH
• maso mikrobiologie   MeSH
• mikrobiální interakce MeSH
• quorum sensing genetika   MeSH
• regulace genové exprese u bakterií MeSH
• Serratia genetika   metabolismus   MeSH
• těkavé organické sloučeniny analýza   MeSH
• umlčování genů * MeSH
• Publikační typ
• časopisecké články MeSH

Pseudomonas chlororaphis strain 449 isolated from the rhizosphere of maize suppresses numerous plant pathogens in vitro. The strain produces phenazine antibiotics and synthesizes at least three types of quorum sensing signaling molecules, N-acylhomoserine lactones. Here we have shown that the rhizospheric P. chlororaphis strains 449, well known strain 30-84 as well as two other P. chlororaphis strains exhibit polygalacturonase activity. Using mini-Tn5 transposon mutagenesis, four independent mutants of strain P. chlororaphis 449 with insertion of mini-Tn5 Km2 in gene gacS of two-component GacA-GacS system of global regulation were selected. All these mutant strains were deficient in production of extracellular proteinase(s), phenazines, N-acylhomoserine lactones synthesis, and did not inhibit the growth of G(+) bacteria in comparison with the wild type strain. The P. chlororaphis 449-06 gacS (-) mutant studied in greater detail was deficient in polygalacturonase, pectin methylesterase activities, swarming motility and antifungal activity. It is the first time the involvement of GacA-GacS system in the regulation of enzymes of pectin metabolism, polygalacturonase and pectin methylesterase, was demonstrated in fluorescent pseudomonads.

• MeSH
• antibióza MeSH
• bakteriální proteiny genetika   metabolismus   MeSH
• houby fyziologie   MeSH
• karboxylesterhydrolasy genetika   metabolismus   MeSH
• laktony metabolismus   MeSH
• mutace MeSH
• polygalakturonasa genetika   metabolismus   MeSH
• Pseudomonas enzymologie   fyziologie   genetika   MeSH
• půdní mikrobiologie MeSH
• regulace genové exprese u bakterií MeSH
• transkripční faktory genetika   metabolismus   MeSH
• vývojová regulace genové exprese MeSH