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
• Bacterial Proteins genetics   MeSH
• Biofilms growth & development   MeSH
• Phenotype MeSH
• Homoserine analogs & derivatives   metabolism   MeSH
• Lactones metabolism   MeSH
• Carbon-Sulfur Lyases genetics   MeSH
• Meat microbiology   MeSH
• Microbial Interactions MeSH
• Quorum Sensing genetics   MeSH
• Gene Expression Regulation, Bacterial MeSH
• Serratia genetics   metabolism   MeSH
• Volatile Organic Compounds analysis   MeSH
• Gene Silencing * MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Bacterial Proteins MeSH
• Homoserine MeSH
• Lactones MeSH
• LuxS protein, Bacteria MeSH Browser
• Carbon-Sulfur Lyases MeSH
• N-octanoylhomoserine lactone MeSH Browser
• Volatile Organic Compounds MeSH

Resistance to 17 antimicrobials, surface hydrophobicity, motility, biofilm, production of N-acylhomoserine lactone signal molecules (N-butyrylhomoserine lactone and N-3-oxolauroylhomoserine lactone) and response to oxidative stress were analyzed in 47 clinical Pseudomonas aeruginosa strains. In addition to natural resistance, the strains demonstrated the greatest level of resistance to cefotaxime (91.5%). Isolates in the range of 44.7-57.4% were resistant to aminoglycosides and ciprofloxacin, of 25.5-36.2% to cephalosporins. On the other hand, 97.9% remained susceptible to meropenem, 93.6% to piperacillin + tazobactam and 87.2% to piperacillin. The majority of the strains (72.3%) manifested their hydrophilic character. Higher zones of motility showed 12 isolates (in average 54.8 mm) as compared to the others (30.2 mm). Approximately 1/3 of the strains (29.8%) produced a higher amount of biofilm quantified by measuring the absorbance of solubilized crystal violet (0.20-0.46) than the rest of isolates (0-0.19). All but two strains produced N-3-oxolauroylhomoserine lactone and in 48.9% of samples N-butyrylhomoserine lactone were detected. Only four isolates with higher biofilm production showed both types of homoserine lactone. Majority of the strains (70.2%) manifested higher resistance to H2O2 than the rest of the strains. The group of strains resistant to aminoglycosides and ciprofloxacin revealed a significantly higher number of hydrophobic strains (compared with the sensitive ones). In contrast, higher number of strains sensitive to aminoglycosides and ciprofloxacin or only to ciprofloxacin produced N-butyrylhomoserine lactone and biofilm (compared to the resistant ones). Such association was not found among the rest of the tested parameters. The results indicate that the resistance to antimicrobials in P. aeruginosa isolates was not generally associated with changes in the production of the pathogenicity factors.

• MeSH
• Anti-Bacterial Agents pharmacology   MeSH
• Drug Resistance, Bacterial * MeSH
• Biofilms growth & development   MeSH
• Phenotype MeSH
• Adaptation, Physiological MeSH
• 4-Butyrolactone analogs & derivatives   biosynthesis   MeSH
• Gentian Violet metabolism   MeSH
• Hydrophobic and Hydrophilic Interactions MeSH
• Humans MeSH
• Oxidative Stress MeSH
• Oxidants pharmacology   MeSH
• Hydrogen Peroxide pharmacology   MeSH
• Movement MeSH
• Pseudomonas Infections microbiology   MeSH
• Pseudomonas aeruginosa drug effects   isolation & purification   pathogenicity   MeSH
• Virulence MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Anti-Bacterial Agents MeSH
• 4-Butyrolactone MeSH
• Gentian Violet MeSH
• Oxidants MeSH
• Hydrogen Peroxide MeSH

Serotyping and some potential virulence-associated markers were investigated in Plesiomonas shigelloides strains isolated from humans, animals and aquatic environments. Surface properties of these strains were evaluated using Congo red binding, salt-aggregation test, bacterial adherence to xylene and motility. Production of pancreatic elastase, proteinase (consistent with subtilisin Carlsberg), triacylglycerol lipase, histidine decarboxylase and beta-hemolysin was also determined. In addition, detection of signal molecules such as C4-C8 unsubstituted N-acylhomoserine lactones (AHLs) was performed. The serological typing of the P. shigelloides strains showed that the isolates belonged to 13 different serovars. The majority of the strains were hydrophobic and motile. The strains produced low levels of elastase, proteinase and histidine decarboxylase whereas triacylglycerol lipase activity was relatively high. Only 23.3 % of the strains produced hemolysin. The AHLs signal molecules were not detected. P. shigelloides strains were able to produce a variety of potential virulence markers which may be involved in the pathogenesis of Plesiomonas-associated infections.

• MeSH
• Bacterial Adhesion MeSH
• Species Specificity MeSH
• 4-Butyrolactone analogs & derivatives   metabolism   MeSH
• Gram-Negative Bacterial Infections microbiology   MeSH
• Hemolysin Proteins biosynthesis   MeSH
• Histidine Decarboxylase biosynthesis   MeSH
• Humans MeSH
• Lipase biosynthesis   MeSH
• Water Microbiology MeSH
• Pancreatic Elastase biosynthesis   MeSH
• Plesiomonas classification   isolation & purification   metabolism   pathogenicity   MeSH
• Serotyping MeSH
• Virulence MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• 4-Butyrolactone MeSH
• Hemolysin Proteins MeSH
• Histidine Decarboxylase MeSH
• homoserine lactone MeSH Browser
• Lipase MeSH
• Pancreatic Elastase MeSH

Quorum-sensing control mediated by N-acylhomoserine lactone (AHL) signal molecules has been established as a key feature in the regulation of various metabolic traits in many bacteria. Approximately 300 strains representing 6 genera and 18 species of soil-borne and plant-associated Gram-negative bacteria isolated in various regions of the former USSR using two reporter systems were screened for AHL production. The production was observed in 17.5% of the screened bacterial strains. Positive response was detected in all of the 14 tested strains of Erwinia herbicola, in 41 of the 239 strains of Pseudomonas species; in all 5 strains of Xanthomonas ampelina, X. campestris pv. malvacearum, pv. translucens, pv. vesicatoria and in one strain of Pantoea stewartii. AHL assay of 41 strains of X. maltophilia (syn. Stenotrophomonas maltophilia) isolated from soils with Chromobacterium violaceum reporter has revealed no strains synthesizing these signal molecules; 26 strains analyzed with Agrobacterium tumefaciens reporter showed the same result.

• MeSH
• 4-Butyrolactone analogs & derivatives   biosynthesis   metabolism   MeSH
• Gram-Negative Bacteria growth & development   metabolism   MeSH
• Soil Microbiology * MeSH
• Plants microbiology   MeSH
• Signal Transduction physiology   MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• 4-Butyrolactone MeSH
• homoserine lactone MeSH Browser