Invasiveness in chickens, stress resistance and RpoS status of wild-type Salmonella enterica subsp. enterica serovar typhimurium definitive type 104 and serovar enteritidis phage type 4 strains.

The heat and acid resistance and the ability to survive airdrying on commonly used kitchen surfaces were assessed for clinical and environmental strains of Salmonella enterica subsp. enterica serovar Typhimurium, definitive type (DT) 104. Three out of thirty-eight strains of DT 104 were found to be more sensitive in stationary phase to the stresses examined than the other strains.

The biocontrol strain Pseudomonas fluorescens F113 produces the Rhizobium small bacteriocin, N-(3-hydroxy-7-cis-tetradecenoyl)homoserine lactone, via HdtS, a putative novel N-acylhomoserine lactone synthase.

Several different species of Pseudomonas: produce N:-acylhomoserine lactones (AHLs), quorum-sensing signal molecules which are involved in the cell-density-dependent control of secondary metabolite and virulence gene expression. When Pseudomonas fluorescens F113 was cross-streaked against AHL biosensors capable of sensitively detecting either short (C(4)-C(8)) or long (C(10)-C(14)) acyl chain AHLs, no activity was detectable. However, by extracting cell-free stationary-phase culture supernatants with dichloromethane followed by reverse-phase HPLC, three distinct fractions were obtained capable of activating the AHL biosensors.

Cryptic carbapenem antibiotic production genes are widespread in Erwinia carotovora: facile trans activation by the carR transcriptional regulator.

Few strains of Erwinia carotovora subsp. carotovora (Ecc) make carbapenem antibiotics. Strain GS101 makes the basic carbapenem molecule, 1-carbapen-2-em-3-carboxylic acid (Car).

Quorum sensing and Chromobacterium violaceum: exploitation of violacein production and inhibition for the detection of N-acylhomoserine lactones.

Quorum sensing relies upon the interaction of a diffusible signal molecule with a transcriptional activator protein to couple gene expression with cell population density. In Gram-negative bacteria, such signal molecules are usually N-acylhomoserine lactones (AHLs) which differ in the structure of their N-acyl side chains. Chromobacterium violaceum, a Gram-negative bacterium commonly found in soil and water, produces the characteristic purple pigment violacein.