Role of the Stationary Growth Phase Sigma Factor RpoS of Burkholderia pseudomallei in Response to Physiological Stress Conditions

The Burkholderia pseudomallei rpoS gene was identified, and an rpoS null mutant was constructed. The mutant was shown to have an increased sensitivity to carbon starvation and oxidative stress. By using rpoS-lacZ fusions, transcription of rpoS was shown to be growth phase regulated, reaching a peak upon entry into stationary phase

Functional Genetic Analysis Reveals a 2-Alkyl-4-Quinolone Signaling System in the Human Pathogen Burkholderia pseudomallei and Related Bacteria.

Pseudomonas aeruginosa synthesizes diverse 2-alkyl-4(1H)-quinolones (AHQs), including the signaling molecule 2-heptyl-3-hydroxy-4(1H)-quinolone (PQS), via the pqsABCDE locus. By examining the genome databases, homologs of the pqs genes were identified in other bacteria. However, apart from P. aeruginosa, only Burkholderia pseudomallei and B. thailandensis contained a complete pqsA–E operon (termed hhqA–E). By introducing the B. pseudomallei hhqA and hhqE genes into P. aeruginosa pqsA and pqsE mutants, we show that they are functionally conserved and restore virulence factor and PQS production. B. pseudomallei, B. thailandensis, B. cenocepacia, and P. putida each produced 2-heptyl-4(1H)-quinolone (HHQ), but not PQS. Mutation of hhqA in B. pseudomallei resulted in the loss of AHQ production, altered colony morphology, and enhanced elastase production, which was reduced to parental levels by exogenous HHQ. These data reveal a role for AHQs in bacterial cell-to-cell communication beyond that seen in P. aeruginosa

ABO Blood-Typing Using an Antibody Array Technique Based on Surface Plasmon Resonance Imaging

In this study, readily available antibodies that are used in standard agglutination tests were evaluated for their use in ABO blood typing by a surface plasmon resonance imaging (SPR imaging) technique. Five groups of antibodies, including mixed clones of anti-A, anti-B, and anti-AB, and single clones of anti-A and anti-B, were used to construct the five-line detection arrays using a multichannel flow cell in the SPR imager. The red blood cell (RBC) samples were applied to a multichannel flow cell that was orthogonal to the detection line arrays for blood group typing. We found that the blood samples were correctly grouped in less than 12 min by the SPR imaging technique, and the results were consistent with those of the standard agglutination technique for all 60 samples. We found that mixed clones of antibodies provided 33%–68% greater change in the SPR signal than the single-clone antibodies. Applying the SPR imaging technique using readily available antibodies may reduce the costs of the antibodies, shorten the measurement time, and increase the throughput