Jon C Rees | PubMed Health

PubMed2005

Simultaneous detection of two bacterial pathogens using bacteriophage amplification coupled with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

The simultaneous analysis of multiple target microorganisms using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) with bacteriophage amplification is discussed. Following infection of target bacteria with specific bacteriophages, proteins contained in the progeny phage are utilized as a secondary biomarker for the target bacterium. Escherichia coli when mixed with MS2 and MPSS-1 phages specific for E. coli and Salmonella spp., respectively, at levels below their corresponding detection limits, produced only the protein (13.7 kDa) characteristic of the MS2. Likewise, Salmonella spp. when mixed with the two phages only produced a protein (13.5 kDa) characteristic of MPSS-1. When the two bacteria and the two phages were mixed together, proteins characteristic of MS2 and MPSS-1 were observed indicating that both bacteriophages had been amplified. Identification of each bacterium was made based on the presence of the secondary bacteriophage biomarkers. No deleterious effects on bacteriophage amplification were observed because of the presence of multiple bacteria or bacteriophages.

Bacteriophages↗

PubMed2002

Rapid analysis of intact phospholipids from whole bacterial cells by matrix-assisted laser desorption/ionization mass spectrometry combined with on-probe sample pretreatment.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS), utilizing an on-probe sample pretreatment, was applied to the rapid and direct detection of intact phospholipids from whole bacterial cells. The sample preparation procedure involved depositing growing bacterial colonies from culture dishes directly onto the MALDI probe followed by treatment of the sample spot with a 3 micro L aliquot of an aqueous 0.05 M solution of sodium iodide prior to the addition of a 2,5-dihydroxybenzoic acid (DHB) matrix solution (ca. 8 mg dissolved in 70% acetonitrile/30% H(2)O containing 0.1% of trifluoroacetic acid). The MALDI spectra obtained from whole bacteria cells showed a series of ions generated from bacterial phospholipids, such as phosphatidylethanol-amines (PEs) and phosphatidylglycerols (PGs), which were clearly observed as well-resolved peaks. The ranges of the observed total carbon numbers in two acyl groups for PEs and PGs (30-36 and 33-36, respectively) were in good agreement with those reported previously. Furthermore, the distinct discrimination of four species of the Enterobacteriaceae family cultured identically was achieved by using principal components analysis (PCA) conducted on the relative peak intensities of phospholipids observed from the MALDI spectra.

Culture Media↗