Citation:

DONOHUE, M. J., W. SMALLWOOD, J. BEST, J. A. SHOEMAKER, AND M. R. RODGERS. THE USE OF MATRIX-ASSISTED LASER DESORPTION/IONIZATION-MASS SPECTROMETRY FOR THE IDENTIFICATION OF AEROMONAS ISOLATES OBTAINED FROM WATER DISTRIBUTION SYSTEMS. Presented at 8th International Symposium on Aeromonas and Plesiomonas, Halifax, NS, CANADA, June 15 - 18, 2005.

Impact/Purpose:

This particular task is comprised of 4 subtasks: 1.) Characterization of Potential Viral Biomarkers by Mass Spectrometry; 2.) Characterization of Parasites by Mass Spectrometric Techniques;

3.) Rapid Discrimination of Bacterial Indicators of Fecal Contamination and Bacterial Pathogens by Mass Spectrometric Techniques; and 4.) Investigation of Aeromonas Virulence Factors Using Mass Spectrometry.

The purpose of this research project is to use mass spectrometric techniques, such as electrospray ionization (ESI), capillary electrophoresis (CE) and matrix assisted laser desorption ionization (MALDI) mass spectrometry, to provide "protein mass fingerprinting" and protein sequencing information for viruses, bacteria and protozoa that cause waterborne disease. These protein mass fingerprinting libraries will be evaluated to determine whether mass spectrometric techniques can identify protein fingerprints related to the infectivity/viability of selected microorganisms and whether they can differentiate between infective / non-infective genus and strains of the selected microorganisms. The characteristic proteins identified by mass spectrometry as markers of infectivity/viability or strain differentiation can then be used to develop more sensitive microbiological drinking water methods.

Description:

Matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS) has long been established as a tool by which microorganisms can be characterized and identified. EPA is investigating the potential of using this technology as a way to rapidly identify Aeromonas species found in drinking water. A number of bacteria, including Aeromonas hydrophila, are listed on the Agency's 1998 Contaminant Candidate List (CCL) as research needs. The genus Aeromonas is one of several medically significant genera that have gained prominence due to their evolving taxonomy and controversial role in human diseases. In this study, MALDI-MS was used to develop a library of proteomic signatures for seventeen species of Aeromonas. These seventeen species were represented by thirty-two strains, which included type, reference and clinical isolates. This library was then used to rapidly identify strains of Aeromonas obtained during two surveys conducted by EPA during 2000 and 2001. In these two blind studies, forty survey strains, previously assigned to a species based on biochemical test results, were analyzed by MALDI-MS. The proteomic signatures of the survey strains were then compared against the library of "known" proteomic signatures to determine the identity of the Aeromonas isolates. In the first blind study, the identification by the MALDI-MS analysis correlated 100% with the biochemical identification. In the second blind study, eighteen of the twenty strains analyzed by MALDI-MS correlated with the biochemical identification. These data demonstrate that MALDI-MS analysis can rapidly and accurately identify species of the genus Aeromonas, making it a powerful tool especially suited for environmental monitoring and detection of biological hazards.

Record Details: