You are here:
FINGERPRINTING OF FECAL ENTEROCOCCI BY MATRIX ASSISTED LASER DESORPTION IONIZATION MASS SPECTROMETRY
Citation:
Glassmeyer, S, C A. Kelty, AND J Santo Domingo. FINGERPRINTING OF FECAL ENTEROCOCCI BY MATRIX ASSISTED LASER DESORPTION IONIZATION MASS SPECTROMETRY. Presented at American Society of Microbiology, Washington, DC, May 18-22, 2003.
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:
The fecal enterococci group has been suggested as an indicator of fecal contamination in freshwater and marine water systems and as a potential target for bacterial source tracking of fecal pollution. While many studies have described the diversity of enterococci in environmental waters, most of these studies have relied on biochemical characteristics that can not discriminate between some of the different species of fecal enterococci. In this study, we evaluated the use of whole cell protein profiles using matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) as a tool to identify different enterococci species. Seven enterococci species were used in this study, namely, Enterococcus faecalis, E. faecium, E. durans, E. gallinarum, E. avium, E. mundtii, and E. casseliflavus. Analysis of protein spectral profiles of masses lower than 2000 mass-to-charge (m/z) were identical between all enterococci species tested suggesting that these might be characteristic of the enterococci group. While many peaks were also shared among the different enterococci species in the 4,000 to 11,000 m/z range, each species showed distinctive peaks, primarily in the 6,000 to 7,000 m/z region. When environmental isolates were tested, the signature peaks were observed in many of the different isolates, suggesting that these peaks could be used for species identification. Sequence analysis of the environmental isolates 16S rDNA confirmed the identity of the strains tested. The results from this study indicate that the analysis of whole cell by MALDI generates a protein profile which can be used for the rapid identification of fecal enterococci environmental isolates. Since not all environmental isolates that belong to the same species had an identical protein profile, these results suggest that MALDI may also be used to discriminate between different strains of the same enterococci species.