Glycoprotein and Protein Markers for Strain Differentiation and Growth Environment or Media Attribution

Recent experience has demonstrated that protein markers can provide potentially vital identifying and bioforensic information. The masses of constitutively expressed proteins and their peptide fragments can be used to identify bacterial isolates. Protein marker mass variation reflects the underlying amino acid sequence variation to provide information complementary to genetic sequence analysis. Protein markers (identified by mass or sequence) that are conserved or variable can be readily detected. Examples of constitutively expressed proteins that have been extensively characterized include the exosporium BclA and BclB proteins and small acid-soluble proteins (SASPs). Finally, gene expression (usually assessed at the mRNA level) can vary in response to different environmental conditions. As a result, the profile of protein markers of the organism also reflects the culture environment. Mass spectrometric tools can be used to access the same information on culture-related protein expression variation. However, unlike genetic methods, with proteomic methodology, there is the potential to differentiate samples prepared in distinct growth environments. This potential could provide additional clues for investigative leads or forensic attribution.