Introduction :

Stenotrophomonas maltophilia is a gram-negative bacterium constitutively occurring in man but has drawn more concern due to its notable adaptability and opportunistic nosocomial infections especially in immunocompromised patients. As an opportunistic pathogen, this organism has the propensity to form biofilms rendering it highly resilient to antibacterial measures and host immune system. Biofilms are three-dimensional structures of multicellular aggregates encased in a self-made matrix of biofilm associated EPS (extracellular polymeric substances) wherein understanding the protein content is imperative in the study of biofilm"s pathobiology.

Objectives:

So far little is known what peptides are secreted by the pathogen S. maltophilia in single and mixed species biofilms and what they paly role in biofilm formation and pathogenicity.

Materials and methods:

This study focuses on the identification of proteins secreted into the biofilm matrix by S. maltophilia in single or mixed species biofilms. Biofilms were grown under static conditions for 48 hours. Biofilm matrix was isolated using the NaCl method as proposed in ref: Pan, Xiangliang, et al. (2010). After a purification step using the C18 spin Columns, a liquid chromatography (LC) mass spectrometry (MS) tandem system was employed for protein identification[IA1] .

Results:

Our results showed that the majority of proteins identified were exported hypothetical protein, secreted proteases, ton B receptors and adhesins. Most of the ton b receptors have been associated with iron acquisition and the some of the identified proteases have been inked to virulence.

Conclusion:

We have successfully established a method for the isolation and identification of peptides from the biofilm matrix of S. maltophilia. Our Proteomics data showed that the majority of identified proteins are extracellular proteases, receptors involved in iron acquisition , adhesins for cell adhesion and exported hypotheitical proteins.

We are currently analyzing the proteomics profile of S. maltophilia planctonic cultures and S. maltophilia in a mixed species biofilm with P. aeruginosa.