Stenotrophomonas maltophilia are ubiquitous environmental bacteria that recently have received much attention as emerging pathogen causing respiratory and nosocomial infections in patients1. S. maltophilia forms structured communities called biofilms on abiotic surfaces as well as epithelial cells. Bacterial biofilms, namely cells embedded in the extracellular matrix composed of polysaccharides (exopolysaccharides, EPS), proteins, and nucleic acids, have been found to protect the microbial community from environmental stresses2. Lipopolysaccharide (LPS), consisting of variable O-antigen, more conserved core and lipid A regions, represents the major component of the cell envelope of Gram-negative bacteria. Changes in LPS expression have been correlated with structural changes in bacterial biofilm3,4. Additionally, it was reported that the expression of EPS actively promotes biofilm formation2.
In order to understand the role of cellular and extracellular components of S. maltophilia in the formation of biofilm, bacteria were grown either in T125 tissue culture flasks (adherence to plastic) or on lung epithelial cells, where they separated into populations, which grew either adherent to cells or plastic or maintaining a planktonic life style. Proteomics of these distinct populations revealed differential protein expression profiles of biofilm vs. planktonic ones with proteins involved in LPS synthesis (category "cell wall/membrane biogenesis") upregulated in the biofilm populations.
Preliminary chemical studies, at first focused on LPS, showed differences in the LPS profiles as well as sugar composition of the LPS core region in biofilm vs. planktonic bacteria. The more detailed structural work utilizing NMR spectroscopy of LPS as well as EPS will be discussed.
References:
1. Brook J.S. 2012.Clin Microbiol Rev.2-41
2. Irie Y. et al. 2012. PNAS 109: 20632–20636
3. Lee Y.W et al. 2010. Lett Appl Microbiol 50: 452–456
4.
Lau P.C et al. 2009. J Bacteriol 191: 6618–6631
