title: Comparative proteomic analysis of planktonic and immobilized Pseudomonas aeruginosa cells: a multivariate statistical approach.
abstract: The protein maps of Pseudomonas aeruginosa cells from two natural (attached) and one artificial (gel-entrapped) immobilized-cell (IC) systems, together with their free (suspended) counterparts, were compared after incubation for 18 or 48 h in a minimal salt medium. Principal component analysis (PCA) was used to interpret the variations in protein spot densities that were observed on electropherogram obtained by two-dimensional electrophoresis (2-DE). PCA of the 2-DE data, a matrix of 933 rows (observations, i.e., spot density values) and 12 columns (variables, i.e., incubation conditions), in which observations were standardized horizontally, extracted four principal components (PCs) accounting for 78.75% of the variability in the protein expression profiles. PC1 opposed the two modes of growth (planktonic and immobilized) while PC2 discriminated between the incubation times of free cell cultures. The incubation conditions of ICs, including the immobilization procedure (entrapment vs attachment) and the nature of the biofilm substratum, were fairly separated in PC3xPC4. The dependence of the protein patterns on the cell immobilization process was further illustrated by the identification of a number of peptides whose amount remained unchanged or was altered in ICs compared to free bacteria. These results reinforce the topical assertion that bacteria in the immobilized state display a specific physiological behavior but also question the existence of a unique IC phenotype.
authors.affiliation: Bacteria Immobilization, Biofilms and Resistance Group, UMR 6522 CNRS, University of Rouen, Mont-Saint-Aignan, France.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Vilain
authors.forename: Pascal
authors.initials: P
authors.lastname: Cosette
authors.forename: Marie
authors.initials: M
authors.lastname: Hubert
authors.forename: Catherine
authors.initials: C
authors.lastname: Lange
authors.forename: Guy-Alain
authors.initials: GA
authors.lastname: Junter
authors.forename: Thierry
authors.initials: T
authors.lastname: Jouenne
mesh_terms: D001426:Bacterial Proteins / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D018441:Biofilms; D002478:Cells, Cultured; D015180:Electrophoresis, Gel, Two-Dimensional; D010933:Plankton / Q000737:chemistry* / Q000378:metabolism; D020543:Proteome / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D040901:Proteomics; D011550:Pseudomonas aeruginosa / Q000737:chemistry* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D020543:Proteome