Article Figures & Data
Figures
- FIG. 1.
Photomicrographs illustrating the development of B. cereus DL5 biofilms on glass wool in SONLB at 2 h (a), 18 h (b and c), and 42 h (d) after inoculation.
- FIG. 2.
Culturable counts (expressed as log10 CFU per milliliter of culture) (a) and cell volumes (expressed as cubic micrometers) (b) of B. cereus DL5 planktonic cells (P), PGW cells (SIP), and biofilm cells (A) grown for 2 and 18 h in SONLB at 37°C. Different letters indicate that differences are statistically significant (P < 0.05).
- FIG. 3.
Extracellular protein profiles of 18-h-old planktonic cells grown in the absence of glass wool (a) and combined PGW-biofilm cells (b) of B. cereus DL5 following separation by one-dimensional SDS-12% PAGE and silver staining. A BENCHMARK prestained protein ladder (GIBCO BRL) was used as the molecular weight (MW) marker (lane M). Unique bands are indicated by arrows.
- FIG. 4.
2DE proteome patterns for 2-h-old B. cereus DL5 planktonic cells (a), PGW cells (b), and biofilm cells (c) and 18-h-old B. cereus DL5 planktonic cells (d), PGW cells (e), and biofilm cells (f). Unique protein spots are indicated by arrows. The horizontal axes represent pIs of the isoelectric focusing gradients, and the vertical axes represent molecular masses (MW), based on comigration of Bio-Rad 2-D SDS-PAGE standards (Roche Diagnostics GmbH).
Tables
- TABLE 1.
Protein expression in B. cereus DL5 planktonic, PGW, and biofilm cells following 2 and 18 h of culturing in the absence and presence of glass wool
Protein expression No. of spots % of total spots (n = 345) Proteins unique to a specific growth phase Planktonic cells (2 h) 1 0.3 PGW cells (2 h) 2 0.6 Biofilm cells (2 h) 15 4.4 Planktonic cells (18 h) 1 0.3 PGW cells (18 h) 7 2.3 Biofilm cells (18 h) 7 2.0 Proteins up-regulated in a specific phase compared with the levels of the corresponding spot in other phases Planktonic cells (2 h) 3 0.9 PGW cells (2 h) 10 2.9 Biofilm cells (2 h) 4 1.2 Planktonic cells (18 h) 7 2.0 PGW cells (18 h) 30 8.7 Biofilm cells (18 h) 19 5.5 Proteins present in a specific phase regardless of time (2 h or 18 h) Planktonic cells 0 0 PGW cells 1 0.3 Biofilm cells 5 1.5 Proteins present in all phases and always at the same level (no up- or down-regulation) 35 10.1 Proteins present in planktonic and PGW cells and absent in biofilm cells 11 3.2 Proteins present in PGW and biofilm cells and absent in planktonic cells 0 0 Proteins present in planktonic and biofilm cells and absent in PGW cells 0 0 After 2 h present only in biofilm cells; after 18 h present in PGW and biofilm cells 2 0.6 After 2 h present only in planktonic cells; after 18 h present in planktonic and PGW cells 1 0.4 - TABLE 2.
Growth phase-related differences in the levels of expression of proteins selected for N-terminal protein sequencing
Protein spot Level of expression Planktonic cells (2 h) PGW cells (2 h) Biofilm cells (2 h) Planktonic cells (18 h) PGW cells (18 h) Biofilm cells (18 h) B5a 0a 0 0 −2 −1 −1 B11b 0 1 2 0 2 0 D5h 0 0 0 −1 3 3 E1d 0 0 0 0 1 1 E7g Ab A 0 A 0 0 E7h 0 0 3 0 3 3 E9p A A A A A Uc G1b 0 1 2 2 3 3 ↵a A value of 0 indicates a level of synthesis similar to that of the corresponding spot in the 2-h planktonic growth phase (reference spot intensity). A positive value indicates up-regulation, and a negative value indicates repression or down-regulation.
↵b A, protein spot is absent.
↵c U, protein spot is unique to the growth phase.
- TABLE 3.
Summary of the proteins identified from 2DE gels of B. cereus DL5 whole-cell protein extracts
Protein spot Protein identity Function N-terminal sequence Estimated from gel Calculated from sequence Accession no. Size (kDa) pI Size (kDa) pI B. cereus databasea SWISS-PROT protein database B5a Pyruvate dehydrogenase E1 component, beta subunit (PdbB) Pyruvate + lipoamide → S-acetyl-dihydro-lipoamide + CO2 QMTMIQAITD 36 4.90 35.23 4.75 RZC01921 P21882 B11b Unknown MNVKRHM 82 4.80 D5h l-Lactate dehydrogenase (LctE) Pyruvate + NADH → l-lactate + NAD+ MKKGINRVVL 34 5.50 34.79 4.99 RZC05932 P13714 E1d Hypothetical cytosolic protein Unknown AKDFYSAIEDRRS 24 5.65 23.07 5.21 RZC03248 A83323 E7g cOTCase l-Citrulline + Pi → carbamoyl phosphate + ornithine MLMTRPNLKGRS 39 5.70 37.46 5.35 RZC04697 O86132 E7h cOTCase l-Citrulline + Pi → carbamoyl phosphate + ornithine MLMTRPNLKGRS 39 5.80 37.46 5.35 RZC04697 O86132 E9p Unknown MPPVVI 54 6.10 G1b YhbH light-repressed protein A Unknown MKFNI 23 6.20 21.08 5.63 RZC04452 P28368 ↵a Accession number obtained from the B. cereus database website (http://wit.Integratedgenomics.com/Public/IG_Release.html).
b Accession number obtained from the SWISS-PROT protein database website (http://www.expasy.ch/sprot/).
