Article Figures & Data
Figures
- FIG. 1.
Effect of NAC on bacteria cultured in 20% LB. Bacterial growth, expressed as optical density at 600 nm [OD(600nm)], was measured for 24 h. Symbols: •, no NAC;, ×, 0.25 mg of NAC ml−1; □, 0.5 mg of NAC ml−1; ▪, 1.0 mg of NAC ml−1; ○, 2.0 mg of NAC ml−1. The growth of A. lwoffii (a), A. baumannii (b), E. cloacae (c), K. pneumoniae (d), P. mendocina (e), a multispecies community consisting of A. baumannii, P. mendocina, K. pneumoniae, A. lwoffii, E. cloacae,S. warneri, and Bacillus sp. (f), Bacillus sp. (g), B. cereus (h), B. megaterium (i), B. subtilis (j), and S. warneri (k) was examined. The error bars indicate the standard deviations of the means for three experiments.
- FIG. 2.
Effect of NAC on EPS production. Bacteria were grown in 20% LB overnight in the presence or absence of NAC and then starved in PS for 48 h. Open columns, no NAC; cross-hatched columns, 0.25 mg of NAC ml−1; grey columns, 0.5 mg of NAC ml−1. The bars indicate the standard deviations of the means for four experiments. Abbreviations: K.p, K. pneumoniae; A.b, A. baumannii; B.m, B. megaterium; B.s, B. subtilis; B.c, B. cereus; A.l, A. lwoffii; P.m, P. mendocina; E.c, E. cloacae; S.w, S. warneri; B, Bacillus sp. NM, not measured.
- FIG. 3.
Effect of NAC on EPS production by starving bacteria. Bacteria were grown in 20% LB overnight in the absence of NAC, washed, and subsequently exposed to 0.5 mg of NAC ml−1 in PS for 48 h. Open columns, no NAC; cross-hatched columns, 0.5 mg of NAC ml−1. The bars indicate the standard deviations of the means for three experiments. Abbreviations: B.c, B. cereus; A.l, A. lwoffii; P.m, P. mendocina; S.w, S. warneri; B, Bacillus sp.
- FIG. 4.
Effect of NAC on degradation of EPS. Isolated EPS from K. pneumoniae, B. megaterium, B. subtilis, B. cereus, E. cloacae, and P. mendocina, as well as dextran, were incubated in the presence or absence of 0.5 mg of NAC ml−1 for 1 h at room temperature. Open columns, no NAC; cross-hatched columns, 0.5 mg of NAC ml−1. The bars indicate the standard deviations of the means for three experiments. The values for dextran (0.5 mg ml−1) were not affected by NAC (the values were too small to show). Abbreviations: K.p, K. pneumoniae; B.m, B. megaterium; B.s, B. subtilis; B.c, B. cereus; E.c, E. cloacae; P.m, P. mendocina.
- FIG. 5.
Numbers of cells that adhered to stainless steel surfaces after 24, 48, and 72 h of incubation in 20% LB. The seven-member multispecies community comprised A. baumannii, A. lwoffii, Bacillus sp., E. cloacae, K. pneumoniae, P. mendocina, and S. warneri. Open columns, no NAC; cross-hatched columns, 0.5 mg of NAC ml−1. The bars indicate the standard deviations of the means for three experiments. Abbreviations: K.p, K. pneumoniae; E.c, E. cloacae; mix, multispecies community.
- FIG. 6.
Numbers of cells that adhered to stainless steel surfaces after 24, 48, and 72 h of incubation in process water. The seven-member multispecies community comprised A. baumannii, A. lwoffii, Bacillus sp., E. cloacae, K. pneumoniae, P. mendocina, and S. warneri. Open columns, no NAC; cross-hatched columns, 0.5 mg of NAC ml−1. The bars indicate the standard deviations of the means for three experiments.
- FIG. 7.
Acridine orange-stained K. pneumoniae attached to stainless steel surfaces after 72 h of incubation in 20% LB. (a) No NAC in the medium; (b) 0.5 mg of NAC ml−1 in the medium.
- FIG. 8.
Attachment of K. pneumoniae to stainless steel surfaces after 72 h of incubation in 20% LB in the absence of NAC (a) and in the presence of 0.5 mg of NAC ml−1 (b). WGA lectin labeled with the fluorescent probe tetramethyl rhodamine isocyanate was used to visualize CPS and EPS.
Tables
- TABLE 1.
Bacterial strains used in this study
Taxon Isolation source CCUG ref- erence no. Reference or source Gram-negative bacteria Acinetobacter baumannii Biofilm in white water 39226 This study Acinetobacter lwoffii Biofilm in wire water 39223 This study Enterobacter cloacae Biofilm in wire water 39230 This study Klebsiella pneumoniae Biofilm in white water 39227 This study Pseudomonas mendocina Biofilm in white water 39225 This study Gram-positive bacteria Bacillus sp. Biofilm in white water 39224 This study Bacillus cereus 6514 CCUG Bacillus megaterium 1817 CCUG Bacillus subtilis 1638 CCUG Staphylococcus warneri Biofilm in white water 39229 This study
