Chemistry Reference
In-Depth Information
Figure 1. The epifluorescence images of DAPI-CTC stained
E. coli
treated for 2 days with
(b-d) and without (a) sub-MIC Bi-thiols.
EPS Suppression by Bi-thiols
EPS from suspended cultures of single and multispecies were extracted using
commonly accepted protocols (e.g., centrifugation and cation-exchange resin) and
categorized into free and bound EPS [15, 16, 49, 50]. A comprehensive analysis
of free and bound EPSusing colorimetry, spectroscopy, and microscopy
techniques revealed that generally at near-MICs Bi-thiols could substantially
diminish the EPS production from cells while having a negligible effect on their
growth. Atomic force microscopy images of
E. coli
cultures treated with and
without Bi-thiols (BisBAL, BisEDT or BisPYR) from day 1 and day 2 samples
are shown in Figure 2. These images show that following the treatment with Bi-
thiols the cells were still intact with lower EPS content (Fig.2c-h) when compared
with controls (Fig. 2a-b).
Interestingly, the MICs for cationic BisBAL were similar for all Gram
negative bacteria investigated. As an example, epifluorescence images in Figure
1a-d shows that the viability of
E. coli
was unaffected even after exposure to sub-
MIC BisBAL, BisEDT, and BisPYR for 2 days (and very similar results were
obtained for 5-day exposure) [50].
