The spatial distribution of copper was determined in Escherichia coli PHL628 biofilms
using a scanning electrochemical microscope consisting of an ultramicroelectrode in
conjunction with a piezoelectric micro-positioning system. Because of their low
concentrations, dissolved copper species in the biofilm were determined using
voltametric stripping at - 0.7 V (vs. Ag/AgCl). As the microelectrode was slowly moved
toward the biofilm, the position of the bulk solution-biofilm interface was identified from
an abrupt change in current produced by 0.4 mM hydroxymethyl ferrocene that was
added as a redox mediator. After a 2 hour exposure to 0.2 mM copper, Cu was located in
the upper region of the biofilm with a penetration depth less than 150 µm. A one-dimensional
diffusive transport model adequately described the spatial distribution of
copper in the biofilm, but the Cu retardation factor in the biofilm was more than 3-fold
larger than that calculated from the isotherm for Cu binding to suspensions of E. coli
PHL628 cells. The electrochemical technique in combination with model calculations
provide direct evidence in support of the concept that retarding metal diffusion could be
an important factor for survival of biofilm microorganisms. Includes 8 references, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 270 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 7 |
| Published : | 06/01/2006 |
