Agriculture Reference
In-Depth Information
Electrophoresis works in a similar manner and transports negatively charged cells toward
the system's anode(-). As such, movement is determined by the electrical charge
characteristics of the particular bacterial strain. Thus, the direction of bacterial movement
can be controlled by altering the electrical field and its polarity.
In electrical experiments performed by Suni et al. 1 , bacterial strains were found to disperse
faster when they move via electroosmotic water flows toward the cathode. When
comparing migration rates across different soil types, it turns out that bacteria:
• Flows fastest within fine sands (1.0 cm/h)
• Flows at mid-speed in garden soils (0.6cm/h)
• Flows slowest in clays (0.1cm/h)
Changes in Metabolic Activity
Inadditiontobeingusedformovingmicrobesaroundaliquidmedium,electric fieldshave
also been found to alter cellular metabolism.
While a significant body of research covers the study of electric fields on microbes, the
effects of electrical stimulation can vary significantly between helpful and harmful. This
depends upon the type of bacteria involved and the nature of the electrical stimuli. For
example, in a study of alternating current (AC) electric fields on Lactobacillus acidophilus
during fermentation, a frequency of 60Hz with high-frequency harmonics present was
found to cause a significant increase in bacterial growth 2 . On the other hand, in a similar
study on AC fields, when the applied voltage is at a much higher level (approximately
6kV or 6000 volts), the result was a decrease in the bacterial population 3 . This realization
has become key in the deliberate sterilization of different forms of bacteria for use in food
processing and other industries 4 .
On a more positive front, a study from the Chinese Journal of Applied Chemistry showed
that the metabolic activity of Bacillus subtilis in a low-voltage DC field was multiplied
between 1.9 and 3.8 times over the control when exposed to extremely low amounts of
current (on the order of 45 microamps or so) 5 .
What are the mechanisms behind these effects?
While certainly more that could be learned, the mechanisms that cause these effects are
likely due to a good number of the following:
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