The resistance of your bacteria circuit will depend not just on the bacteria, but the medium that the bacteria is occupying.
If the medium has water or some relatively low conductive component then your applied voltage for any given current will be relatively low.
In the reports you have cited, what mechanical arrangement do they use to pass current through the sample?
The electrodes will also have to be inert, as an electric current will cause electrolytic action at the electrodes if the medium type/ electrode material combination is not right.
Any product of electrolysis may cause the same result you are hoping an electric current may cause, as you have cited, the electrodes caused the demised of the bacteria.
I think a long time ago I read that this method was being used in research to kill the AIDs virus.
To answer your question Tom, and I appreciate the input on this topic. I have pulled a quote out of one of the papers I had received upon request from a couple of these researchers inquiring more details about their experiment setup.
Maybe you can understand this better than I can, but I do feel like they are just placing some wires into a medium broth solution (basicly salty water) with bacteria and trying to zap the bugs.
Designed by the Mayo Division of Engineering, the treatment device consisted of an 8-channel computer controlled current generator that delivers 20–2,000μA of DC; alternatively, a Keithley 2400 SourceMeter (Cleveland, OH) was used. Discs containing biofilm were exposed to DC via platinum electrodes (with the exception of initial catalase, SOD, and antioxidant supplementation assays which used stainless steel electrodes) in previously-described polycarbonate test chambers  (Fig 1). Electrodes measured 1.5 mm in diameter and 55 mm in length. To set up each experiment, biofilm-coated discs were removed from the well plates and rinsed by gently dipping in sterile saline to remove planktonic bacteria. The discs were then placed in test chambers in an upright position with electrodes positioned on both sides, 3 mm from the disc . A 1X phosphate flow buffer was prepared with 426 mg Na2HPO4, 205 mg KH2PO4, and 640 mg glucose in one liter of distilled water, adjusted to a pH of 7.4 and filter sterilized. The stock flow buffer was diluted to 3% (30 ml stock buffer + 970 ml sterile water) for each experiment. The 3% phosphate flow buffer was continuously pumped through each test chamber at 3 ml/hour.
This how they have arranged their method of testing the experiment.
Now, to address @Grump_Mike:
That is the nub of your problem. You have to know what sort of control that this so far mythical, power supply needs.
If their is an on / off control then yes an Arduino can turn it on and off in a PWM manner. What you need is a filter on the power supplies’ output to reduce the full on / off waveform to the average voltage.
You don’t control the current with a series resistor, you limit it. If your sample is changing resistance then I can’t see this adding anything to your results, in fact it will make them more complex to interpret.
A pot is not a good thing to use because at the end of the track you have an increasingly small length of track dissipating and increasingly larger amount of power. This leads to the pot burning out. An extra resistor in series with the pot will be needed to prevent this.
When you mention the control my power supply needs, what exactly do you mean by this? If I were to start this experiment from scratch without any prior knowledge of voltage/current levels wouldn’t I need a source of power to begin my experiment? Something I could just start with by saying, “Hey I am going to try to pump 1 A of current into this strand of bacteria and see what happens?”
I am currently trying to recreate as closely as I can using the successful parameters of these experiments to kill my own bugs, and adapt from there.
I think their might be some confusion amongst the researchers as to what kills bacteria or in fact any living thing. Basically it is the current. The voltage is simply a means to push lethal current through the victim.
For example it takes about 30mA to kill a person, you can get that with a 9V battery. However you must have enough voltage to push that current through the victim and that depends on a lot of factors.
Their is a little rhyme hat goes, “it’s the volts that jolts but the mills that kills”. A person can withstand a very high voltage 10kV can hurt but is by no means fatal, this happens in static discharge from a carpet. The resason people are not killed by carpet static is that the impedance of the static source is very high and that limits the current. If you take your 9V battery and open up the chest and apply wires each side of the heart you can kill some one, although the opening up of the chest alone would probably do it.
It could be that your bacteria are dying because the media they are in is heating up with the current and they’re dying of heat, or the current is actually disturbing the functioning of the cells.
What do you want to show with these tests?
You also bring up a good point about the bacteria dying off, because of the media they are in heating up. I still am not understanding why I couldn’t switch a power supply ‘on and off’ of a set voltage across a load to maybe simulate a square wave?
If my understanding of power electronics, or power engineering is incorrect, please feel free to point me in the right direction. I am open to honest opinion and love to learn more from you guys.