The reaction cell was constructed from a glass tube with a Teflon
cover lid which held two identical electrodes. To eliminate crosscontamination,
the reaction cell and electrodes were washed and
rinsed with distilled water and sterilized at 121 ◦C for 15 min before
each incubation and prior to immersion in any of the solution samples.
The commercial sterilized milk was added into the Malthus
glass tubes up to the level of the electrodes.