Do the math(s)
500 milliAmps. The team estimate that each bacteria cell can give off about 100,000 electrons per second.
[...] In the electrochemical chamber there are approximately 100 billion bacterial cells,
10^5 x 10^11 = 10^16 electrons per second
1A =~ 6 x 10^18 electrons per second -> 0.5A =~ 3 x 10^18 electrons per second
Two orders of magnitude error. Tsk