Lockheed Service News Vol 2 No 2 page 10 had an article on "microbial growth", and Vol 10 No 3 page 8 had a large article on "Chemical Control of Fuel Tank Infestation" which covers the matter at great length, but regarding FSII this bit is relevant ..
"Added to turbine fuel, MIL-I-27686 does indeed reduce the hazards of icing in aircraft fuel systems. But it can do other useful things as well. MIL-I-27686 acts to depress the flash points of such volatile fuels as JP-4, and it also kills the microorganisms that can cause corrosion of aircraft structure and blockage of fuel systems."
The other part relevant to our Herks was the addition of "Strontium Chromate" cartridges to the fuel tanks to also kill off the bugs ..
