As stated before, Prist is a glycol based liquid that works magic preventing water dissolved in fuel to freeze up in ice crystals and block filters. IMO Not much different than wing anti-ice. Prist does not advertise themselves as a anti-fungal/anti-microbial additive. Bio-Bor is the product used to kill living things inside fuel tanks.
Old generation citation I and II's to needed Prist as a regular basis to avoid this same problem, and some pilots i know still use it in Beechjets, i think they do not have fuel heaters.
Just as a note, The citation Bravo, due to a good Oil to Fuel heat exchanger do not need that stuff, but not long ago i had a "FUEL GAUGE" light in the master warning panel, indicating an error on the fuel gauging system, possibly caused by long term fuel contamination. the option to fix it was defueling the airplane, opening the wet wing and change on one the offending capacitor probes (read expensive). An old mechanic told me to try first putting pre-mixed Prist in Jet-A at any airport that offers it and monitor... You know what? the fuel gauge problem went away in just five flights and has not recurred agin in two years, so I found another use to Prist.
Regarding the toxicity and cancer potential, I think is no worse that some airport food I've had to eat in some long days...