Math puzzle

[ProfessorGAC]

10. Safe To Kill All Microbes At Once

I worked with several microbiologists. Mostly because for a while I was doing work optimizing conditions to improve purity & quality of the active ingredients in sanitizing cleaners.
Also, several high end surfactant products are so biodegradable, they are susceptible to microbial contamination. So, methods to sanitize and create engineering barriers to entry were done commonly and the micro folks had to challenge test the effectiveness.
I saw lots of tests run for microbial content & challenge testing for antimicrobial agents.
Otherwise I wouldn't know the details I know.