Biostatic mechanisms

With some biocide treatments there is a simple direct relationship between ATP and viable cell counts. However, where the mechanism of biocide action is related to influences on cell bioenergetics, or the concentration range employed is biostatic and affects cell metabolism, then ATP results may not follow the same pattern as microbial counts. Under these circumstances low ATP results at relatively high microbial levels might be expected but it is also possible that ATP levels increase over a period of time. 

Additives that control bacterial growth may therefore exert both biostatic and biocidal effects. The mechanism of action responsible for each effect is not generally the same. Biostatic action is considered to represent metabolic inhibition which is released when the additive is removed. Biocidal activity causes irreversible damage to a vital structure or function of the cell. Dispersants may also be used to prevent attachment to a surface. 

---