A RAPID, INEXPENSIVE AND QUALITATIVE PROTOCOL FOR DETERMINING MICROBIAL GROWTH INHIBITION IS DETAILED
BY RESEARCHERS FROM METHOD PRODUCTS AND THE US DEPARTMENT OF AGRICULTURE.
TO LEARN MORE ABOUT THE STUDY PROTOCOL, SEE P. 44.
OVER BILLIONS of years, organisms have evolved chemical defenses to combat pathogenic microbial growth. With a parallel goal in mind, home and personal care products
are formulated with chemical preservatives that prevent contamination by microbes.1,2 Unfortunately, many conventional, broad-spectrum preservatives have been associated with adverse human
and environmental health outcomes and negative consumer
perception.2 These concerns have led to interest in developing
a broader collection of safe and effective chemical preservatives
that are inspired by, or derived from, natural sources.
Despite this interest, safer natural preservatives are often
less effective than conventional ones. While preservation can be
easily achieved at acidic (e.g., pH < 4) and basic (e.g., pH > 10)
ranges, many preservatives do not function optimally at neutral
pH ranges, the latter of which are more likely to allow the growth
of pathogenic bacteria. Preservatives may also be deactivated by
other components (e.g. emulsifiers) in the formula. 3 Due to these
complex factors, the financial and technical barriers to testing
prospective preservatives present a significant hurdle to devel-
opment and adoption of sustainable preservatives in home and
personal care products. This challenge is especially significant for
screening potential alternatives.
To reduce these hurdles, we developed a rapid and inex-
pensive protocol to evaluate the efficacy of promising chemical
Adam P. Byrne, Method Products, PBC and United States Department of Agriculture • William Michael Hart-Cooper, Method
Products, PBC and United States Department of Agriculture; Kaj Johnson, Method Products • Larry H. Stanker, United States
Department of Agriculture • Dominic W. S. Wong, United States Department of Agriculture • William J. Orts, United States
Department of Agriculture
WHAT YOU NEED WHAT YOU DO WHAT YOU SEE
incubate 24+ hours
(depends on challenge organism)
Figure 1: Conceptual Overview of Preservative Screening Protcotcal