a scale of 0e5 after 4, 8, and 12 wks incubation with 0 indicating no
mould growth and 5 indicating heavy mould growth on all sides of
the specimen.
2.7. ATP assay
An ATP assaywas conducted to confirm that complete inhibition
of metabolic activity occurred in the mould spores following
exposure to isothiazolinone. Adenosine triphosphate (ATP) was
determined using the ATP Lite luminescence detection assay kit
(Perkin Elmer Life Sciences, Boston, MA). Spores (1 106 ml1)
from individual test fungi were incubated with the minimum
inhibitory concentration (MIC90) of isothiazolinone (50 ppm) for
24 h at 37 C. Following incubation, spores were pelleted by
centrifugation (2500 g), washed twice with RPMI to remove
isothiazolinone and assayed for ATP production according to the
ATP Lite assay protocol.