INFLUENCE OF SORBIC ACID ON VIABILITY AND ATP CONTENT OF CONIDIA OF Aspergillus parasiticus

Abstract

ABSTRACTThe objective of this work was to determine viability and ATP content of conidia of Aspergillus parasiticus NRRL 2999 following exposure to sorbic acid solutions. The minimum inhibitory concentration of sorbic acid to A. parasiticus conidia was found to be between 0.05 and 0.10% (w/v). The viability of conidia remained constant during the first 12 hr of exposure to 0.25% sorbic acid. From 12–20 hr of exposure, a slow decline in viability became evident with a rapid decline occurring after 20 hr of exposure. When the concentration of sorbic acid was increased from 0.25 to OS%, viability of the conidia was greatly reduced and the time required for viability to decrease dropped from 20 hr to 4 hr. When ATP levels of conidia were studied, there was a rapid decline in ATP during the fist 24 hr of exposure to 0.22% (0.02M) sorbic acid, followed by a more gradual decline from 24–36 hr. At a sorbic acid concentration of 0.34% (O.O3M), the same pattern of decreasing ATP was seen, but the decline was much more rapid and the ATP concentration reached a much lower level. The data showed that the decrease in ATP level of the conidia could be related to decreased viability of the conidia after exposure to sorbic acid. This suggests that one possible mechanism of action of sorbic acid in fungal inhibition may involve depletion of ATP levels of conidia.