Effect of Temperature on the Growth and Ochratoxin A Production of the Aspergillus section Nigri Members Isolated from Dried Figs

Abstract

AbstractThis study investigated the effects of temperature and incubation time on the growth and ochratoxin A production of three isolates of Aspergillus carbonarius and one Aspergillus niger agg. isolate obtained from dried figs. Optimum growth for all isolates were at 30C while minimum lag phase durations for A. carbonarius isolates were at 25C and for A. niger agg. at 30C. For ochratoxin A (OTA) production, lower optimum temperature values were determined for Aspergillus section Nigri members in comparison to growth temperature. Optimum OTA production was observed at 15–20C and 25C by A. carbonarius and A. niger agg., respectively. Significant amounts of OTA could be accumulated after 3 or 5 days of incubation depending on the isolates. Temperature significantly influenced the growth rate and the extension of lag phase and OTA production of all tested isolates (P < 0.05), whereas incubation time was only significant for OTA production by A. niger agg.Practical ApplicationsThis study contributes to a better understanding of the effect of temperature and incubation time on ochratoxin A (OTA) production of the Aspergillus section Nigri isolated from dried figs. Our results indicated that Aspergillus section Nigri members isolated from dried figs are able to grow and produce OTA in a wide range of temperature (15–40C), and also A. carbonarius may be the main source of OTA in dried figs because of their higher OTA production capacities. Only 3 or 5 days of incubation were required for OTA accumulation, so the length of drying and storage processes could provide sufficient time for the growth and accumulation of OTA in dried figs. Our results may help develop management strategies and drying methods at constant temperature to reduce OTA contamination on dried figs.