Effects of temperature and incubation time on growth and ochratoxin A biosynthesis by Aspergillus carbonarius and Aspergillus ochraceus in grain-based media

Abstract

Ochratoxin A (OTA) has been frequently found as a food contaminant, and it is considered one of the mycotoxins most harmful to human health. In this context, this study was performed aiming to evaluate mycelial growth and ochratoxin A production from three isolates of Aspergillus carbonarius and Aspergillus ochraceus. The isolates were inoculated on culture media coffee, wheat and maize as well as YES medium and cultivated at 15 and 25°C. Measurement of colony diameters was performed every 48 h for growth description. OTA quantification was made with high-performance liquid chromatography (HPLC) three times (5th, 15th and 25th day). All the isolates presented higher growth rate in YES medium at 25°C; however, growth in every culture media at both tested temperatures was observed. The maize-based medium showed the lowest growth rate. YES medium induced the most OTA production. In grain-based culture media, A. ochraceus isolates produced lower quantities of OTA, reaching a maximum of 9.95 µg/g. However, A. carbonarius isolates produced much higher quantities, showing the A. carbonarius CCDCA10608 isolate, which produced 29.83 µg/g at 15°C in YES medium and 13.06 in wheat-based medium at 15°C. Therefore, among the tested conditions, those more and less favorable to OTA production were recognized.