Effect of pH on ochratoxin A production by Aspergillus niger aggregate species

Abstract

The effect of pH (2–10) on growth and ochratoxin A (OTA) production by 12 Aspergillus niger aggregate strains was studied in two culture media: Czapek yeast autolysate agar (CYA) and yeast extract sucrose agar (YES), over 30 days. The strains were selected to include different sources, different reported abilities to produce OTA and different ITS-5.8S rDNA RFLP patterns. YES was a better culture medium than CYA for OTA production. In this medium, OTA was produced from pH 2 or 3 to 10 depending on the strain. The results show the ability of A. niger aggregate strains not only to grow, but also to produce OTA over a wide pH range. The results will lead to a better understanding of the role of A. niger aggregate strains in the OTA contamination of several food commodities.

Keywords:

• Aspergillus niger
• coffee
• grapes
• raisins
• ochratoxin A
• pH

Acknowledgements

Research was supported by the Ministerio de Educación y Ciencia of the Spanish Government (AGL2004-07549-C05-03) and by Grant No. 2005 SGR 00684 from the DURSI, Generalitat de Catalunya.