Effects of temperature and medium composition on inhibitory activities of gossypol-related compounds against aflatoxigenic fungi
Article first published online: 16 MAY 2013
Published . This article is a U.S. Government work and is in the public domain in the USA.
Journal of Applied Microbiology
Volume 115, Issue 1, pages 179–186, July 2013
How to Cite
Mellon, J.E., Dowd, M.K. and Beltz, S.B. (2013), Effects of temperature and medium composition on inhibitory activities of gossypol-related compounds against aflatoxigenic fungi. Journal of Applied Microbiology, 115: 179–186. doi: 10.1111/jam.12219
- Issue published online: 12 JUN 2013
- Article first published online: 16 MAY 2013
- Accepted manuscript online: 18 APR 2013 03:34AM EST
- Manuscript Accepted: 14 APR 2013
- Manuscript Revised: 15 MAR 2013
- Manuscript Received: 28 JAN 2013
- aflatoxin biosynthesis inhibition;
- Aspergillus flavus ;
- Aspergillus parasiticus ;
- natural products;
To investigate the effects of temperature and medium composition on growth/aflatoxin inhibitory activities of terpenoids gossypol, gossypolone and apogossypolone against Aspergillus flavus and A. parasiticus.
Methods and Results
The compounds were tested at a concentration of 100 μg ml−1 in a Czapek Dox (Czapek) agar medium at 25, 31 and 37°C. Increased incubation temperature marginally increased growth inhibition caused by these compounds, but reduced the aflatoxin inhibition effected by gossypol. Gossypolone and apogossypolone retained good aflatoxin inhibitory activity against A. flavus and A. parasiticus at higher incubation temperatures. However, increased temperature also significantly reduced aflatoxin production in control cultures. The effects of the terpenoids on fungal growth and aflatoxin production against the same fungi were also determined in Czapek, Czapek with a protein/amino acid addendum and yeast extract sucrose (YES) media. Growth of these fungi in the protein-supplemented Czapek medium or in the YES medium greatly reduced the growth inhibition effects of the terpenoids. Apogossypolone displayed strong anti-aflatoxigenic activity in the Czapek medium, but this activity was significantly reduced in the protein-amended Czapek and YES media. Gossypol, which displayed little to no aflatoxin inhibitory activity in the Czapek medium, did yield significant anti-aflatoxigenic activity in the YES medium.
Incubation temperature and media composition are important parameters involved in the regulation of aflatoxin production in A. flavus and A. parasiticus. These parameters also affect the potency of growth and aflatoxin inhibitory activities of these gossypol-related compounds against aflatoxigenic fungi.
Significance and Impact of the Study
Studies utilizing gossypol-related compounds as inhibitory agents of biological activities should be interpreted with caution due to compound interaction with multiple components of the test system, especially serum proteins.