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Substrate utilization by Aspergillus flavus in inoculated whole corn kernels and isolated tissues
Jay E Mellon1, Michael K Dowd, Peter J Cotty
1Southern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, P.O. Box 19687, New Orleans, Louisiana 70179, USA. jmellon@srrc.ars.usda.gov
Journal of Agricultural and Food Chemistry
|March 17, 2005
Summary
Aspergillus flavus infection depletes corn (Zea mays) saccharides and triglycerides, producing aflatoxin B1. The fungus targets germ tissue, utilizing sugars first, then fats.
Area of Science:
- Agricultural Science
- Mycology
- Biochemistry
Background:
- Aspergillus flavus (A. flavus) is a significant pathogen affecting corn (Zea mays) kernels.
- Understanding nutrient utilization by A. flavus is crucial for managing aflatoxin contamination.
Purpose of the Study:
- To investigate the utilization of major reserve materials in corn kernels by A. flavus during infection.
- To monitor aflatoxin B1 production and identify preferential nutrient substrates.
Main Methods:
- Detached corn kernels were inoculated with A. flavus and monitored over 12 days.
- Concentrations of saccharides, starch, triglycerides, and zein were quantified.
- Aflatoxin B1 levels and polyol production were measured.
Main Results:
- Inoculated kernels showed rapid depletion of sucrose, raffinose, and triglycerides compared to non-inoculated controls.
- Starch and zein remained stable; aflatoxin B1 increased significantly in inoculated kernels.
- A. flavus produced polyols (erythritol, arabitol, mannitol) and preferentially utilized saccharides, then triglycerides, targeting germ tissue.
Conclusions:
- A. flavus efficiently metabolizes readily available carbon sources in corn germ tissue.
- Nutrient availability and tissue localization influence fungal growth and aflatoxin production.
- Selective nutrient utilization by A. flavus impacts corn kernel integrity and safety.