Comparative studies on the changes of total soluble proteins and protease activity in Georgian commercial peanuts contaminated by Aspergillus flavus

Abstract

The presence of Aspergillus species is an indicator of storage conditions, which also suggests the possibility of several biochemical changes in grains. A comparative change in total soluble proteins and protease activity was determined in commercial peanut seeds collected from Georgia State. Protein contents of healthy peanuts, naturally contaminated peanuts and then artificially inoculated peanut seeds with A. flavus were estimated by Bradford method, and protease activity was also determined by using the Protease Detection Kits. Protein contents and the protease activity of the peanuts varied from sample to sample. The soluble protein content of seeds was significantly higher in healthy peanuts than in artificially inoculated or naturally infected peanuts with A. flavus. Protease activity was found to be higher in artificially inoculated seeds than in either naturally infected or healthy peanuts. Level of soluble proteins in buffer extracts of contaminated seeds decreased with incubation time, and protease activity increased with incubation time. These changes may be attributed to host response due to infection, contribution by A. flavus or due to biochemical alterations that occur naturally during the transition from endosperm to seedling during incubation period.

Keywords:

• Aspergillus
• fungal contamination
• peanuts
• protease activity
• soluble proteins

Acknowledgements

We would like to thank Department of Biology and Physics, Kennesaw State University for financial support, Dr K. Gwantney for his expertise with the fluorometer for protein and protease essay. Our special thanks to Daniel Kupsky, research assistant from SALT program, KSU.