Location: Food and Feed Safety Research
2010 Annual Report
Research on the fungicidal properties of certain soybean volatile compounds, e.g., trans-2-hexenal and trans-2-heptenal, was expanded. Our data showed that, in the volatile state, trans-2-hexenal was superior to trans-2-heptenal volatiles, in preventing Aspergillus flavus growth and aflatoxin (a potent fungally produced carcinogen on crops) production. Even after the pumped trans-2-hexenal ceases to flow, the corn displayed no Aspergillus flavus growth, suggesting that the fungus was killed, not simply inhibited from growing.
Under a Confidentiality Agreement with our stakeholder, Symrise (producer of bisabolol and dragosantol), we expanded our studies of the antimicrobial spectrum of activity of these two compounds known as terpenes. Bisabolol is found in plant oils (e.g., chamomile oil), while dragosantol is the synthetic version of bisabolol. Both are antimicrobial, but are safe for human use. Our attempts to volatilize both compounds for studies in our wet corn/Aspergillus flavus assays (see above) were only partially successful. In future work, we need to develop a better protocol for volatilizing these compounds.
We continued our non-funded research, begun in FY-2009, on the antimicrobial properties of wheat histones (proteins associated with deoxyribonucleic acid) provided to us by our collaborator (University of Lund, Sweden). We found that these histones are highly active against many, but not all fungi. The collaborator’s data suggests that the membrane composition of different species is most likely due to the different sensitivity we see for different microbial genera.
In recent years, the scientific literature has described the use of visible light to kill microorganisms. We began exploratory experiments to determine whether blue light (470nm) could kill several different harmful bacteria (Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus atrophaeus, Leuconostoc mesenteroides) and fungi (Aspergillus flavus, Fusarium verticillioides). The light, alone, kills all the bacteria, but not the fungi. However, blue light in combination with photosensitizing compounds kill fungi.
Our research on determining the secondary metabolic volatiles produced only by toxigenic strains of Aspergillus flavus continues. During FY2010, we reported to our stakeholder, Sensor Development Corporation, the identities of such compounds. Based on our data, the company has developed a “second generation” prototype real-time electronic sensor that will soon undergo Beta testing in grain silos.
Le Blanc, B.W., Davis, O.K., Boue, S., Delucca, A., Deeby, T.A. 2009. Antioxidant Activity of Sonoran Desert Bee Pollen. Journal of Agricultural and Food Chemistry. 115, 1299-1305.
Rajasekaran, K., De Lucca II, A.J., Cary, J.W. 2009. Aflatoxin control through transgenic approaches. Toxin Reviews. 28(2):89-101.
Cornelius, M.L., Lyn, M.E., Williams, K.R., Lovisa, M.P., De Lucca II, A.J., Lax, A.R. 2009. The efficacy of bait supplements for improving the rate of discovery of bait stations in the field by the formosan subterranean termite (Isoptera: Rhinotermitidae). Journal of Economic Entomology. 102(3):1175-1181.