Graduate Research Assistant South Dakota State University Brookings, South Dakota
Glyceollin is a phytoalexin synthesized from the isoflavone daidzein. Both glyceollin and isoflavones such as daidzein have known health benefits to human and animals. Glyceollin production levels vary among different soybean varieties, and fungal strains used can impact glyceollin production in soybeans. In this study, glyceollin expression was induced by fungal inoculation (Trichoderma reesei and Aspergillus sojae) of soaked and dehulled soybeans, which were further allowed to germinate for 120 h. Samples were withdrawn at 0, 24, 48, 72, 96, and 120 h and freeze dried and ground for further analysis. The HPLC s was conducted to determine glyceollin I, II, and II, and isoflavone production. No glyceollin was detected at 0 h, irrespective of soybean variety tested, and fungal strain used. However, glyceollin level started to increase after 24 h of incubation. With the A. sojae as an inoculum, the glyceollin levels were increased by 100-310% at 120 h of incubation as compared to. T. reesei inoculated soybeans. Additionally, soybeans with varying maturity level were tested to determine if soybeans with lower or higher maturity benefited the glyceollin production. Among the varieties tested there was an increase in glyceollin production as maturity increased; for example, the glyceollin concentration of 0.317±0.111 mg/g ay maturity level of 3.5 and 1.349 mg/g glyceollin with the maturity level of 6.9 was achieved with A. sojae inoculated soybeans. If glyceollin can be consistently produced in high quantity, it has the potential to be used as a natural antimicrobial for animal diet, particularly swine.