Food Safety, Toxicology and Utilization of Contaminated Grain

Barley is affected by Fusarium head blight. The mycotoxins produced by F. graminearum affect the grain safety, malting and beer quality. Barley can be irradiated with electron beam radiation to reduce the fungal contamination, but there may be some Fusarium strains which can survive, grow and produce mycotoxins as irradiated barley is malted. Random amplified polymorphic DNA (RAPD) analysis was done to screen for mutations in Fusarium isolates from irradiated barley. FHB-infected and control barley samples, which were irradiated using electron beam radiation at doses of 0, 2, 4, 6, 8 and 10 KGy were obtained. Fusarium infection (FI) analysis was done on 100 barley seeds which were aseptically placed on half strength potato dextrose agar (HPDA) plates incubated at 25oC for 5 days. Single germinated spores of Fusarium isolates confirmed by FI analysis were transferred to carnation leaf agar and incubated at 25oC for 7 days. The fungal growth on the plates was identified to the species level microscopically based on morphological characteristics. The morphology, pigment and growth of these fungal colonies were confirmed by growing conidia of Fusarium isolates on HPDA plates which were incubated at 25oC for 7 days. Nine F. graminearum isolates were used for RAPD analysis to screen for mutations by comparing with a control F. graminearum isolate (FRC R9821) and were grown on 25 g of autoclaved rice (40% moisture content) at 25oC for 14 days and analyzed for their ability to produce deoxynivalenol and related mycotoxins by high pressure liquid chromatography. The cluster analysis of the various F. graminearum isolates’ RAPD profiles have confirmed that they can be divided into two groups. Group A consists of the reference strain (FRC R-9821) and four isolates obtained from control and irradiated (2KGy) barley. Group B consists of three isolates which were obtained from barley irradiated to 4, 6 and 10 KGy and two control strains. Deoxynivalenol (DON) produced by both control and irradiated isolates ranged from none to 31.1 μg and 15-Acetyl deoxynivalenol (15-ADON) produced ranged from none to 105.34 μg. Some of the isolates obtained from irradiated barley retained their DON producing ability to some extent (ranged from 0.65-4.76 μg) but produced no ADON. The results from mycotoxin analysis indicate that irradiation may decrease mycotoxigenesis in F. graminearum. Further research has to be done to know whether irradiated barley can be used in malting industry, as irradiation is found to reduce the mycotoxigenecity of F. graminearum isolates obtained from irradiated barley.