Effect of sorghum (Sorghum bicolor L. Moench) grain conditions on occurrence of mycotoxin-producing fungi

Abstract

Sorghum is a staple cereal crop that is well adapted to arid and semi-arid lands (ASALs). It has a potential of assuring food security and livelihoods in the ASALs. The objective of this study was to determine the effect of sorghum grain conditions on occurrence of mycotoxin-producing fungi. Two kilograms of sorghum grains were sampled from the breeder’s crop at Egerton University research field and at a farmer’s field at Kampi Ya Moto. Sorghum was sampled at dough stage and at physiological maturity. Sorghum grains sampled at dough stage were divided into three sets. Set one was immediately examined for fungi; set two was sun dried for 21 h and set three was stored for a fortnight before being examined for fungi. Grains were plated on potato dextrose agar medium and incubated at 25 ± 2 °C for 7 days. Fungal colonies growing were sub-cultured and identified using a microscope and a standard mycological catalogue based on micro- and macro-morphological features. Identified fungi were Aspergillus, Penicillium and Fusarium species. Aflatoxins were detected in 37 samples using reverse-phased HPLC at a wavelength of 365 nm. The aflatoxin B1, B2, G1 and G2 were detected in 10.81, 5.41, 18.92 and 32.43 % of the samples, respectively. There was no aflatoxin detected on 32.42 % samples. These results would contribute to reduced risk of mycotoxin-producing fungi in sorghum grain, minimize grain losses and improve grain quality among smallholder farmers in sorghum growing areas. Aspergillus, Fusarium and Penicillium species of fungi do occur in sorghum grain both in the field and in the store.