Alemayehu Chala

Aflatoxin B1 and total fumonisin contamination and their producing fungi in fresh and stored sorghum grain in East Hararghe, Ethiopia

ABSTRACT Natural contamination of sorghum grains by aflatoxin B1 and total fumonisin and their producing toxigenic fungi has been studied. A total of 90 sorghum grain samples were collected from small-scale farmers’ threshing floors and 5–6 months later from underground pits during 2013 harvest from three districts of East Hararghe, Ethiopia. Mycotoxin analysis was done using enzyme-linked immunosorbent assay (ELISA). The limits of detection were in the range 0.01–0.03 μg kg–1. The results revealed that all sorghum grain samples were contaminated with both Aspergillus and Fusarium species. Aflatoxin B1 was detected at levels ranging from <LOD to 33.10 µg kg−1 grain. There were marked variations in aflatoxin B1 concentrations between fresh and stored samples, with much higher levels in the latter. Total fumonisin levels varied between 907 and 2041 µg kg−1 grain across the samples. Lowest total fumonisin was recorded in freshly harvested sorghum grain samples. Sorghum is a main staple cereal in the studied districts and its consumption per day per person is high. Daily intake of low doses of mycotoxin-contaminated food stuff over a period of time could lead to chronic mycotoxicosis.

Aspergillus and aflatoxin in groundnut (Arachis hypogaea L.) and groundnut cake in Eastern Ethiopia

ABSTRACT This study was conducted to assess major Aspergillus species and aflatoxins associated with groundnut seeds and cake in Eastern Ethiopia and evaluate growers’ management practices. A total of 160 groundnut seed samples from farmers’ stores and 50 groundnut cake samples from cafe and restaurants were collected. Fungal isolation was done from groundnut seed samples. Aspergillus flavus was the dominant species followed by Aspergillus parasiticus. Aflatoxin analyses of groundnut seed samples were performed using ultra performance liquid chromatography; 22.5% and 41.3% of samples were positive, with total aflatoxin concentrations of 786 and 3135 ng g−1 from 2013/2014 and 2014/2015 samples, respectively. The level of specific aflatoxin concentration varied between 0.1 and 2526 ng g−1 for B2 and B1, respectively. Among contaminated samples of groundnut cake, 68% exhibited aflatoxin concentration below 20 ng g−1, while as high as 158 ng g−1 aflatoxin B1 was recorded. The study confirms high contamination of groundnut products in East Ethiopia.

Multimycotoxin and fungal analysis of maize grains from south and southwestern Ethiopia

ABSTRACT The natural occurrence of fungi, mycotoxins and fungal metabolites was investigated in 100 samples of maize grains collected from south and southwestern Ethiopia in 2015. The maize samples were contaminated by Fusarium, Aspergillus and Penicillium species. Using liquid chromatography tandem mass spectrometry 127 secondary metabolites were analysed. Zearalenone was the most prevalent mycotoxin, occurring in about 96% of the samples. Zearalenone sulfate was the second most prevalent, present in 81% of the samples. Fumonisin B1 was detected in 70% of the samples with a mean level of 606 μg kg−1 in positive samples, while FB2, FB3 and FB4 were detected in 62%, 51% and 60% of the maize samples with mean levels of 202, 136 and 85 μg kg−1, respectively. Up to 8% of the samples were contaminated with aflatoxins, with a maximum level of aflatoxin B1 of 513 μg kg−1. Results were higher than earlier reports for maize from Ethiopia.

Survey of Mango Anthracnose in Southern Ethiopia and In-Vitro Screening of Some Essential Oils against Colletotrichum gloeosporioides

Experiments were conducted to assess the importance of anthracnose in South Ethiopia, characterize isolates of Colletotrichm gloeosporioides, and evaluate the efficacy of essential oils against the pathogen. In 2010, anthracnose incidence and severity were 37–57% and 16–31%, respectively. In 2011, disease incidence ranged from 33% to 65% while severity varied between 17% and 35%. Disease incidence and severity were 77% and 46%, respectively, during market surveys. Mean colony diameters of isolates were 38.6, 48.9, and 51 mm after 48 h of growth at 20, 25, and 30°C, respectively. Oils from Palmarosa and White cumin caused 100% inhibition of fungal growth.

Fungal invasion and mycotoxin contamination of stored sorghum grain as influenced by threshing methods

ABSTRACT Sanitation from harvest to storage is a key factor in eliminating sources of infection and reducing levels of mycotoxigenic fungal invasion, and thereby mycotoxin contamination. This study was conducted at Haramaya University, Eastern Ethiopia to investigate the effects of threshing methods on fungal invasion and mycotoxin contamination of sorghum grain. The methods included threshing on bare ground, cow-dung-painted ground, concrete asphalt and canvas. The threshed grain was kept separately in bags in three replications in a completely randomized design and stored for five months. The results revealed that all the sorghum grain samples taken from different threshing methods were contaminated with both Aspergillus and Fusarium species. There were variations in fungal invasion between samples taken immediately after threshing and stored samples. The level of Aspergillus spp. invasion was much higher in the latter in sorghum grain threshed on bare ground. The concentration of aflatoxin B1 was gradually increased, whereas the total fumonisin concentration was decreased with the storage duration both in 2013 and 2014. On stored sorghum grain, the highest (1.97 µg kg−1) and the lowest (0.70 µg kg−1) mean aflatoxin B1 concentrations were recorded from sorghum grains threshed on bare ground and on canvas, respectively. Sorghum grain obtained from canvas threshing method had significantly lower mean total fumonisin content (142.5, 54.9 µg kg−1) than grain from the other methods at threshing. The current work clearly demonstrated the effect that threshing might have on fungal invasion and mycotoxin contamination of sorghum grains. .