Viability of Fungal Spores Isolated from Sorghum Grains Sampled from the Field, Market and Different Storage Facilities in the Six Agro-ecological Zones of Nigeria

Abstract

Nutritional quality, organoleptic attributes and food safety are usually compromised by the presence of Microscopic fungi or fungal spores in food and feeds that humans and animals solely rely on. It is therefore intended in this study to re appraise the viability of fungal spores in sorghum from different ecosystems in Nigeria with a view to establish the level of infection/contamination and also to establish a basis for predicting the possible mycotoxins that may likely be present in sorghum obtained from the study areas. Sorghum sample was collected from six Agro ecological zones of Nigeria. Each zone was transversely delineated into districts and five villages (at least 20 Km from each other) called locations were selected in each district. In each district, Sorghum grains in stores, bunches in the field and sorghum grains in the market were sampled from five locations, each approximately 20 km from the previous sampling location. The mycological analytical procedures were performed under aseptic condition. One gram of milled sample was weighed into a test tube and diluted in 9 ml of sterile Ringer’s solution, vortexed and serially diluted further to 10-6. One ml from each test tube was cultured by pour plate technique on Ohio Agricultural Station agar (OAESA) and potato dextrose agar (PDA) and incubated for 4-7 days at 25°C. Plates were counted for fungal colonies using a colony counter and the number of fungal colonies per gram of sample was calculated and expressed in colony forming units per gram of sample. The fungi species were isolated and subsequently identified using MEA/CYA media for Aspergillus and Penicillium species and PDA for the fusarium species. It was observed that: the count range in all the samples from all the ecological zones is far above the standard Mycological poor quality standard of 7 x 104. The highest value of 1.3x 108 and the lowest value of 6.7x 106 all which outrageously exceed the bad quality range were obtained. This is a clear indication that people subsisting on sorghum and sorghum based products are at a high risk of exposure to both Mycoses and Mycotoxicosis in all the Agro ecological zone of the country and the traditional storage system seems infective in curtailing fungal proliferation in the studied area.