Isolation and Identification of Toxigenic Aspergillus species Associated with Sorghum Grains and Locally Brewed Beer (Burkutu) in Bukuru Metropolis of Jos South Local Government Area, Nigeria

Aim: This study is aimed at Isolating and Identifying the Toxigenic Aspergillus species Associated With Sorghum Grains and Locally Brewed Beer (Burkutu) in Bukuru Metropolis of Jos South Local Government Area, Nigeria.

Methodology: Sorghum grains and locally brewed beer (Burkutu) were collected from three different locations; Gyel, Kugiya, and Doruwa Market of Bukuru Metropolis of Jos South Local Government Area, and Screened for their fungal and total aflatoxin level. The grains were blended for 30 seconds using a high-speed blender. 1 gram of the blended sorghum and 1ml of the Burkutu sample (local beer) were cultured into freshly prepared PDA supplemented with 0.5mg/ml of gentamycin and streptomycin to suppress bacterial growth. This was then incubated at a temperature of 37°C for 72 hours after which various fungi colonies were observed and counted with a colony counter. The fungi isolated were further sub-cultured to obtain pure cultures after which they were classified using conidial morphology as obtained from microscopy. Lactophenol cotton blue mount was also carried out to identify the exact fungi with reference to a mycological atlas. The colony-forming unit for each sample was determined, and the Aflatoxin test was carried out using a Mycotoxin kit (the Rida Quick Scan method) to determine the Total aflatoxin level.

Results: The Aspergillus species found in both Sorghum grains and Burkuru (local beer) were: Aspergillus niger, Aspergillus flavus, and Aspergillus fumigatus. For sorghum grains, Aspergillus niger had the highest frequency of occurrence (42.86%) while Aspergillus flavus & Aspergillus fumigatus occurred equally with (28.57%) respectively. Aspergillus flavus had the highest frequency of occurrence in Burkutu (50%), followed by Aspergillus niger (33.33%) and the least was Aspergillus fumigatus (16.67%). The highest aflatoxin level for grains was detected in Kugiya which had (3.6 parts per billion) followed by the grain sample from Gyel which had (3.0 Ppb) and the least was Doruwa (2.8 Ppb). Burkutu had the highest total level of aflatoxin (3.1Ppb) in the sample from Gyel, followed by Burkutu from Doruwa (2.6 Ppb) and the least was from Kugiya (2.4 Ppb).

Conclusion: Both the sorghum grains and Locally Brewed Beer (Burkutu) collected from the Bukuru Metropolis of Jos South Local Government Area, Nigeria were significantly contaminated by the toxigenic Aspergillus species. This indicates possible health hazards for humans and animals ingesting these substances. However, effective screening of these grains for aflatoxins is advocated to ensure the safety of both grains and their products.