Browsing by Author "Mfaume, Juma"

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Distribution and occurrence of indigenous strains of atoxigenic and toxigenic Aspergillus section Flavi in groundnut producing areas of Southern Tanzania
(Journal of Biodiversity and Environmental Sciences (JBES), 2019-04-28) Mfaume, Juma; Matemu, Athanasia; Mbega, Ernest
The objective of this study was to isolate and identify atoxigenic and toxigenic strains of Aspergillus section Flavi in southern Tanzania, and investigate possible application of atoxigenic strains in control of aflatoxin levels in groundnuts. Fungal communities in soils from groundnut fields were examined to see the distributions of aflatoxin-producing Aspergillus species and to spot endemic atoxigenic strains. Forty-five isolates belonging to Aspergillus section Flavi were collected randomly from soils of groundnut fields in three districts and characterized using morphological and physiological examination. Aspergillus section Flavi was detected in 40/45 (88.89%) of the soil samples collected in Mtwara, Tanzania. Members of Aspergillus section Flavi L-strain was the most common (79.5%), followed by S-strains (18.4%) and finally Aspergillus tamarii (1.8%). The mean colony forming unit (CFU) of the Aspergillus colonies per gram of soil was highly variable (p < 0.05) among the districts, ranging from 8.5×102 to 8.2×103 . The mean pH across the gathering sites additionally varied (pH 5.5- 6.8) which is within the optimal pH requirement for the members of Aspergillus section Flavi. Non-significant (p > 0.05) variation in temperature across the sampling sites was observed. The results also showed that Aspergillus flavus was detected in all the three districts. Atoxigenic strains have a potential value to be employed as biological control agents to mitigate aflatoxin in groundnuts.
Managing aflatoxin – producing fungi using indigenous atoxigenic strains of aspergillus species in groundnut in Mtwara region, Tanzania
(2019-04) Mfaume, Juma
The present study was conducted from January to October 2018 in Mnanje, Mpeta and Naliendele villages to determine aflatoxin levels in dried groundnut kernels, to identify toxigenic and atoxigenic strains of Aspergillus section Flavi from soil samples and to test the effect of atoxigenic strains against aflatoxin-producing fungi in groundnut. Isolation of fungi was done on MRBA and AFPA media and analysis of aflatoxin levels in groundnut was conducted using HPLC. The results showed that, there was significant differences (p < 0.05) in total aflatoxins level between groundnut samples. Eleven (24.4%) out of 45 samples had aflatoxin levels above the Tanzania Food and Drugs Authority’s standard (10 μg/kg). Total aflatoxin contamination levels ranged from higher i.e. 5.86 to 16.81 μg/kg at Mnanje village to lowest at Mpeta village (0.05 to 15.02 μg/kg). The results also indicated that 20.4% of the fungal composition in soil samples were toxigenic strains while 79.5% were atoxigenic implying that these strains can be exploited for biological control to mitigate aflatoxin contamination risks in groundnuts. This was proved through the study that also indicated that total aflatoxin levels in groundnut kernel samples were lower in atoxigenic treated groundnut plots than in controls plots. Thus, there is need to conduct further studies involving a wide geographical location on testing the efficiency of the atoxigenic strains identified in this study for further characterization and formulation of a bio-control against aflatoxin producing- fungi in Tanzania.