Wagacha, JM, Mutegi CK, Christie ME, Karanja LW, Kimani J.  2013.  Changes in Fungal Population and Aflatoxin Levels and Assessment of Major Aflatoxin Types in Stored Peanuts (Arachis hypogaea Linnaeus). Journal of Food Research. 2(5):10-23.
Ndung'u, JW, Makokha AO, Onyango CA, Mutegi CK, Wagacha JM, Christie ME, Wanjoya AK.  2013.  Prevalence and potential for aflatoxin contamination in groundnuts and peanut butter from farmers and traders in Nairobi and Nyanza provinces of Kenya. Journal of Applied Biosciences . 65:4922–4934.
Mutegi, CK, Wagacha JM, Christie ME, Kimani J, Karanja L.  2013.  Effect of storage conditions on quality and aflatoxin contamination of peanuts (Arachis hypogaea L.). International Journal of AgriScience. 3:746-758.
Wagacha, JM, Mutegi C, Karanja L, Kimani J, Christie ME.  2013.  Fungal species isolated from peanuts in major Kenyan markets: Emphasis on Aspergillus section Flavi. Crop Protection. 52:1-9. Abstract

A survey was conducted in Nairobi, Nyanza and Western provinces in Kenya between March and July 2009 with 1263 peanut products sampled out of which 705 samples underwent microbial analysis. The study aimed at determining the incidence of fungal species - emphasis on Aspergillus section Flavi - associated with peanut products. A 0.5kg representative sample was obtained from each surveyed vendor and the colony forming units (CFU) of fungal species determined. The samples were also analyzed for total aflatoxin level while isolates of A. flavus and A. parasiticus were screened for production of aflatoxin B1, B2, G1 and G2. Eight fungal species were detected in the samples and were in decreasing order of CFU/g of sample: A. flavus S-strain (467), A. flavus L-strain (341), Penicillium spp. (326), A. niger (156), A. tamari (27), A. alliaceus (21), A. parasiticus (10), and A. caelatus (5). The overall incidence of A. flavus S-strain in samples from Nairobi was 92 and 1425% higher than samples from Nyanza and Western regions, respectively. The combined incidence of A. flavus and A. parasiticus was varied significantly (p ≤ 0.05) with peanut product: peanut flour (69%), shelled raw peanuts (53%), spoilt peanuts (49%), boiled podded peanuts (45%), podded peanuts (39%), peanut butter (31%), fried peanuts (22%) and roasted peanuts (20%). Seventy three percent of A. flavus and A. parasiticus isolates produced at least one of the aflatoxin types, with 66% producing aflatoxin B1. The total aflatoxin level among peanut products ranged from 0 – 1629 µg/g; and there was a positive correlation (r = 0.2711) between the incidence of A. flavus and A. parasiticus, and total aflatoxin level. The high incidence of aflatoxin producing fungi in peanuts traded in Kenyan markets implies a risk of aflatoxin contamination, highlighting the need for stakeholders to promote sound practices at all stages of the peanut value chain in order to minimize market access by non-complying products.

Keywords: Aflatoxin; Aspergillus section Flavi; fungal species; peanuts.

Nyirahakizimana, H, Mwamburi L, Wakhisi J, Mutegi CK, Christie ME, Wagacha JM.  2013.  Occurrence of Aspergillus Species and Aflatoxin Contamination in Raw and Roasted Peanuts from Formal and Informal Markets in Eldoret and Kericho Towns, Kenya . Advances in Microbiology. Abstract

The population and diversity of fungal species and levels of aflatoxin contamination were investigated in 228 marketed peanut samples; 140 from formal and 88 from informal markets, in Kericho and Eldoret towns of Kenya. Ground peanut samples were cultured on Modified Dichloran Rose Bengal (MDRB) agar while aflatoxin level was quantified based on indirect competitive ELISA. Correlation between the incidence of major aflatoxin-producing fungal species and aflatoxin levels was also established. Fungal species commonly isolated from the peanut samples included Aspergillus flavus L strain, A. flavus S strain, A. parasiticus, A. tamarii, A. caelatus, A. alliaceus (all of Aspergillus section Flavi) and A. niger. Fungi isolated in low frequency included Fusarium spp., Penicillium spp., Mucor spp. and Rhizopus spp. Aflatoxin levels in peanut products ranged from 0 to 2345 μg/kg in raw peanuts, 0 to 382 μg/kg in roasted coated peanuts, and 0 to 201 μg/kg in roasted de-coated peanuts. Overall, levels of total aflatoxin were higher in samples from informal (mean = 97.1 μg/kg) than formal (mean = 55.5 μg/kg) market outlets. There was a positive and significant correlation (R2 = 0.63; p ≤ 0.05) between aflatoxin levels and the major aflatoxin producing fungi in raw peanuts from formal markets in Eldoret town. Additionally, total aflatoxin in raw peanut samples from informal markets in Kericho was positively and significantly correlated (R2 = 0.81; p ≤ 0.05) to the population of A. flavus (L and S strains). In roasted coated peanuts sampled from formal market outlets in Eldoret, aflatoxin levels correlated positively and significantly (R2 = 0.37; p ≤ 0.05) with A. flavus S strain. There is need to create awareness among peanut traders and consumers on proper handling of peanuts and health risks associated with consumption of unsafe peanut products.

Mutegi, C, Wagacha JM, Kimani J, Otieno G, Wanyama R, Hell K, Christie ME.  2013.  Incidence of aflatoxin in peanuts (Arachis hypogaea Linnaeus) from markets in Western, Nyanza and Nairobi Provinces of Kenya and related market traits. Journal of Stored Products Research. 52:118-127.


Musyimi, SL, Muthomi JW, Narla RD, Wagacha JM.  2012.  Efficacy of biological control and cultivar resistance on Fusarium Head Blight and T-2 Toxin contamination in Wheat. American Journal of Plant Sciences . 2:393-402.
Wagacha, JM, Oerke E-C, Dehne H-W, Steiner U.  2012.  Interactions of Fusarium species during prepenetration development. Fungal Biology. 5:581–590.
Gachu, SM, Muthomi JW, Narla RD, Nderitu JH, Olubayo FM, Wagacha JM.  2012.  Management of thrips (Thrips tabaci) in bulb onion by use of vegetable intercrops. 2:599-607.
Muthomi, JW, Musyimi SL, Wagacha JM, Narla RD.  2012.  Occurrence of Fusarium species and associated T2-toxin in Kenyan wheat. Agricultural Sciences. 3:24-34.


Wagacha, JM, Steiner U, Dehne H-W, Zuehlke S, Spiteller M, Muthomi J, Oerke E-C.  2010.  Diversity in Mycotoxins and fungal species infecting wheat in Nakuru District, Kenya. Journal of Phytopathology. 157:527–535.: Journal of Phytopathology 157: 527 Website


Muthomi, JW, Otieno PE, Cheminingw’a GN, Nderitu JH, Wagacha JM.  2008.  Effect of chemical spray on insect pests and yield quality of food grain legumes. Journal of Entomology. 5:156–163.
Muthomi, JW, Ndungú JK, Gathumbi JK, Mutitu EW, Wagacha JM.  2008.  The occurrence of Fusarium species and mycotoxins in Kenyan wheat. Crop Protection. 27:1215–1219.
Mutitu, EW, Wagacha JM, M MJ, B. MF.  2008.  Control of bean rust on snap beans (Phaseolus vulgaris L.) using antibiotic metabolites produced by Bacillus and Streptomyces species. Botswana Journal of Agriculture and Applied Sciences. 4:62-69.
Riungu, GM, Muthomi JW, Narla RD, Wagacha JM, Gathumbi JK.  2008.  Management of Fusarium head blight of wheat and deoxynivalenol accumulation using antagonistic microorganisms. Plant Pathology Journal. 7:13-19.
Muthomi, JW, Riungu GM, Ndungú JK, Narla RD, Gathumbi JK, Wagacha JM.  2008.  Head blight of wheat in Kenya and contamination of grain with mycotoxin producing Fusarium species. Journal of Plant Sciences . 3:52-60.: Journal of Plant Sciences 3: 52 - 60Website
Wagacha, JM, Muthomi JW.  2008.  Mycotoxin problem in Africa: Current status, implications to food safety and health and possible management strategies. Journal of Food Microbiology . 124:1-12.: International Journal of Food Microbiology 124: 1-12Website


Muthomi, JW, Ndungú JK, Chemining´wa GN, Wagacha JM.  2007.  Reaction of some Kenyan wheat cultivars to head blight after inoculation with Fusarium graminearum. Asian Journal of Plant Sciences . 6:585-591.
Wagacha, JM, Muthomi JW, Mutitu EW, Mwaura FB.  2007.  . Control of bean rust using antibiotics produced by Bacillus and Streptomyces species - Translocation and persistence in snap beans. Journal of Applied Sciences and Environmental Management . 11:165–168.
Muthomi, JW, Otieno PE, Chemining´wa GN, Nderitu JH, Wagacha JM.  2007.  Effect of root rot pathogens and fungicide seed treatment on nodulation and biomass accumulation. Journal of Biological Sciences. 7:1163-1170.
Wagacha, JM, Muthomi JW.  2007.  Fusarium culmorum: Infection process, mechanisms of mycotoxins production and their role in pathogenesis in wheat. Crop Protection . 26:877-885.: Crop Protection 26: 877-885Website



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