Abstract

Aflatoxin contamination of maize put the health and well-being of Kenyan people at risk, primarily children. Aflatoxigenic fungi can infect grains from pre-harvest stages in the field to post-harvest stages in the stores. The aim of this study was to isolate and characterize aflatoxigenic Aspergillus spp. from maize and soil samples from selected counties of Kenya: Makueni, Nyeri, Bungoma, Uasin Gishu and Siaya. Isolation was done using the direct plating technique of surface-sterilized grains on Czapek Dox Agar medium and plating of serially diluted soil samples. Aspergillus colonies were purified and identified using colony growth characteristics, colony colour on PDA media and microscopic characterisation. In total, 174 Aspergillus isolates were obtained, where 82.3% came from maize samples while 17.7% were from soil samples. Makueni County had the highest number of Aspergillus isolates at 58.1%, Nyeri 12.6%, Uasin Gishu 10.3%, Siaya 10.3% and Bungoma 8.6%. The characterization process identified 10 different Aspergillus spp.; 78.5% were Aspergillus flavus, 8.0% A. versicolor, 3.4% A. parasiticus, 2.3% A. clavatus, 2.3% A. sydowii, 2.3% A. fumigatus, 1.1% A. glaucus, 1.1% A. nidulans, 0.6% A. candidusand 0.6% A. wentii.  The results evidence that maize grains and fields in the various counties are highly contaminated with aflatoxigenic Aspergillus species.

Key words: Aflatoxin, Aspergillus, maize.

Abbreviation

PDA, Potato dextrose agar; CZ, Czapek Dox Agar; ANOVA, analysis of variance.