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Microbiol Biotechnol Rep | Volume 1, Issue 2
November 16-17, 2017 Atlanta, Georgia, USA
Annual Congress on
Mycology and Fungal Infections
Genetic diversity of
Aspergillus flavus
and occurrence of aflatoxin contamination in
stored maize across three agro-ecological zones in Kenya
Grace W Gachara
1
, Anthony K Nyamache
1
, Jagger Harvey
2
, Gbemenou Joselin Benoit Gnonlonfin
2
and
James Wainaina
2
1
Kenyatta University, Kenya
2
Biosciences Eastern and Central Africa-International Livestock Research Institute, Kenya
A
flatoxin contamination at post-harvest poses a serious challenge in achieving millennium development goals
on food security especially in the developing world. In Kenya, major outbreaks of aflatoxicoses have been
attributed to poor post-harvest storage practices. In this study, we conducted a cross-sectional survey within three
Agro-ecological zones in Kenya, to determine occurrence and distribution of total aflatoxin in stored maize and
the aflatoxigenicity potential of
Aspergillus flavus
in stored maize. The counties selected were; Kitui, Nakuru
and Kitale (in Trans-Nzoia County). Sampling sites were selected based on previous aflatoxicoses outbreaks
(Kitui) and major maize production areas (Nakuru and Kitale) where little information exists on the occurrence
of aflatoxin contamination. A total of one hundred and thirty (130) kernel maize samples were random collected
during the period between June and August 2012. Moisture content was determined using the standard oven
method and
Aspergillus flavus
was isolated by direct plating technique. Genetic diversity of the isolates was
determined by PCR and Single Sequence Repeats (SSR) micro satellites analysis. Positive strains were induced
to produce B1 aflatoxins on Yeast Extract Sucrose Agar (YESA) and quantified using competitive ELISA
technique. The results indicated mean moisture content of maize ranged between 6% and 34%, although this
was found not to be significantly different (p=0.23>0.05). However, total aflatoxin contamination of postharvest
stored maize samples between sites was significantly different (p=0.000, <0.05); with the highest contamination
in Kitale at a mean of (9.68 µg/kg).
A. flavus
was isolated in 70% (N= 91) of the maize samples collected at
postharvest.
A. flavus
isolates with the highest aflatoxigenicity potential were from Nakuru County with mean
aflatoxin level at 239.7 µg/kg. Genetic distance based on Neighbor Joining (NJ) clustered the
A. flavus
isolates
into five main clusters. Principal coordinate Analysis (PCA) analysis showed five distinct clusters with both axes
explaining 60.17% of the variance. This study showed widespread distribution of aflatoxin contamination and a
highly toxigenic
A. flavus
in stored maize in three major agro ecological zones in Kenya. These results suggest a
potential health risk of aflatoxin outbreaks within these areas, thus call for more investigations.
kikogash@gmail.com