| dc.description.abstract | Aspergillus species along with other fungal genera such as Fusarium, Penicillium and Trichoderma are a
group of fungal organisms that are a major cause of degradation of agricultural products both before
and after harvest, and which have the capacity to produce mycotoxins. Aflatoxin is the most rampant
mycotoxin in Makueni County with the major aflatoxin producers being Aspergillus flavus, A. parasiticus
and A .nomius. Aflatoxin B is known to be the most toxic aflatoxin, capable of causing acute
aflatoxicosis.
During the course of this research, the presence and population of Aspergillus species were studied in
various households in Makueni County, Kenya. A total of 292 households across three locations were
sampled to determine the distribution of Aspergillus species. Isolates were recovered from soil and grain
samples using Modified Rose Bengal Agar (MRBA) and Potato Dextrose Agar (PDA) media. Based on
macroscopic and microscopic criteria, four sections ( Flavi, Nigri, Circumdati and Fumigati) were
identified.The taxonomic identification of fungal genera present on maize grain and soil was carried out.
Aspergillus isolates were initially identified to the genus level using PDA then to the species level using
the differential culture media that eventually generated a taxonomic key. ,
Similarly, this study aimed to identify, characterize and establish the ability of toxigenic strains of
Aspergillus species to produce aflatoxins in Makueni County. Characterization of species was based on
morphological as well as molecular features. Molecular characterization of 2 genes of biosynthetic
pathways aflD and aflQ were tested for presende and expression by PCR. Coconut cream agar and
LCMSMS experiments were carried out to determine if the toxigenic strains were actually able to produce
aflatoxins, while ELISA was carried out to detect the presence and levels of aflatoxin in maize kernels.
Maize and sorghum samples across Makueni County exhibited high mould contamination incidences,
with some maize kernels containing more than one colony of fungi as part of their internal mycoflora.
Description of variability within Aspergillus species in Makueni County would therefore facilitate efforts
to define the extent of grain contamination in the region. Study of the incidence and prevalence of
aflatoxin- producing strains of Aspergillus is essential because of the frequent outbreaks of acute aflatoxin
poisoning that have been reported in parts of Eastern province and its environs. There was a high
incidence of aflatoxigenic strains of Aspergillus species coupled with their ability to produce extremely
high levels of aflatoxin. In addition, aflatoxin beyond the set national limits of 10ppb was detected 111
maize kernels.
Maize is a staple diet for many households in Kenya and the presence of such high fungal population
densities in addition to high aflatoxin production levels exposes households to ill health and loss of
income which in turn impacts negatively on the food security of the country. Thus, mitigation and
management strategies should be targeted towards the whole fungal community. | en |
