The Incidence Of Aspergillus Species And Aflatoxins In Makueni County, Kenya
Ayugi, Vincent O.
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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.