Identification Key for Aspergillus Species Isolated from Maize and Soil of Nandi County, Kenya

Citation:
Okoth S. "Identification Key for Aspergillus Species Isolated from Maize and Soil of Nandi County, Kenya." Advances in Microbiology. 2015;5(04):205.

Abstract:

The aim of this study was to identify Aspergillus species isolated from maize kernels and soils of
maize fields of Nandi County using macro and micro morphological characteristics. A cross sectional
research design was used in the study and purposive sampling was employed to determine
districts of Nandi County and sub locations where sampling was done. This study was part of a
larger project whose aim was to survey aflatoxin exposure in the maize value chain. Aspergillus
species were isolated from maize and soil samples using quarter strength potato dextrose agar
and modified Rose Bengal agar respectively. Pure cultures of the isolates were sub cultured and
transferred onto differential media; malt extract agar, czapek yeast extract agar and czapek dox
agar for species identification using macro morphological characteristics. Fungal slides were prepared
from pure cultures on potato dextrose agar media after three days to identify micro morphological
characteristics. Based on morphological characteristics, seven sections of Aspergillus
namely: Flavi, Fumigati, Nigri, Circumdati, Clavati, Nidulantes and Candidi were identified. Aspergillus
section Flavi was the most predominant with 57% followed by section Nigri with 27% from
maize and 58% of section Flavi followed by 26% of section Nigri from the soil across the three locations.
Aspergillus sections Nidulantes and Candidi were rare and only recovered from the soil
samples of Kaptumo location. All the Aspergillius flavus that formed sclerotia both from the soils
or maize kernels were of the L strains. In conclusion Aspergillus section Flavi was most frequent
during the isolation process and dominated with Aspergillus flavus from both the maize and soil.
Morphological characteristics remain the primary tool for detection and identification of Aspergillus
species. The significance for high incidence of Aspergillus section Flavi is in regard to their
aflatoxin production profiles that poses a health threat to the community and it is of public health
concern. Morphological characteristics as a primary tool for Aspergillus identification should be
embraced and more personnel with the knowledge are required since modern and faster techniques
are scarce and expensive.

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