TITLE:
Identification Key for Aspergillus Species Isolated from Maize and Soil of Nandi County, Kenya
AUTHORS:
Beatrice Wabusya Nyongesa, Sheila Okoth, Vincent Ayugi
KEYWORDS:
Aspergillus, Morphological Keys, Maize, Soil, Nandi, Kenya
JOURNAL NAME:
Advances in Microbiology,
Vol.5 No.4,
April
1,
2015
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.