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Inhibition of
growth of some phytopathogenic and mycotoxigenic fungi by
aqueous extracts of Combretum imberbe (Wawra) wood
Peloewetse E.1*, Thebe M. M.2,
Ngila
J. C3. and Ekosse G. E.4
1Department
of Biology, University of Botswana, Faculty of Science,
Private Bag 00704 Gaborone, Botswana.
2Lobatse
Secondary School, Private Bag 13 Lobatse, Botswana.
3School
of Chemistry, University of KwaZulu-Natal, Westville Campus,
Private Bag X54001 Westville, Durban 4000, South Africa.
4School
of Physical and Mineral Sciences, University of Limpopo,
Private Bag X1106, Sovenga 0727 , South Africa.
*Corresponding author. E-mail:
peloewee@mopipi.ub.bw.
Tel: (+267) 3552604.
Accepted 26 June, 2008 |
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Fungal attack of crop plants and the associated
production of mycotoxins on edible produce from plants is a
global concern. This is so because mycotoxins are
carcinogenic. This study reports on an investigation of the
effects of aqueous extracts of Combretum imberbe wood
ash on the growth of some phytopathogenic and mycotoxigenic
fungi including Aspergillus flavus, Fusarium
oxysporum, Penicillium italicum, Penicillium
notatum as well as Alternaria alternata. The
aqueous extract of C. imberbe wood ash exhibited
significant capacity to inhibit growth of all the test
fungi, with the exception of A. alternata. Arrest of
fungal growth by the extract involved inhibition of
glucomamylase. Investigation of the chemistry of the ash
using Fourier-Transform Infrared (FT-IR) spectroscopy and
X-ray powder diffraction (XRPD) analysis revealed the
presence of aluminium oxide (Al2O3),
calcium carbonate (CaCO3), calcium hydroxide
(Ca(OH)2), potassium chloride (KCl), potassium
sulphate (K2SO4) and cobalt carbonate
(CoCO3). We propose that the inhibition of fungal
growth may be related to limited carbon supply as a result
of inhibited activity of glucoamylase in the presence of
C. imberbe wood ash extract.
Key words:
Adaptive response, alkalization, Combretum imberbe,
glucoamylase, mycotoxins. |
