Identification and Toxigenicity of Aspergillus spp. from Soils Planted to Peanuts in Eastern Zambia

Njoroge, S M C and Kanenga, K and Siambi, M and Waliyar, F and Monyo, E S (2016) Identification and Toxigenicity of Aspergillus spp. from Soils Planted to Peanuts in Eastern Zambia. Peanut Science, 43 (2). pp. 148-156. ISSN 0095-3679

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Abstract

It is not known which aflatoxigenic species are present in Zambia. Therefore, soil samples were collected during May to June 2012, at the end of the growing season in Eastern Province, from 399 farmers' fields that had been planted to groundnut (Arachis hypogaea L.) in Nyimba, Petauke, Mambwe, and Chipata Districts. Population densities of Aspergillus spp. were estimated by plating 10−3 soil dilutions on modified dichloran rose Bengal (MDRB) media. To test for toxigenicity, colonies were randomly selected from MDRB dilution plates, single-spored, transferred to vials with yeast extract sucrose (YES) liquid media, and grown for a week at room temperature. Agra Strip ® lateral flow cards were then used to test the filtered extracts, from the YES cultures, for total aflatoxin at 4 and 20 parts per billion (ppb). We identified Aspergillus flavus (small and large sclerotia strains), A. parasiticus, A. niger, A. nomius, A. oryzae, A. tamarii, and A. terreus. 100% of the S-strain A. flavus isolates produced aflatoxin at 4 and 20 ppb, whereas 86% and 56% of the L-strain A. flavus isolates produced aflatoxins at 4 and 20 ppb, respectively. All the A. nomius isolates produced aflatoxins at 4 and 20 ppb. 79% and 64% the A. parasiticus isolates produced aflatoxins at 4 and 20 ppb. To our knowledge, this is the first peer reviewed report from Zambia documenting the population densities of A. flavus across different agroecologies. In addition, it is also the first report on the identification of different Aspergillus spp., such as A. nomius, A. terreus, A. oryzae, and A. tamarii from Zambia. This information, taken together with cropping practices, soil characteristics, agroecological and climatic data, can form a basis for developing holistic pre-harvest aflatoxin mitigation strategies.

Item Type: Article
Divisions: Research Program : East & Southern Africa
CRP: CGIAR Research Program on Agriculture for Nutrition and Health
CGIAR Research Program on Grain Legumes
Uncontrolled Keywords: Aflatoxins, Aflatoxigenic species, Zambia, Aspergillus spp, Peanuts, Eastern Zambia, Toxigenicity, Aflatoxigenic, Population densities
Subjects: Others > Zambia
Mandate crops > Groundnut
Others > Aflatoxins
Others > East Africa
Depositing User: Mr Ramesh K
Date Deposited: 22 Feb 2017 05:12
Last Modified: 22 Feb 2017 05:13
URI: http://oar.icrisat.org/id/eprint/9891
Official URL: http://dx.doi.org/10.3146/PS15-11.1
Projects: UNSPECIFIED
Funders: UNSPECIFIED
Acknowledgement: We thank Joseph Maruwo (ICRISAT-Malawi), Dickson Mbughi (ICRISAT-Malawi), Willard Sinkala (Zambia Agriculture Research Institute-Msekera Station), and Griven Phiri (Zambia Agriculture Research Institute-Msekera Station) for technical support. This research was funded by USAID Feed the Future project on Aflatoxin Mitigation in Zambia, grant number EEM-G-00-04-0003-00 modification # 11/12. The study was carried out as part of CGIAR Research Program on Grain Legumes and also as part of CGIAR Research Program on Agriculture for Nutrition and Health.
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