Occurrence of aflatoxins and aflatoxin-producing Aspergillus spp. associated with groundnut production in subsistence farming systems in South Africa

Anatoxins are carcinogenic mycotoxins produced by Aspergillus spp. In groundnut kernels. Forty-six groundnut samples were collected from subsistence farmers In three provinces of South Africa, namely KwaZulu-Natal (KZN), Mpumalanga (MP) and Limpopo (LP), in 2006 and 2007. Anatoxin levels of groundnut kernels were quantified using an ELISA technique. The occurrence of A. parasiticus colonies was predominant and it was isolated at twice the frequency of A. flavus. Anatoxins were present in groundnut produced in the northern parts of KZN, where aflatoxin levels of up to 131 parts per billion (ppb) were found. In Mpumalanga and Limpopo, the highest aflatoxin levels were 160 ppb and 2 ppb, respectively. In the Makhanisi and Mbazwane localities situated in KwaZulu-Natal, and in Boshoffontein in Mpumalanga, aflatoxin levels were higher than the maximum permitted level set by the Food and Drug Administration in the USA (20 ppb), the European Union (6 ppb) and the Department of Health in South Africa (10 ppb) for groundnut that is Intended for direct human consumption. This study indicates the need for mycotoxin awareness campaigns and control programs to be implemented in rural areas of South Africa.Articl

Nitrogen utilisation and growth at reduced water activity by mucoralean fungi present in soil

Nine mucoralean fungal genera including 18 species were examined for their ability to utilise a series of nitrogen containing compounds and to grow at an a(w) of 0.955 on solid media. The nitrogen concentration in the media was 0.1 g/l and the series of nitrogen containing compounds were ammonium chloride, asparagine, sodium glutamate, sodium nitrite and potassium nitrate. The genera were Actinomucor Schostak., Backusella Hesselt. and J.J. Ellis, Cunninghamella Matr., Gongronella Ribaldi, Mortierella Coem., Mucor Fresen., Rhizomucor Lucet and Costantin., Rhizopus Ehrenb. and Thamnostylum Arx and H. P. Upadhyay. Thirty-nine fungal strains obtained from culture collections (CBS, MUFS and PPRI), as well as 12 soil isolates from the Karoo, were tested. All the species and strains tested in this study were able to utilise asparagine and glutamate. Strains belonging to Cunninghamella, Mucor racemosus Fresen., Rhizopus microsporus Tiegh. and Rhizopus stolonifer (Ehrenb.: Fr.) Vuill. were unable to utilise ammonium chloride. Strains of Cunninghamella, Mortierella, Rhizomucor, Rhizopus microsporus and Rhizopus stolonifer were unable to grow on nitrate as sole nitrogen source. Nitrite was found to be toxic to species belonging to Cunninghamella, Mortierella, Rhizomucor, Rhizopus and Thamnostylum. Members of Gongronella, Mortierella, Mucor racemosus, Rhizomucor and Thamnostylum were unable to grow at an a(w) of 0.955.Articl

Fusarium spp. and levels of fumonisins in maize produced by subsistence farmers in South Africa

Fusarium spp. produce fumonisins - mycotoxins that are of importance to maize production in South Africa. Fumonisins have been associated with human oesophageal cancer and cause various diseases in animals that are of concern to the animal feed industry. Maize samples, collected from subsistence farm fields in the Eastern Cape, KwaZulu-Natal, Limpopo and Mpumalanga provinces of South Africa during the 2006 and 2007 growing seasons, were analysed for Fusarium spp. and contamination with fumonisins. Fusariumverticillioides was the most common Fusarium species in maize followed by F. subglutinans and F. proliferatum. Levels of contamination with fumonisins ranged from 0 µg/g to 21.8 µg/g, depending on the region where samples were collected. Levels of fumonisins were highest in northern KwaZulu-Natal (Zululand) where 52% and 17% of samples collected in 2006 and 2007, respectively, exceeded 2 µg/g. Regression analyses showed a positive correlation between fumonisin-producing Fusarium spp. determined by real-time polymerase chain reaction and concentration of fumonisins (r = 0.93). Many samples from Zululand, and some from Mokopane (Limpopo) and Lusikisiki (Eastern Cape), contained fumonisins at levels well above the maximum levels of 2 µg/g set by the Food and Drug Administration (USA) and therefore also the limit of 1 µg/g set by the European Union for food intended for direct human consumption. Regulations governing contamination of grain with fumonisins are not yet implemented in South Africa. The high incidence of fumonisins in subsistence farming systems indicates the need for awareness programmes and further researc

Occurrence of aflatoxins and aflatoxin-producing Aspergillus spp. associated with groundnut production in subsistence farming systems in South Africa

Abstract: Author: Ncube, E. Flett, B.C. Waalwijk, C. Viljoen, A. Vol 27 Issue 2 Publication: 2010 Page: 195-198 : Aflatoxins are carcinogenic mycotoxins produced by Aspergillus spp. in groundnut kernels. Forty-six groundnut samples were collected from subsistence farmers in three provinces of South Africa, namely KwaZulu-Natal (KZN), Mpumalanga (MP) and Limpopo (LP), in 2006 and 2007. Aflatoxin levels of groundnut kernels were quantified using an ELISA technique. The occurrence of A. parasiticus colonies was predominant and it was isolated at twice the frequency of A. flavus. Aflatoxins were present in groundnut produced in the northern parts of KZN, where aflatoxin levels of up to 131 parts per billion (ppb) were found. In Mpumalanga and Limpopo, the highest aflatoxin levels were 160 ppb and 2 ppb, respectively. In the Makhanisi and Mbazwane localities situated in KwaZulu-Natal, and in Boshoffontein in Mpumalanga, aflatoxin levels were higher than the maximum permitted level set by the Food and Drug Administration in the USA (20 ppb), the European Union (6 ppb) and the Department of Health in South Africa (10 ppb) for groundnut that is intended for direct human consumption. This study indicates the need for mycotoxin awareness campaigns and control programs to be implemented in rural areas of South Africa

Aflatoxin and fumonisin on sorghum grain from commercial production areas of South Africa

Sorghum plays an important role in food security in Africa where it serves as the staple food for millions of people. The crop, however, is susceptible to infection by mycotoxigenic fungi such as Aspergillus flavus, A. parasiticus, Fusarium andiyazi, F. thapsinum, F. verticillioides and F. proliferatum. This can lead to a reduction in yield and the production of aflatoxin and fumonisin that are harmful to humans and animals. Sorghum grain samples were collected from five cultivars planted at 21 localities in South Africa from 2007-2009. Each sample was subjected to quantitative (q) real-time-PCR to determine the presence and biomass of aflatoxin-producing Aspergillus spp. and fumonisin-producing Fusarium spp. Aflatoxin and fumonisin amounts were also quantified by means of High Performance Liquid Chromatography (HPLC). HPLC results yielded minute amounts of aflatoxin with little or no fungal contamination determined with qPCR. The soft grain genotype NS5511 was more prone to aflatoxin contamination than the other cultivars. Fumonisin-producing Fusarium spp. were absent from sorghum samples collected in 2007. In 2008, sorghum samples from the Northwest and Kwa-Zulu Natal Provinces had small amounts of fungal contamination. In 2009, a low amount of fungi from samples from Northwest, Kwa-Zulu Natal and the Free State Provinces were recorded. Although small amounts of fungi were present, fumonisin were not produced. HPLC and qPCR results indicate that Aspergillus and Fusarium spp. and their mycotoxins do not pose a threat to sorghum production in South Africa

Resistance in maize inbred lines to Fusarium verticillioides and fumonisin accumulation in South Africa

Fusarium ear rot of maize, caused by Fusarium verticillioides, is an important disease affecting maize production worldwide. Apart from reducing yield and grain quality, F. verticillioides produces fumonisins which have been associated with mycotoxicoses of animals and humans. Currently, no maize breeding lines are known with resistance to F. verticillioides in South Africa. The objective of this study, therefore, was to evaluate 24 genetically diverse maize inbred lines as potential sources of resistance to Fusarium ear rot and fumonisin accumulation in field trials at Potchefstroom and Vaalharts in South Africa. After artificial silk channel inoculation with F. verticillioides, Fusarium ear rot development was determined at harvest and fumonisins B 1, B 2, and B 3 quantified. A significant inbred line by location effect was observed for Fusarium ear rot severity (P ≤ 0.001), although certain lines proved to be consistently resistant across both locations. The individual inbred lines also differed considerably in fumonisin accumulation between Potchefstroom and Vaalharts, with differentiation between susceptible and potentially resistant inbred lines only being possible at Vaalharts. A greenhouse inoculation trial was then also performed on a subset of potentially resistant and highly susceptible lines. The inbred lines CML 390, CML 444, CML 182, VO 617Y-2, and RO 549 W consistently showed a low Fusarium ear rot (<5%) incidence at both Potchefstroom and Vaalharts and in the greenhouse. Two of these inbred lines, CML 390 and CML 444, accumulated fumonisin levels <5 mg kg -1. These lines could potentially act as sources of resistance for use within a maize breeding program. © 2012 The American Phytopathological Society