The occurrence of toxigenic moulds in traditional household morogo of Giyani

Abstract

An estimated 57 % of the black Africans in South Africa live in rural areas. Traditional vegetables play an important role in providing nutrition for rural subsistence households. Morogo refers to traditional leafy vegetables that are well adapted to local growing conditions, produce high yields and can be cultivated cost-effectively. Some of these vegetables occur as weedy plants in cultivated lands. The dietary value and cultivation practices of traditional vegetables are largely embedded in indigenous knowledge systems of local communities and not well documented in scientific literature. The present study was conducted in a rural African community in the Mopani District of the Limpopo Province. Questionnaires were used to obtain and document information related to morogo types consumed, subsistence agricultural practices as well as traditional food preservation and processing methods. Since dietary safety of food produced for rural household subsistence has - received little attention, the mycological safety of morogo was investigated. Standard techniques were employed to isolate potential toxigenic fungi from fresh and processed household morogo. Members of the fungal genera Aspergillus and Penicillium were present in low numbers. Alternaria was isolated in relatively high numbers mainly from internal leaf structures and Fusarium strains from leaf surfaces. Fusarium levels were found to be lower in samples of sun-dried, cooked and rinsed morogo. Molecular techniques were employed to confirm the identity of suspected fumonigenic Fusarium isolates and the presence of fumonisin-encoding genes. Fumonisin-producing Fusarium in the subsistence agro environment implies a risk that morogo might be contaminated with fumonisin mycotoxins. Subsequent research should be aimed at investigating the source of Fusarium contamination in the subsistence agro-environment and identifying risk factors for toxin production in traditional morogo.