Abstract B24: Biological approaches for reducing fumonisin carcinogens in maize
Authors: Alberts Johanna Francina , Zyl Willem Heber Van , Gelderblom Wentzel Christoffel 
Published: December 2017

Control methods to reduce exposure to the fumonisin carcinogens in maize are critical, especially in rural subsistence populations at an increased risk. The fumonisins are a group of mycotoxins mainly produced by Fusarium spp. They are hepatocarcinogenic to rodents, and have been associated with oesophageal and liver cancer in subsistence maize farming communities around the world. The intact molecule and the free amino group determine the cancer-initiating activity, while the carballylic acid moiety plays an active role in absorption of the fumonisins from the gut. Fumonisin B1 (FB1) is the most abundant naturally occurring fumonisin on maize and maize-based food worldwide and is classified as a Group 2B carcinogen by the International Agency for Research on Cancer (IARC). The Joint FAO/WHO Expert Committee on Food Additives (JECFA) has determined a group provisional maximum tolerable daily intake (PMTDI) for FB1, FB2, and FB3, alone or in combination, of 2 µg/kg body weight/day. In many Sub-Saharan countries, where both maize contamination and maize consumption are high, regulatory mechanisms to control mycotoxin levels, including fumonisin, are either lacking or are not enforced. Therefore, reducing exposure levels by interventions, specifically those based on simple low-cost measures acceptable to these communities, becomes relevant.

Although certain physical and chemical methods for control of Fusarium diseases and the fumonsins in maize are currently applied, there are several concerns with regards to the health, safety and environmental risks. Biologically based methods are increasingly being explored, including several approaches pre-harvest (breeding for resistant maize cultivars; introduction of biocontrol microorganisms; application of phenolic plant extracts; expression of antifungal proteins and fumonisin degrading enzymes in transgenic maize cultivars). Postharvest approaches include removal of fumonisins from food by natural clay adsorbents and enzymatic degradation of fumonisins through decarboxylation and deamination by recombinant carboxylesterase and aminotransferase enzymes.

This paper will discuss biologically based control methods with special emphasis on the development of food-grade recombinant enzymes and its possible application during the conditioning stage of commercial dry milling of maize. Cultural specific and simple intervention strategies for introduction of these methods to rural communities at risk will also be discussed. Biologically based approaches could be beneficial as control measure to reduce exposure of populations exposed to high levels of this carcinogen.

Citation Format: Johanna Francina Alberts, Willem Heber Van Zyl, Wentzel Christoffel Gelderblom. Biological approaches for reducing fumonisin carcinogens in maize [abstract]. In: Proceedings of the AACR International Conference: New Frontiers in Cancer Research; 2017 Jan 18-22; Cape Town, South Africa. Philadelphia (PA): AACR; Cancer Res 2017;77(22 Suppl):Abstract nr B24.