A multidisciplinary cooperation project between German and African research institutions
A fungal toxin that is one of the most toxic natural substances is the subject of the international AflaZ cooperation project: Aflatoxin. The research work ranges from the infestation of maize plants in the field by aflatoxin-forming fungi, to insects that spread the fungal spores, to cow's milk in which toxic derivatives of aflatoxin are found. A project result of the Department for Safety and Quality of Fruit and Vegetables, which is also coordinating the project, is that aflatoxin M1, a metabolic product of aflatoxin, is also formed by the fungus itself on corn and is therefore not only found in milk, as is often assumed. Studies of the genome confirm the fungus' ability to produce aflatoxin M1. Since the fungus in food is not always visible to the naked eye, a molecular monitoring system based on a new and very accurate technique, droplet digital PCR, has also been developed.
Africa, continent of adventure and danger - that's how people commonly imagine Africa. But the dangers are not always obvious: the warm, humid climate provides optimal growth conditions for molds such as Aspergillus flavus and can lead to a high level of contamination of food and feed with the highly carcinogenic mold toxin aflatoxin. Aflatoxin is also regularly the cause of deaths, especially in children, the elderly and weakened people.
AflaZ, which stands for "Zero Aflatoxin", is a research project of the Max Rubner-Institut (MRI), funded with around 1.5 million euros, in which strategies are being developed to reduce the aflatoxin contamination of foods frequently consumed in Kenya. Together with scientists from the Friedrich Loeffler Institut (FLI), the Julius Kühn Institut (JKI), the University of Koblenz-Landau (UKL), and two project partners in Kenya, KALRO (Kenya Agricultural and Livestock Research Organization) and EAFF (Eastern African Farmers Federation), the formation of aflatoxin on maize and the contamination of milk resulting from the ingestion of contaminated feed maize are being studied. Both foods are popular and widely consumed in sub-Saharan Africa. The project is coordinated by PD Dr. Markus Schmidt-Heydt, Department of Safety and Quality of Fruit and Vegetables of the MRI at the Karlsruhe site; two other MRI institutes at the Detmold and Kiel sites are also involved.
With this complex problem, only an approach that considers the overall context can lead to success: It is now known that not only is the protection of the plant from fungal attack important, but also the soil in which the plant grows has a major influence on mold infestation. Insects also play an important role in the formation of the dangerous mycotoxin: on the one hand by injuring the plant and thus creating entry points for the fungal infestation, and on the other hand as carriers of fungal spores. Optimization of processing and storage conditions requires comprehensive chemical and molecular biological analyses of both the plant and the fungus for the presence and formation of aflatoxin. If infested maize cobs are fed to dairy cows, transfer of the toxin into cow's milk can occur, known as "carry over." The investigations are addressing all of these points.
During the project period, important scientific successes have already been achieved by the project partners involved. Among other things, the Department for Safety and Quality in Fruit and Vegetables was able to show that aflatoxin M1, a metabolic product of aflatoxin, is also formed by the fungus on maize and is therefore not only present in milk, as is often assumed. Studies of the genome confirm the fungus' ability to produce aflatoxin M1. Since the fungus in food is not always visible to the naked eye, a molecular monitoring system based on a new and very accurate technique, droplet digital PCR, has been developed. In addition, laboratory experiments demonstrated the efficacy of the mycoparasitic fungus Trichoderma afroharzianum as a biocontrol organism against plant pathogenic and mycotoxin-producing fungi. Other project partners demonstrated the antifungal effect of various companion plants such as Lippia adoensis and Ocimum gratissimum on aflatoxin-forming fungi, or provide on-site support to Kenyan farmers involved in the project throughout its duration. Regular training courses are held in Kenya on the project findings on maize cultivation, harvesting and crop storage, are already leading to reduced aflatoxin contamination and thus increased food safety for the Kenyan population. For example, numerous farmers were able to improve their method of determining the degree of dryness of their maize crop in order to minimize infestation by fungi. The application of good agricultural practices has also increased yields.
In 2022, an AflaZ TV documentary will be aired on television channels in Kenya to share the work and findings of all AflaZ project partners. Especially for small, rural farms, some with centuries-old farming traditions, it is often difficult to achieve changes in management. Communication adapted to the conditions and partnership-based cooperation between scientists and farmers are important prerequisites for sustainable knowledge transfer, cultural acceptance of the recommendations and the adoption of the new methods and the acquired knowledge by the local population.
And: Due to climate change, the fungus Aspergillus flavus is now increasingly detected in southern European countries, contamination of food with aflatoxins will therefore also increase in Germany.