https://www.frontiersin.org/articles/10.3389/fmicb.2019.02069/full

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Response from Fen Beed, IITA Tanzania focusing on bicontrol of aflatoxin in East Africa – [email protected] under leadership of Ranajit Bandyopadhay of IITA [email protected] leading aflatoxin management across Afica

In brief – see http://www.aflasafe.com/

Isolates of A. flavus are selected for biocontrol based on following characteristics

• Atoxigenic (shown through biochemical and molecular analyses)

• Ecologically competitive

• Unable to mate with toxin producing forms as shown through genetic profiling (SSR) and VCG (Vegetative Compatibility Grouping) analyses (i.e. VCG does not contain any toxigenic members)

Background: an innovative scientific solution in the form of biocontrol has been developed and commercialized by the United States Department of Agriculture – Agricultural Research Service (USDA-ARS), and is widely used in the Southern USA to combat aflatoxin contamination in maize, cotton and groundnut and more recently in pistachios. This breakthrough technology reduces aflatoxins during both crop development and post-harvest storage, and throughout the value chain. Naturally occurring atoxigenic strains are released to out-compete their aflatoxin-producing cousins. The innovative competitive exclusion technology carries over through the value chain, discouraging contamination in storage and transport even when conditions favor fungal growth. Aflatoxin producing fungi are present with crops in the field during crop development. These fungi can stay with crops during harvest, transport, and storage, until use. If the environment where crops are stored is humid and warm, the fungi, which moved into storage with the crop, can develop and contaminate the crop with aflatoxins. In the same manner, use of atoxigenic strains to competitively exclude aflatoxin-producers in the field provides significant carry-over benefits in storage. First, because there are fewer aflatoxin-producer fungal biotypes moving into storage and second, because the atoxigenic strain biocontrol agents stay with the crop until use and continue to protect against contamination after harvest. Thus, competitive exclusion in the field translates into decreased risk of aflatoxin contamination in storage and transport.

Positive influences of atoxigenic strain applications carry-over between crops and provide multi-year benefits. A single application of atoxigenic strains may benefit not only the treated crop but also rotation crops and second season crops that miss a treatment due to weather or grower error. Also, because fungi move across fields and throughout the environment, as the safety of fungal communities within treated fields improves, so does the safety of fungal communities in areas neighboring treated fields.

The International Institute of Tropical Agriculture (IITA), in partnership with USDA-ARS, the African Agricultural Technology Foundation (AATF), Doreo Partners and others, have successfully adapted this technology for use in Nigeria, Senegal and Burkina Faso on maize and groundnuts and on maize in Kenya. Native strains have been developed into a biocontrol product called Aflasafe. Ongoing field testing of Aflasafe on maize and groundnut in Nigeria over the past four years has produced very positive results in reducing aflatoxin contamination, consistently by 80-90%. The product consists of atoxigenic strains that are coated on sterile sorghum grains that act as a carrier and food source for the strains to proliferate for out-competing the toxigenic strains.

Development of Aflasafe is also currently underway or in the process of initiation in Eastern Africa (Kenya and Tanzania) and Southern Africa (Mozambique and Zambia) by IITA, USDA-ARS, AATF and national program partners with funding from various donors as follows:

 Kenya: Biocontrol product development funded by USDA, Bill & Melinda Gates Foundation and AATF,

 Tanzania: Mycotoxin prevalence analysis and biocontrol product development funded by USAID (Africa Rising) and PACA,

 Zambia: Aflatoxin prevalence analysis and biocontrol product development funded by the USAID-Zambia mission through the Feed-the-Future (FtF) initiative,

 Mozambique: Aflatoxin prevalence analysis and biocontrol product development funded by USDA, USAID and Government of Mozambique (approved; fund transfer being negotiated).

While most of the efforts are country-specific, there are commonalities in approach and methodologies in the work in various countries making them amenable to a regional initiative. In fact, biocontrol development funded by PACA aims to develop regional biocontrol strains that are endemic throughout the region. The rationale for developing a regional program is derived in essence by the aflatoxin problem itself. Aspergillus flavus reside in soil within agricultural environments and are dispersed by air to large distances; they do not recognize political borders and they exert influence across agro-ecosystems. Indeed many of the same toxic and atoxigenic strains of A. flavus found in one country are also found in neighboring countries sharing the same agro-ecosystem. Thus it makes sense to develop biocontrol products that can be used to address contamination in whole agro-ecosystems across counties. Availability of crop samples from each country is a prerequisite for the identification of regional biocontrol strains.

Cheers

Fen

Very interesting! thank you for sharing

It is pleasing that good work is  in progress. Thanks for sharing. I wish this could be combined with host plant resistance to aflatoxin producing fungi, field insect pests that damage plants, and storage pests that attack grain, improvement of grain storage facilities, development of supportive national policies and regulations so as to reduce further the levels of mycotoxins in staple foods plus increasing awareness among the consumers

In fact, a survey of Bangladeshi markets found a high incidence of aflatoxin in corn (Bhuiyan et al., 2013). Subsequent research revealed that, globally, South Asia had the highest incidence of aflatoxin contamination (82%) with 41% of the maize samples exceeding the most lenient EU standards for aflatoxin in feed (Gruber-Dorninger et al. 2019). The true extent of the cost to human health will never been known, but Turna and Wu (2019) calculated aflatoxin exposure in Bangladesh causes about 1311 new cases of liver cancer annually. A study of at-risk children in Dhaka, Bangladesh found 62% of 3-years old had aflatoxin biomarkers in blood plasma indicating chronic aflatoxin exposure (Mahfuz et al., 2019).

So we just start to identify native atoxigenic A. flavus to reduceaflatoxins contamination in maize.