A. Ortega-Beltran, L. Kaptoge, A.L. Senghor, M.O.S. Aikore, P. Jarju, H. Momanyi, M. Konlambigue, T.D.O. Falade, J. Atehnkeng, G. Mahuku, and R. Bandyopadhyay
Various biocontrol products under the Aflasafe trade name have been developed to address aflatoxin contamination in maize, groundnut, and sorghum in several African countries. The Aflasafe products contain four native atoxigenic Aspergillus flavus strains as the active ingredient.
The products are normally manufactured by coating sterile sorghum grains with a suspension of freshly produced spores of active ingredients mixed with a polymer and a dye. However, producing the active ingredient is somehow difficult and is the main limitation to manufacturing high-quality products. BAMTAARE, the Aflasafe licensee in Senegal, had difficulties producing the spores during its first year of operation because the laboratory to produce spores was not finished on time.
BAMTAARE had a large order from a major groundnut processor that planned to work with a farmer cooperative to produce aflatoxinsafe groundnut. There was the risk of failing to deliver the order. A process was developed in the lab in Ibadan for producing high‐ quality dry spores to overcome this.
In 2019, BAMTAARE manufactured Aflasafe SN01 using dry spores produced in Ibadan and sent via courier. BAMTAARE received 4kg of dry spores to manufacture 200 tons of Aflasafe to treat and protect 20,000 ha of commercially grown groundnut and maize in Senegal and The Gambia and for effectiveness trials in Mali (300 fields).
This much‐needed innovation was rapidly conceptualized, developed, tested, and validated in the laboratory and used industrially to produce a reliable aflatoxin mitigation tool in the field. Thousands of commercial farmers in Senegal and The Gambia had access to the technology as a part of an integrated aflatoxin management program that included pre‐ and postharvest interventions. Most farmers were able to produce aflatoxin-safe crops: less than 4 ppb (the tolerance threshold in the EU) compared to up to 380 ppb in untreated crops.
In December 2020, during the COVID-19 pandemic, the production of Aflasafe products with dry spores continued. Farmers in Tanzania, Mozambique, and Malawi needed Aflasafe products. The dry spores of the active ingredients for the three countries were shipped from Ibadan to the Aflasafe manufacturer in Tanzania (A to Z Textiles Ltd), who produced the products in record time. A to Z shipped the Mozambique and Malawi products to one company each in the two countries for distribution. Farmers received the Aflasafe products in time to treat their fields and are producing aflatoxin-safe groundnut. In addition, dry spores of atoxigenic strains to constitute the biocontrol products specific for Burundi and Uganda were sent to IITA Dar es Salam for manufacturing and to both countries for field effectiveness testing.
The dry spore innovation makes biocontrol manufacturing more versatile, cost‐efficient, and accessible to smallholder farmers in several African countries without compromising its effectiveness. Efforts to develop the innovation are part of ongoing actions to improve the archetype of the technology. The laboratory-scale process to dry the spores, however, needs improvement to make it more cost efficient. Currently, an industrial-scale version of the dry spore technology is being developed for scale-up.
More information on the process to produce the dry spore process and the effectiveness of Aflasafe manufactured with dry spores in commercially grown crops:
Fig. 1. A brief description of the process to dry spores of atoxigenic isolates of Aspergillus flavus. Harvesting fungal spores from colonized sorghum grains using sterile funnels with the stem covered with a sterile 1.7-mm2 sieve (A). Harvested fungal spores in suspension in a 250-ml glass bottle (B). Vacuum-dried fungal spores on Tyvek® membrane (lining the sieve in a Büchner funnel) being collected using a sterile spatula (C). Spore powder transferred to a sterile glass vial and ready for drying in the oven; note minimum humidity at the bottom of the vial (D).
Fig. 2. Manufacturing facility in Kahone, Senegal, where a seed treater (T) is used to coat roasted sorghum grains with a mixture of spore suspension, blue food colorant, and a polymer (A). Biocontrol product temporarily stored in a 1-ton bag and ready to be packaged in 5-kg plastic bags (B).
Fig. 3. Trials conducted in six regions in Senegal with conventional formulation in 2018 (A) and dry spore formulation in 2019 (B). The percentage of groundnut and maize crops in each of four total aflatoxin concentration categories is indicated by different colors. The outer circle shows Aflasafe SN01-treated crops, while the inner circle shows untreated crops. For groundnut, there were 150 and 120 farmer field trials in 2018 and 2019, respectively. For maize, there were 90 and 70 farmer field trials in 2018 and 2019, respectively. In all cases, half of the trials were treated and the rest untreated.