Native to the savannas of western and central Africa, the locust bean (néré) tree is a highly prized natural resource. Locust bean seeds produced by these trees are an important, nutrient-rich food source for people from Senegal to Uganda (1).
Locust bean pods, containing both edible pulp and seeds, are highly nutritious. The pulp is sweet (carbohydrate-rich) and can be consumed directly from the plant; the seeds are even more valuable, as a concentrated source of protein, fat, calcium and B vitamins but are usually eaten in fermented form (2,3).
Locust bean seeds are prepared for consumption by boiling and fermenting (wrapped in leaves providing Bacillus subtilis and other bacterial species) into a popular food known most commonly as dawadawa (in Hausa-based languages of Ghana, Cameroon, Cote d'Ivoire,Togo, Benin & Niger)(5). Like natto, fermented dawadawa has a pungent odor and is used (like Korean doenjang) as a condiment or stew ingredient (5).
In other African languages/countries, dawadawa has many alternative names: iru (Yoruba), sambala (Mandig/Burkina Faso), oji (Pulaar), kinda (Sierra Leone) or netetou (Wolof) (4).
What does all this have to do with natto? In many areas, dawadawa is increasingly being made from soybeans. Soybeans are replacing néré seeds in traditional dawadawa because of shortages in locust beans along with mounting cultivation of soybeans in Africa (5,6). Naturally, soy-based preparation of dawadawa results in a food even more similar in composition and microbiology to natto than the traditional locust bean-based version (3,5).
How amazing that such diverse and distant cultures discovered independently that fermenting cooked soy (and other legumes) with leaf-borne Bacillus subtilis (and other bacteria) produces a pungently delicious and highly nutritious food!
References: (1) http://blogs.worldwatch.org/nourishingtheplanet/the-locust-bean-an-answer-to-africa’s-greatest-needs-in-one-tree/ (2) Wikipedia [Parkia biglobosa]:http://en.wikipedia.org/wiki/Parkia_biglobosa (3) Ray, R.C. and Montet, D. (2015) Microorganisms and Fermentation of Traditional Foods. CRC Press. (4) Wikipedia [Sumbala]: http://en.wikipedia.org/wiki/Sumbala (5) Tamang, J.P. and Kailasapathy.(2010) Fermented Foods and Beverages of the World. CRC Press. (6) http://foramfera.com/index.php/market-research-reports/item/652-soy-dawadawa-production-from-soya-beans-seed-the-feasibility-report