Mixture of traditional edible plants inhibits fungus growth in corn, study shows

UNIVERSITY PARK, Pa. — Fungal contamination in stored grain across sub-Saharan Africa causes major post-harvest loss and severe public health risks, costing billions of dollars annually, according to the Food and Agriculture Organization of the United Nations (FAO). High humidity, warm temperatures and inadequate storage facilities can drive mold proliferation and toxin production in staple crops like corn and the cereal grain sorghum.

Farmers in West Africa have long used a mixture of traditional plants to reduce fungi in grain storage, but the true impact of this approach was unknown, according to an international team led by Penn State food scientists. Now, that team has found that a formulation made from an evergreen tree called neem, lemongrass, garlic and hot chili plants effectively inhibits the growth of two kinds of Fursarium fungus in corn.

They recently published their findings in Access Microbiology.

“We wanted to see if those plants actually worked and if a combination would be more effective,” said team leader and study senior author Josephine Wee, associate professor of food science in the College of Agricultural Sciences. “In sub-Saharan Africa, there are many, many smallholder farmers who grow small lots of grains, and they store their harvest. Then it gets collected and stored again before it reaches the facility that actually processes it. The warm, humid climate induces the growth of mold, which ruins the harvest, leading to decreased income for the farmers and decreased food supply for the community. Increases in global temperatures might make this problem worse.”

Study co-first author Elisee Kouassi Kporou, a researcher with Université Jean LOROUGNON GUÉDÉ, Côte d’Ivoire, or Ivory Coast, was a Fulbright scholar in Wee’s lab in the Penn State Department of Food Science when the research was conducted. He led the team that developed BioCC+ in Côte d’Ivoire — made with edible plants used by farmers and their ancestors to protect their grain — and then evaluated its antifungal potential at Penn State.

The team evaluated BioCC+’s ability to protect against two fungal species that commonly infect corn and produce mold toxins that sicken people and livestock: Fusarium graminearum and Fusarium verticillioides. The researchers prepared extracts from BioCC+ and tested whether the extracts stopped fungal growth. Then they separated the extract into smaller chemical fractions and tested each fraction again, determining which had more antifungal activity.

The researchers compared extracts made with water, methanol and dichloromethane — a clear, volatile liquid widely used in industrial and laboratory settings because it can dissolve a vast array of organic compounds. They found that the dichloromethane extract was the most effective antifungal preparation.

The team found that the BioCC+ extracts inhibited fungal growth, and the minimum concentrations required were 12.5 milligrams of BioCC+ extract per milliliter of dicholoromethane against Fusarium graminearum and 25 milligrams of BioCC+ extract per milliliter of dicholoromethane against Fusarium verticillioides.

In total, the researchers identified six possible active compounds likely responsible for the observed antifungal effects — two previously known compounds and four compounds that have not yet been characterized.

“BioCC+ was developed from traditional plant-based practices in Côte d’Ivoire, and this collaboration allowed us to scientifically evaluate and better understand its potential,” Kporou said. “Our findings show how combining traditional knowledge with modern analytical and microbiological approaches can contribute to developing affordable, locally produced solutions to reduce fungal contamination and mycotoxin risks in stored corn.”

Wee is affiliated with the One Health Microbiome Center in the Huck Institutes of the Life Sciences at Penn State. She noted that the Huck Institutes’ Metabolomics Core Facility provided liquid chromatography–mass spectrometry support for the research. She also acknowledged the contributions of researchers and farmers affiliated with Université Jean LOROUGNON GUEDE, Côte d’Ivoire, for conducting preliminary studies and initial field studies with BioCC+.

Zilfa Irakoze, dual title doctoral student in food science and international agriculture and development at Penn State, was co-first author on the study.

Contributing to the research at Penn State were Joshua Lambert, professor of food science; Joshua Kellogg, associate professor in the Department of Veterinary and Biomedical Sciences; and Nataliia Voloshchuk, postdoctoral scholar in the Department of Food Science.

This work is supported by the U.S. Department of Agriculture’s National Institute of Food and Agriculture and Hatch Appropriations under project numbers PEN04991, PEN05008 and PEN04956, and under accession numbers 7007024, 7007470 and 7006496. Elisee Kouassi Kporou was supported by the Fulbright Visiting Scholar program through a Fulbright Scholar Award. This content is solely the responsibility of the authors and does not necessarily represent the views of the funders.