The use of bacteria promises to be an innovative solution to reduce cadmium in cocoa plants. This heavy metal, although naturally found in soils, can be harmful to health if absorbed by plants like cocoa and reaches consumers.
Bacteria to prevent cadmium in cocoa
Currently, the presence of cadmium in agricultural products is strictly regulated under the parameters of the World Health Organization. Recent research indicates that certain bacteria could prevent this metal from penetrating plants. Discovered in Germany in 1817, cadmium is absorbed through plant roots, reaching cocoa almonds, which could increase the risk of diseases such as lung, liver, or kidney cancer in humans.
Concern in the global cocoa sector, especially in Colombia, is growing. In 2021, this country produced 69,000 tons of cocoa, but the presence of cadmium is a barrier to accessing demanding international markets, such as the European one.
Researcher Feria undertook a study in San Vicente de Chucurí, Santander, an area known for its high cocoa productivity and volcanic soils. His goal was to identify native bacterial genera that showed tolerance to cadmium. Sampling and analysis were conducted on eight farms, selecting four based on pH levels and cadmium concentration.
On each farm, the physicochemical properties of the soil were evaluated, and microbiological analyses were conducted to isolate and characterize bacteria. Twelve bacterial genera were identified with significantly high cadmium tolerance, up to 20 parts per million, while soil in Santander presents 1.2 to 1.6 parts per million.
These bacteria interact with cadmium in three main ways: bioabsorption, bioaccumulation, and biotransformation. In particular, the genus Klebsiella sp. showed effectiveness in transforming cadmium into forms not absorbable by the plant, such as cadmium carbonate.
In addition to mitigating cadmium absorption, the use of bacteria can complement sustainable agricultural practices, improving soil quality. This research, in collaboration with professors from the Faculty of Sciences of UNAL Medellín Campus and the National Chocolate Company, underscores the importance of public-private partnerships in advancing towards safer cocoa.
