Use of Theobroma cacao Pod Husk-Derived Biofertilizer is Safe as it Poses neither Ecological nor Human Health Risks

Abstract

Cacao farmers use macerated Theobroma cacao pod husks as biofertilizer for restoration of environmentally important soil elements, i.e., N, P, K, Na, Mg, and Ca. The increasing popularity of this organic material for soil management justifies to experimentally ascertaining that its application does not produce environmental or human health risks. We therefore applied a battery of biological tests to assess possible health risks related to the extract of fermented cacao pod husks [CHE]. Minimal inhibitory concentration for selected bacteria and fungi was established and an antiviral assay (equine herpes virus – EHV-1) and insecticide assay (Aedes aegypti larvae), to observe possible environmental impact. Toxicity tests used Artemia salina, hemolytic activity and cytotoxicity were tested using HT-29 e Vero cells, respectively. Genotoxicity and anti-genotoxic activity was tested in the comet assay of leukocytes and a selection of Saccharomyces cerevisiae mutants allowed look for a possible interference of CHE with defined metabolic pathways. None of these established tests used to define toxicity and genotoxicity of chemical compounds indicated that CHE contained substances that would pose such risks. Our safety assessment on bacteria and yeasts, virus, insect larvae, and human leukocytes [3-(4,5-di-methylazol-2- yl)-2,5- diphenyltetrazolium bromide (MTT) and comet assay] thus indicated that macerated cocoa pod husk can be safely used as biofertilizer.