Aflatoxin B1 is a naturally occurring mycotoxin that is produced as secondary metabolite by Aspergillus spp., especially A. flavus and A. parasiticus. This is the most severe toxin due to its carcinogenic, mutagenic, and teratogenic properties. Hence, methods for toxin degradation have been received increasing interest from both scientific communities and industries. In this study, 32 isolates of Bacillus spp. from various fermented cereal products were screened for their aflatoxin B1 degradation ability. The results indicated the extracellular fraction of Bacillus subtilis BCC 42005 isolated from Iru (African locust bean) potentially possessed aflatoxin B1-degrading ability. The maximum activity of the active fraction was at 50°C and pH 8.0. The activity was stable in a wide range of pH (5.0-8.0) and temperature (25-60°C). The aflatoxin B1-degrading mechanisms of this strain may be possibly involved by enzyme(s). This extracellular fraction was not toxic at IC50 4 mg/ml and it can be combined with water as a soaking agent for maize, which results in 54% of aflatoxin B1 reduction after contact time 120 min. Hence, the extracellular fraction of Bacillus subtilis BCC 42005 can be further applied as an effective soaking agent in a pretreatment process with a practical and easy-to-implement condition and also probably used to reduce the aflatoxin B1 contamination in other foods and feeds commodities.
Keywords: Bacillus subtilis; Aflatoxin B1; aflatoxin B1-degrading enzyme; biodegradation.