Aflatoxin B₁-degrading activity from Bacillus subtilis BCC 42005 isolated from fermented cereal products

ABSTRACT

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:

• Aflatoxin B₁
• biodegradation
• Bacillus subtilis
• aflatoxin B₁-degrading enzyme

Acknowledgments

The authors would like to thank The Thailand Graduate Institute of Science and Technology (TGIST), Grant Number TGIST 01-53-032, for financial support. This work also received partial financial support from Thammasat University (grant number TN3/2553) and the Higher Education Research Promotion and National Research University Project of Thailand, Office of Higher Education Commission. Acknowledgements are also given to Center of Excellence in Food Science and Innovation, Faculty of Science and Technology, Thammasat University and National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA) for providing laboratory equipments and facilities.

Additional information

Funding

This work was financially supported by the Thailand Graduate Institute of Science and Technology (TGIST) under Grant number [TGIST 01-53-032]; the TU Research Scholar under Grant number. [TN3/2553]; and the Higher Education Research Promotion and National Research University Project of Thailand, Office of Higher Education Commission.