The 15 th FOOD INNOVATION ASIA CONFERENCE 2013 13 th -14 th June 2013 BITEC Bangna, Bangkok, Thailand Localization and Characterization of Aflatoxin B 1 -degrading Activity 1 of Bacillus subtilis IRU-1A 2 1 Namon Watanakij, 1 Awanwee Petchkongkaew and 2 Wonnop Visessanguan* 3 1 Department of Food Science and Technology, Faculty of Science and Technology, 4 Thammasat University (Rangsit Campus), Pathum Thani, 12120. Thailand. 5 2 National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology 6 Development Agency (NSTDA), 113 Thailand Science Park, Pathum Thani, 12120. Thailand. 7 * Corresponding author: wonnop@biotec.or.th 8 9 Abstract 10 Aflatoxin B 1 is a naturally occurring mycotoxin that is produced as secondary 11 metabolite by Aspergillus spp., especially A. flavus and A. parasiticus. This toxin is the most 12 severe toxin due to its carcinogenic, mutagenic and teratogenic properties. Hence, methods 13 for toxin detoxification/degradation have been received increasing interest from both 14 scientific communities and industries. From our previous study, Bacillus subtilis IRU-1A, 15 isolated from Iru, a Nigerian fermented locust beans, was found to possess aflatoxin B 1 - 16 degrading ability. Therefore, the aim of this study was to study the cellular location of 17 aflatoxin B 1 -degrading activity and characteristics of enzyme possibly involved. The 18 extracellular, intracellular and membrane-associated fractions were studied for aflatoxin B 1 - 19 degrading activity. The result indicated that the aflatoxin B 1 -degrading activity of Bacillus 20 subtilis IRU-1A located in the extracellular fraction. The maximum activity was at 50 °C and 21 pH 8.0. The activity was stable in a wide range of pH (5.0-8.0) and temperature (25-60 °C). 22 Thus, the extracellular fraction of Bacillus subtilis IRU-1A can be probably used to reduce 23 the aflatoxin B 1 contamination in some foods and feeds commodities. 24 Keywords: Aflatoxin B 1 , Biodegradation, Bacillus subtilis, Extracellular fraction 25 Introduction 26 Aflatoxins are naturally occurring mycotoxins that are produced as secondary 27 metabolites by filamentous fungi, especially Aspergillus flavus and A. parasiticus (Pitt 2000). 28 These toxins mainly contaminate in agricultural products such as maize, sorghum, rice, 29 wheat, spices, oil seeds and nuts and they cause aflatoxicosis in humans and animals. Among 30 these, Aflatoxin B 1 is the most hazardous and severe toxin due to its metabolism that can be 31 changed into exo-AFB1-8,9-epoxide (AFBO), which binds to DNA and other critical cellular 32 macromolecules, and results in hepatocellular carcinoma (Rawal and others 2010). Moreover, 33 International Agency for Research on Cancer classified this toxin as a group I of human 34 carcinogen (IARC 1993). 35