en عمومى General پژوهشي Research <strong>Background:</strong> Aflatoxin B1 (AFB1) is a mutagenic and carcinogenic compound mainly produced by the <em>Aspergillus parasiticus</em>, <em>A. flavus</em>, <em>A. nomius</em>, <em>A. tamari</em>, and <em>A. pseudotamarii</em>. AFB1 biodegradation is the most important strategy for reducing AFB1 in plant tissues. Bacteria can deactivate and biodegrade AFB1 for effective detoxification of contaminated products. The present study investigated the efficiency of AFB1 degradation by soil bacteria from the Southern Khorasan Province in Eastern Iran by thin-layer and high-performance liquid chromatography during 2014&ndash;2015.<br> <strong>Methods:</strong> DNA was extracted from AFB1-degrading isolates by the cetyltrimethylammonium bromide method and the 16S rRNA gene was amplified with the 27f and 1492r general bacterial primers and the sequences were used to identify the isolates based on their similarity to Gene Bank sequences of known bacterial species.<br> <strong>Results:</strong> We isolated five strains from four species of AFB1-degrading bacteria from Birjand plain, including <em>Bacillus pumilus</em>, two isolates of <em>Ochrobactrum pseudogrigonens</em>, <em>Pseudomonas aeruginosa</em>, and <em>Enterobacter cloace</em>, which had AFB1-degrading activities of 88%, 78%, 61%, 58%, and 51%, respectively.<br> <strong>Conclusion:</strong> We provide the first demonstration of AFB1 degradation by <em>B. pumilus</em> in from Iran and the first report identifying <em>O. pseudogrigonens </em>and <em>E. cloace</em> species as having AFB1-degrading activity. Degrading, Detoxification, Enterobacter cloace, Ochrobactrum pseudogrigonens, Pseudomonas aeruginosa 39 44 http://ijt.arakmu.ac.ir/browse.php?a_code=A-10-507-1&slc_lang=en&sid=1 Fahimeh Sangi 100319475328460011236 100319475328460011236 No MS student of Plant Pathology, College of Agriculture, University of Birjand, Birjand, Iran. Abbas Mohammadi amohammadi@birjand.ac.ir 100319475328460011237 100319475328460011237 Yes Department of Plant Pathology, College of Agriculture, University of Birjand, Birjand, Iran. Nazar Afzali 100319475328460011238 100319475328460011238 No Department of Animal Science, College of Agriculture, University of Birjand, Birjand, Iran. Mansoureh Mirabolfathy 100319475328460011239 100319475328460011239 No PhD of Mycology, Mycotoxins Research Laboratory, Iranian Research Institute of Plant Protection, Tehran, Iran.