title: Novel Aflatoxin-Degrading Enzyme from Bacillus shackletonii L7.
abstract: Food and feed contamination by aflatoxin (AF)B₁ has adverse economic and health consequences. AFB₁ degradation by microorganisms or microbial enzymes provides a promising preventive measure. To this end, the present study tested 43 bacterial isolates collected from maize, rice, and soil samples for AFB₁-reducing activity. The higher activity was detected in isolate L7, which was identified asBacillus shackletonii. L7 reduced AFB₁, AFB₂, and AFM₁ levels by 92.1%, 84.1%, and 90.4%, respectively, after 72 h at 37 °C. The L7 culture supernatant degraded more AFB₁ than viable cells and cell extracts; and the degradation activity was reduced from 77.9% to 15.3% in the presence of proteinase K and sodium dodecyl sulphate. A thermostable enzyme purified from the boiled supernatant was designated as Bacillus aflatoxin-degrading enzyme (BADE). An overall 9.55-fold purification of BADE with a recovery of 39.92% and an activity of 3.85 × 10³ U·mg-1was obtained using chromatography on DEAE-Sepharose. BADE had an estimated molecular mass of 22 kDa and exhibited the highest activity at 70 °C and pH 8.0, which was enhanced by Cu2+and inhibited by Zn2+, Mn2+, Mg2+, and Li⁺. BADE is the major protein involved in AFB₁ detoxification. This is the first report of a BADE isolated fromB. shackletonii, which has potential applications in the detoxification of aflatoxins during food and feed processing.
authors.affiliation: Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, 1 Nongda South Road, Xibeiwang Town, Haidian District, Beijing 100193, China. xuliang19824@163.com.|Key Laboratory of Agro-products Processing, Ministry of Agriculture, 1 Nongda South Road, Xibeiwang Town, Haidian District, Beijing 100193, China. xuliang19824@163.com.
authors.forename: Liang
authors.initials: L
authors.lastname: Xu
authors.affiliation: Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, 1 Nongda South Road, Xibeiwang Town, Haidian District, Beijing 100193, China. elfarahy89@hotmail.com.
authors.forename: Mohamed Farah
authors.initials: MF
authors.lastname: Eisa Ahmed
authors.affiliation: Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, 1 Nongda South Road, Xibeiwang Town, Haidian District, Beijing 100193, China. lancin.sangar@gmail.com.
authors.forename: Lancine
authors.initials: L
authors.lastname: Sangare
authors.affiliation: Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, 1 Nongda South Road, Xibeiwang Town, Haidian District, Beijing 100193, China. zhaoyueju@caas.cn.|Key Laboratory of Agro-products Processing, Ministry of Agriculture, 1 Nongda South Road, Xibeiwang Town, Haidian District, Beijing 100193, China. zhaoyueju@caas.cn.
authors.forename: Yueju
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, 1 Nongda South Road, Xibeiwang Town, Haidian District, Beijing 100193, China. sjonnim@gmail.com.
authors.forename: Jonathan Nimal
authors.initials: JN
authors.lastname: Selvaraj
authors.affiliation: Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, 1 Nongda South Road, Xibeiwang Town, Haidian District, Beijing 100193, China. xingfuguo@caas.cn.|Key Laboratory of Agro-products Processing, Ministry of Agriculture, 1 Nongda South Road, Xibeiwang Town, Haidian District, Beijing 100193, China. xingfuguo@caas.cn.
authors.forename: Fuguo
authors.initials: F
authors.lastname: Xing
authors.affiliation: Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, 1 Nongda South Road, Xibeiwang Town, Haidian District, Beijing 100193, China. awangyan@126.com.|Key Laboratory of Agro-products Processing, Ministry of Agriculture, 1 Nongda South Road, Xibeiwang Town, Haidian District, Beijing 100193, China. awangyan@126.com.
authors.forename: Yan
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Shenyang Institute of Engineering, No.18 Puchang Road, Shenbei New District, Shenyang 110136, China. yanghp@sie.edu.cn.
authors.forename: Hongping
authors.initials: H
authors.lastname: Yang
authors.affiliation: Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, 1 Nongda South Road, Xibeiwang Town, Haidian District, Beijing 100193, China. liuyang01@caas.cn.|Key Laboratory of Agro-products Processing, Ministry of Agriculture, 1 Nongda South Road, Xibeiwang Town, Haidian District, Beijing 100193, China. liuyang01@caas.cn.
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
mesh_terms: D016604:Aflatoxin B1 / Q000378:metabolism*; D016607:Aflatoxin M1 / Q000378:metabolism*; D000348:Aflatoxins / Q000378:metabolism*; D001407:Bacillus / Q000145:classification / Q000201:enzymology*; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D008658:Inactivation, Metabolic; D008670:Metals / Q000737:chemistry; D013379:Substrate Specificity; D013696:Temperature; D013997:Time Factors
chemical_list: D000348:Aflatoxins; D001426:Bacterial Proteins; D008670:Metals; D016607:Aflatoxin M1; C029753:aflatoxin B2; D016604:Aflatoxin B1
keywords: Bacillus shackletonii; aflatoxin B1; aflatoxin-degrading enzyme; biodegradation; purification