D'Souza D H, Brackett R E
Center for Food Safety and Quality Enhancement, Department of Food Science and Technology, The University of Georgia, Griffin 30223-1797, USA.
J Food Prot. 1998 Dec;61(12):1666-9. doi: 10.4315/0362-028x-61.12.1666.
Flavobacterium aurantiacum NRRL B-184 possesses the ability to degrade aflatoxin B1 in solution and in several food items. Aflatoxin B1 is a potent carcinogen that causes significant economic losses to the agricultural and food industry. The role of trace metal ions (Cu2+, Mn2+, Zn2+, and Co2+) were studied in an effort to understand the enzymatic system involved in aflatoxin B1 degradation by F aurantiacum. The effect of divalent chelators (EDTA and 1,10-phenanthroline [OPT]) in the presence of the trace metal ions was studied as well. Aflatoxin B1 (10 microg/ml) was added to 72-h cultures of F aurantiacum that had been washed and resuspended in phosphate buffer (pH 7.0). HPLC was used to determine aflatoxin B1 concentration in these cultures. Incubating cells at 30 degrees C with 1 and 10 mM Cu2+, Mn2+, and Zn2+ significantly decreased aflatoxin B degradation after 4 and 24 h (P < 0.05). Decreased degradation was also observed with 1 and 10 mM Cu2+ and Zn2+ after 48 h and with 0.1 mM Cu2+ after 24 and 48 h. Co2+ did not have a significant effect on aflatoxin B1 degradation. EDTA and OPT did not counter the inhibition in the presence of Cu2+. The addition of 1 mM EDTA countered the inhibition by 1 mM Mn2+ after 4 and 24 h, but 1 mM OPT did not counter the inhibition by 10 mM Mn2+ after 4 and 24 h. OPT countered the inhibition by 1 mM Zn2+ after 4 and 48 h. These trace elements inhibit aflatoxin B1 degradation by F aurantiacum. In addition, their presence necessitates higher concentrations (>1 mM) of EDTA and OPT for the removal of their inhibitory effect.
橙色黄杆菌NRRL B - 184具有在溶液和多种食品中降解黄曲霉毒素B1的能力。黄曲霉毒素B1是一种强效致癌物，给农业和食品工业造成了重大经济损失。为了了解橙色黄杆菌降解黄曲霉毒素B1所涉及的酶系统，研究了痕量金属离子（Cu2 +、Mn2 +、Zn2 +和Co2 +）的作用。同时也研究了在痕量金属离子存在下二价螯合剂（EDTA和1,10 - 菲啰啉[OPT]）的影响。将黄曲霉毒素B1（10微克/毫升）添加到已洗涤并重悬于磷酸盐缓冲液（pH 7.0）中的橙色黄杆菌72小时培养物中。使用高效液相色谱法测定这些培养物中黄曲霉毒素B1的浓度。在30℃下用1和10 mM的Cu2 +、Mn2 +和Zn2 +孵育细胞4小时和24小时后，显著降低了黄曲霉毒素B的降解（P < 0.05）。在48小时后，1和10 mM的Cu2 +和Zn2 +以及在24小时和48小时后0.1 mM的Cu2 +也观察到降解减少。Co2 +对黄曲霉毒素B1的降解没有显著影响。在Cu2 +存在下，EDTA和OPT没有抵消抑制作用。在4小时和24小时后，添加1 mM的EDTA抵消了1 mM Mn2 +的抑制作用，但在4小时和24小时后，1 mM的OPT没有抵消10 mM Mn2 +的抑制作用。在4小时和48小时后，OPT抵消了1 mM Zn2 +的抑制作用。这些微量元素抑制橙色黄杆菌对黄曲霉毒素B1的降解。此外，它们的存在需要更高浓度（>1 mM）的EDTA和OPT来消除其抑制作用。
