黄曲霉和寄生曲霉在地上的 Nyjer 种子上产生黄曲霉毒素 B1（AFB1）：水分活度和温度的影响。
Aflatoxin B1 (AFB1) production by Aspergillus flavus and Aspergillus parasiticus on ground Nyjer seeds: The effect of water activity and temperature.
机构信息
Department of Chemistry and Physics, Purdue University Northwest, Indiana, USA.
Department of Biological Sciences, Purdue University Northwest, Indiana, USA.
出版信息
Int J Food Microbiol. 2019 May 2;296:8-13. doi: 10.1016/j.ijfoodmicro.2019.02.017. Epub 2019 Feb 21.
Nyjer oil seed cake supports high levels of aflatoxin B1 (AFB1) production. AFB1 is a secondary metabolite of Aspergillus flavus and A. parasiticus, classified as a Class 1A carcinogen. The aim of this study was to determine the effects of temperature (20, 27, and 35 °C) and water activity (0.82, 0.86, 0.90, 0.94, and 0.98 a) on fungal growth and AFB1 production of A. flavus and A. parasiticus on ground Nyjer seeds over a 30-day incubation period. Linear regression models indicated that both fungal growth and AFB1 production were significantly influenced by water activity of Nyjer seeds and incubation temperature. The two fungi did not grow on Nyjer seeds at 0.82 a at the three incubation temperatures. The most favorable growth conditions for both fungi were 0.90-0.98 a at 27 °C or 0.90-0.94 a at 35 °C. The optimum temperature for AFB1 production was 27 °C for both A. flavus and A. parasiticus (with regression coefficients of 6.01 and 9.11, respectively). Both fungi were likely to produce high levels of AFB1 at 0.90 a (with regression coefficients of 3.56 for A. flavus and 7.17 for A. parasiticus). Aspergillus flavus only produced AFB1 on seeds with 0.90-0.98 a at 27 °C (in the range of 203-282 μg/kg) and on seeds with 0.90 a at 35 °C (212 μg/kg). No detectable AFB1 was produced by this fungus in any other culture conditions that were studied. Aspergillus parasiticus, in contrast, was able to produce AFB1 under all of the growth conditions. At 20 °C, this fungus produced the highest level of AFB1 (212 μg/kg) at high water activity (0.98 a). At 27 °C, A. parasiticus produced high levels of AFB1 (in the range of 209-265 μg/kg) at a wide range of water activities (0.86-0.98 a). In the entire study, the highest AFB1 concertation for A. parasiticus was detected on seeds incubated at high temperature (35 °C) and low water activity (0.86 a). The findings of this study could help optimize the storage conditions of Nyjer oil seeds to reduce aflatoxin contamination.
黑种草子饼可以支持黄曲霉毒素 B1（AFB1）的大量产生。AFB1 是黄曲霉和寄生曲霉的次生代谢物，被归类为 1A 类致癌物。本研究的目的是确定温度（20、27 和 35°C）和水活度（0.82、0.86、0.90、0.94 和 0.98 a）对黑种草子上黄曲霉和寄生曲霉生长和 AFB1 产生的影响，在 30 天的孵育期内。线性回归模型表明，水活度和孵化温度都显著影响真菌的生长和 AFB1 的产生。在三个孵化温度下，这两种真菌都不能在水活度为 0.82 a 的黑种草子上生长。两种真菌最适宜的生长条件为 27°C 时水活度为 0.90-0.98 a，或 35°C 时水活度为 0.90-0.94 a。对于 AFB1 的产生，两种真菌的最佳温度均为 27°C（回归系数分别为 6.01 和 9.11）。两种真菌都有可能在水活度为 0.90 a（黄曲霉的回归系数为 3.56，寄生曲霉的回归系数为 7.17）时产生高水平的 AFB1。黄曲霉仅在 27°C 时水活度为 0.90-0.98 a（范围为 203-282μg/kg）和 35°C 时水活度为 0.90 a（212μg/kg）的种子上产生 AFB1。在研究的任何其他培养条件下，这种真菌都没有检测到可检测到的 AFB1。相比之下，寄生曲霉能够在所有生长条件下产生 AFB1。在 20°C 时，该真菌在高水活度（0.98 a）下产生最高水平的 AFB1（212μg/kg）。在 27°C 时，寄生曲霉在较宽的水活度范围（0.86-0.98 a）下产生高水平的 AFB1（范围为 209-265μg/kg）。在整个研究中，寄生曲霉在高温（35°C）和低水活度（0.86 a）下孵化的种子上检测到的 AFB1 浓度最高。本研究的结果可以帮助优化黑种草子油种子的储存条件，以减少黄曲霉毒素污染。
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