Miraculin, derived from the miracle fruit (Synsepalum dulcificum), is a taste-regulating protein that interacts with human sweet-taste receptors and transforms sourness into sweet taste. Since miracle fruit is cultivated in West Africa, mass production of miraculin is limited by regional and seasonal constraints. Here, we investigated mass production of recombinant miraculin in carrot (Daucus carota L.) callus cultures using an air-lift bioreactor. To increase miraculin expression, the oxidative stress-inducible SWPA2 promoter was used to drive the expression of miraculin gene under various stress treatments. An 8 h treatment of hydrogen peroxide (H₂O₂) and salt (NaCl) increased the expression of miraculin gene by fivefold compared with the untreated control. On the other hand, abscisic acid, salicylic acid, and methyl jasmonate treatments showed no significant impact on miraculin gene expression compared with the control. This shows that since H₂O₂ and NaCl treatments induce oxidative stress, they activate the SWPA2 promoter and consequently up-regulate miraculin gene expression. Thus, the results of this study provide a foundation for industrial-scale production of recombinant miraculin protein using transgenic carrot cells as a heterologous host.

中文翻译：

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使用气举生物反应器在转基因胡萝卜愈伤组织悬浮培养物中大规模生产重组奇迹蛋白。

奇迹分子（Synsepalum dulcificum）衍生的奇迹蛋白是一种调味蛋白，可与人的甜味受体相互作用并将酸味转变为甜味。由于奇迹水果是在西非种植的，因此奇迹蛋白的大量生产受到地区和季节限制。在这里，我们调查了使用气举式生物反应器在胡萝卜（Daucus carota L.）愈伤组织培养物中大量生产重组奇迹蛋白的情况。为了增加奇迹蛋白的表达，在各种胁迫处理下，使用氧化应激诱导的SWPA2启动子来驱动奇迹蛋白基因的表达。过氧化氢（H ₂ O ₂）和盐（NaCl）使奇迹蛋白基因的表达比未处理的对照组增加了五倍。另一方面，与对照相比，脱落酸，水杨酸和茉莉酸甲酯处理对奇迹蛋白基因表达没有显着影响。这表明，由于H ₂ O ₂和NaCl处理诱导氧化应激，因此它们激活SWPA2启动子并因此上调了奇迹蛋白基因表达。因此，这项研究的结果为使用转基因胡萝卜细胞作为异源宿主的工业规模生产重组米拉克林蛋白提供了基础。