Cultivation under salt stress increases the concentration of recombinant miraculin in transgenic tomato fruit, resulting in an increase in purification efficiency

High target protein concentrations in source materials are important for achieving high purification efficiency. We sought to produce the taste-modifying protein, miraculin, in transgenic tomato fruits and then to extract and purify this protein. In order to improve the efficiency of recombinant miraculin purification from transgenic tomatoes, we tested a salt-stress cultivation technique aimed at increasing miraculin concentration in the tomatoes. Two lines of transgenic tomatoes, 56B and 5B, were grown under salt-stress conditions. There was a higher miraculin content per gram of fresh weight in transgenic tomatoes cultivated under salt stress than in tomatoes grown under non-stressed conditions. The observed increase in miraculin concentration was due to an enrichment effect caused by the miniaturization of tomatoes cultivated under salt stress. When the miraculin-enriched tomatoes were used for miraculin purification, the recovery rate of miraculin was higher.