Efficient Bioproduction of Mycosporine-2-glycine, Which Functions as Potential Osmoprotectant, using Escherichia coli Cells

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Mycosporine-2-glycine (M2G) is known to be synthesized in halotolerant cyanobacterium Aphanothece halophytica. Escherichia coli cells in which the M2G synthetic genes of A. halophytica were introduced could synthesize M2G. Here, we report that M2G producing transformed E. coli cells showed salt tolerance compared to control cells. This result suggested that M2G could function as a potential osmoprotectant in E. coli. To our knowledge, this is the first report presenting the evidence that mycosporine-like amino acid confers salt tolerance on E. coli. Intracellular M2G content in the transformed E. coli cells were varied depending on NaCl concentration with maximum level at 0.75 M. Moreover, intracellular M2G level was affected by a supply of glycine with maximum level at 5 mM. In conclusion, we found that transformed E. coli cells could produce 205 μg of M2G/g fresh weight of cells under the best effective growth condition in this study. Thus, the results obtained here offer the potential for the bioproduction of mycosporine-like amino acids using the genetically engineered E. coli cells.