Selection of cell lines with high productivity of shikonin derivatives by protoplast culture of Lithospermum erythrorhizon cells.

Abstract
We selected high-yield cell lines, using protoplast culture of Lithospermum erythrorhizon cells. Three cell lines having different shikonin productivities were used as parent cells for the selection, and cell lines with high productivity were obtained efficiently in every case. The best cell line had 6.45g shikonin/g inoculum/23 days of production which was almost 1.5 times higher than that of the original cell line. The productivities of protoplast-derived cell lines were distributed widely and their average productivity was similar to the original one. The subculture of such a protoplast-derived cell line for eight months showed that its shikonin productivity was stabler than the original cell line.