Flow Cytometric Analysis of Cellular Berberine Contents in High- and Low-Producing Cell Lines of<i>Coptis japonica</i>Obtained by Repeated Selection

Abstract

Cell lines that were highly productive for berberine were selected by repeated cloning of small cell aggregates. The berberine content of the highest-producing cell line increased after 4 clonings to 10% dw in comparison to the 3% dw found for the parent line, and the berberine yield was about 1,500 mg/1/14 days. There was no increase in berberine yield after the fifth cloning. Low-producing cell lines also appeared, even as the progeny of a highly productive cell line. We investigated the function of clonal selection in the enhancement of cellular berberine production. Flow cytometric analysis showed that high- and low-producing cell lines gave the fluorescence derived from the berberine contents of individual cells over essentially the same range of fluorescent intensity; but, the mode of fluorescence distribution shifted to a higher intensity with the increase in the berberine content of a cell line. This enhancement of berberine production because of cell selection must, therefore, be caused by a number of cells in a population that have high alkaloid contents, not by a uniform increase in the berberine content of all the cells.