Flow Cytometric Analysis of Cellular Berberine Contents in High- and Low-Producing Cell Lines of Coptis japonica 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.