Repeated harvest of vacuole-located secondary product from in vitro grown plant cells using 1.02 MHz ultrasound

Summary

Beta vulgaris L. (red beetroot) cells from a suspension culture were sonicated with continuous wave ultrasound (1.02 MHz) for periods ranging from 10 s to 60 s. In general, cells sonicated for ≥ 30 s released vacuole-located pigment into the surrounding medium, whereas cells sonicated for < 30 s and control (unsonicated) cells released no pigment. Sonicated cells were viable as determined using fluorescein diacetate: microscopic examination of a selected population of sonicated cells did not show any signs of obvious structural damage. Sonicated cell samples were subcultured to re-establish actively growing, pigment-competent cell cultures. Cells from such cultures were available for further harvests of the pigment by sonication. For sonication periods ≥ 50 s, repeated cycles of sonication and incubation allowed pigments to be harvested from cells every 7 days during a 21-day culture period.