The effect of an audible and low ultrasound frequency on the growth of synchronized cultures of Scenedesmus obtusiusculus

Abstract

The effects of sonication of synchronized cultures of Scenedesmus obtusiusculus Chod. were examined. Two frequencies, 4 kHz and 19 kHz were applied during various phases of the diurnal mitotic cycles. As a result of 4-kHz sonication the average cell division decreased. During exposure to 19-kHz sonication the average rate of cell division initially increased slightly, but mitotic division was subsequently inhibited when the cells were exposed to prolonged sonication. A "relaxation" period of two generations was required before the cells regained their normal rate of productivity (cell number increase). The cells were more sensitive to sonic shock during the first quarter of their 24-h life cycle and apparently insensitive during the last quarter. No chromosomal effect was observed. It is suggested that sonication alters specifically timed events that occur at the earlier stages of the life cycle.