Abstract

JACHLEWSKI, Silke; BOTES, Marelize  and  CLOETE, Eugene T. The effect of ultrasound at 256 KHz on Microcystis aeruginosa, with and without gas vacuoles. Water SA [online]. 2013, vol.39, n.1, pp.171-174. ISSN 1816-7950.

The effect of ultrasound on the growth of M. aeruginosa confirmed to contain gas vacuoles and on a laboratory culture with no gas vacuoles was investigated. Both cultures were treated continuously for 9 d with an ultrasonic flow device. To evaluate the influence of ultrasound during the treatment, the chlorophyll-a concentration was measured daily. Furthermore, changes in culture characteristics, e.g., flotation and gas vesicle formation, were determined. The results showed that, in contrast to the control, both ultrasonic-treated cultures had a lower chlorophyll-a concentration and cell aggregates were disrupted. Transmission electron microscopy confirmed a collapse of gas vacuoles in the environmental culture, while the laboratory culture, which did not contain gas vacuoles, showed many membrane-damaged cells. It was concluded that ultrasonic treatment of M. aeruginosa caused the disruption of gas vacuoles and destruction of cell membranes.

Keywords : Ultrasound; cyanobacteria; Microcystis aeruginosa; chlorophyll; gas vacuoles.

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