Ultrasonic damages on cyanobacterial photosynthesis.

Excessive cyanobacterial growth in eutrophic water sources has been a serious environmental problem, and both sight preservation and drinking water production demand control of cyanobacterial growth in water. Ultrasonic treatment was reported to effectively inhibit cyanobacterial growth through vesicle collapsing and cell fracturing, but little was known about the change of cyanobacterial photosynthesis during sonication. This paper examined the ultrasonic inhibition of Microcystis aeruginosa cell growth and extracellular microcystins release, and the instant ultrasonic decreases of antenna complexes like cyanobacterial chlorophyll a and phycocyanins (PC), and the oxygen evolution rate. The results showed that sonication effectively damaged antenna complexes, slowed down the photo-activity, which significantly inhibited the cell growth and microcystins formation and release.