Effect of low-dose ultrasonic treatment on Spirulina maxima

Spirulina maxima exposure to ultrasound (16 and 18 W) for 5 s generally resulted in decrease in growth, protein concentration, and superoxide dismutase (SOD) activity, while chlorophyll a concentration was not significantly affected at the 5% level. However, lower doses (8 W) of ultrasound showed a 5% increase in growth in samples receiving a one-time dose of ultrasound on the first day and day 7 of the experiment (US-D-1,7) compared to the control and the ultrasound every other day treatment (US-EOD). Chlorophyll a concentration was not significantly different between the control and US-D-1,7 treatment, but increased in the US-EOD treatment. In addition, protein concentration and SOD activity were decreased in both of the ultrasound treatments compared to the control. For the production of Spirulina on an industrial scale, low doses of ultrasound may provide an environmentally safe method for enhancing the growth of this organism. Conversely, higher doses of ultrasound may provide an environmentally safe method for reducing the growth of harmful cyanobacterial species in growth systems for animal aquaculture (C) 1998 Elsevier Science B.V. All rights reserved.