Study Of Ultrasound Hormesis On Dunaliella Salina

To understand the ultrasound hormesis on microalgae, an ultrasonic processor was used to produce the ultrasound on Dunaliella salina. There were three treatment groups. For group 1, the exposure time was 2 seconds,8 seconds,32 seconds 64 seconds and 128 seconds, respectively. For group 2, the total exposure time was 128 seconds and 64 seconds. They were treated 16,8,4,2, and 1 time respectively. In group 3, the different time intervals were 0 second,2 seconds,4 seconds,6 seconds and 8 seconds. After the ultrasound exposure, the blank control group and treatment groups were simultaneously cultured under the same conditions. During this time, optical density, the content of chlorophyll a, Fv/Fm, yield and electron transport rate (ETR) were measured. The results indicated that (1) The ultrasound could promote the growth of Dunaliella salina. Optical density and the content of chlorophyll a were increased if it was treated with a proper dose of ultrasound; (2) For group 2, the growth was inhibited at first. If Dunaliella salina was treated for many times but short time span each time, from 4th to 7th day, the adverse effect could be reduced and even grew better; (3) With a 64 seconds and 128 seconds treatment, the growth of Dunaliella salina was inhibited, however, the groups treated with different time intervals showed no significant difference;. (4) In the recovering growth stage, Fv/Fm, yield and ETR were improved, indicated that ultrasound might have stimulated the overcompensation growth of Dunaliella salina.