Effects of ultrasonic wave on the growth and fatty acid composition of Isochrysis zhanjiangensis

A three-factors and four-levels orthogonal experiment,including ultrasonic frequency,power and treatment duration,is conducted to study biological effect of ultrasonic treatment on Isochrysis zhanjiangensis.The experimental results suggest that ultrasonic frequency has significant biological effect,and ultrasonic power and treatment duration have less influence on this alga.The optimum ultrasonic conditions are 20 kHz,6 W,10 s (triplicate) for increasing the constant of growth rate of this alga,and 20 kHz,4~6 W,30 s for increasing its unsaturation degree of total fatty acids(TFA) and the percentages of major unsaturated fatty acids.The maximum constant of growth rate of Isochrysis zhanjiangensis can be 0.630 d which is 2.02 times of that of the controls.The maximum unsaturation degree can be 79.6% which was 7.8% higher than that of the controls.The percentages of major unsaturated fatty acids in TFA can increase more or less under the optimum ultrasonic conditions.