Beneficial changes in biomass and lipid of microalgae Anabaena variabilis facing the ultrasonic stress environment.

This study investigated the beneficial effects of ultrasonic treatment on the biomass, lipid and protein of the microalgae Anabaena variabilis. The microalgae after 11days cultivation (initial algae) were treated at the powers of 200, 350 and 500W for 10min and then cultured continuously for 3days (day 12-14). The power of 200W induced the highest lipid content 37.8% on day 12. The subsequent experiments tested the ultrasonic treatment times of 5, 10, 20 and 40min at 200W in the initial algae. The significantly improved lipid content 46.9% and productivity 54.2mg/L/d were obtained almost 1.46 and 1.86times more than that of the control algae respectively after 1day of continuous cultivation at 5min. The proper ultrasonic treatment showed the feasibility and high efficiency in promoting lipid accumulation without negatively influencing the biomass, fatty acid profiles and protein content.