Cell destruction level and metabolites green-extraction of Tetraselmis suecica by low and intermediate frequency ultrasound

•The US power, frequency and sonication time influence on cell lysis mechanism.•Low US power at 20 kHz extracts proteins while maintaining cells membrane integrity.•High US power at 20 kHz causes cell membrane bursting and coiling.•100 kHz irradiation results in a simple cell deflation and low protein yield.•US extraction is more efficient with low cell concentration. Low (20 kHz) and intermediate (100 kHz) frequency ultrasound (US) were studied for their efficiency on cell destruction and metabolites extraction of the microalga T. suecica. This study revealed different levels of cell destruction. Firstly, the prolonged irradiation of US at low frequency allowed the extraction of 90% of total proteins and 70% of carbohydrates by rapidly inducing at high power (100 W or 200 W) a coiling up phenomenon of the cell walls on themselves. A low power (50 W) over short times allows extracting proteins by the perforation of the cells without destroying them, opening the perspective of milking. Furthermore, the use of 100 kHz frequency, showed lower yields of metabolites as well as a low level of cell destruction, resulting in a simple deflation of the cells.