Increased production of beta-carotene and glycerol in Dunaliella salina cell culture by ultrasound

Aim: The purpose of this study was to investigate the effect of ultrasound on growth and some physiological parameters in cultures of unicellular alga Dunaliella salina.
Material and Ultrasound waves were applied with a frequency of 40 kHz, and 5W/Cm3 power, at the fourteenth day of subculture in a completely randomized design with 3 replications. Ultrasound exposure times to cells were 0, 2.5, 5 and 10 minutes. The parameters measured were: cell growth, total protein content, photosynthetic pigments, antioxidant potential, membrane lipid peroxidation, amount of phenolic compounds, flavonoids, anthocyanins, soluble sugars, beta-carotene and glycerol.
The results showed, due to increase of ultrasound irradiation time, cell growth and photosynthetic pigments were decreased. In contrast, total protein content, antioxidant potential, membrane lipid peroxidation, phenolic compounds, flavonoids, anthocyanins, beta-carotene and glycerol were increased. Maximum amount of beta-carotene (12.3 mg/l) and glycerol (13.5 mg/l) as the main metabolites were obtained at 10 minutes treatment.
It seems that ultrasound waves increased beta-carotene, and glycerol production of the cell by induction of defensive responses and secondary metabolism.