Enhancing starch production of a marine green microalga Tetraselmis subcordiformis through nutrient limitation

Characterization of cell growth and starch production in the marine green microalga Tetraselmis subcordiformis under extracellular phosphorus-deprived and sequentially phosphorus-replete conditions

“…subcordiformis FACHB-1751, a marine green microalga, was isolated from the Huanghai Sea near Dalian, Liaoning Province, China and maintained by the Freshwater Algae Culture Collection of the Institute of Hydrobiology (FACHB collection), Chinese Academy of Sciences. The microalgae were previously cultivated in natural seawater by adding nutrients, as described by Yao et al (2012). In the phosphorus deprivation experiment, algal cells were harvested during the late exponential phase and washed twice with phosphorus-free artificial seawater (ASW-P).…”

“…In the phosphorus repletion experiment, algal cells deprived of phosphorus for 4 days in the phosphorus deprivation experiment with the ICD of 1.5×10 6 cells mL −1 were washed twice with ASW-P and inoculated with an ICD of 1.5×10 6 cells mL −1 in ASW containing 0.5, 1.0, and 6.0 mM KH 2 PO 4 . The cells were cultured in a 600-mL glass air bubble column photobioreactor (50 mm diameter, 400 mm height) with a working volume of 500 mL and an aeration of 0.4 vvm with air containing 3 % CO 2 at 25±2°C as described by Yao et al (2012). The cultures were continuously illuminated from two sides with cool white fluorescent lamps that provided an incident light intensity of 200 μmol m −2 s −1 measured by a photosynthetically active radiation (PAR) detector (Optometer P9710 with PAR detector 3701, Gigahertz Optik Corporation, Germany).…”

“…The cell dry weight (DW) was determined gravimetrically according to Yao et al (2012). Maximum specific growth rate (μ max ) was evaluated from DW at exponential phase, calculated as follows:…”

“…Starch was determined as described by Yao et al (2012). Starch productivity (P s , in gram per liter per day) was calculated as follows:…”

“…Tetraselmis subcordiformis, a marine green microalga, has been proven to accumulate large amounts of starch in nitrogen-or sulfur-deprived environments (Yao et al 2012 subcordiformis. In the present study, extracellular phosphorus deprivation was used to test this alga's cell growth and starch accumulation ability at various ICDs.…”