Ha mf millipore membrane

Quantification of storage lipids was performed as described in [27] (link), with modifications. Briefly, the algal suspensions were treated with dimethyl sulfoxide (DMSO) at a final concentration of 10% (v/v) and ethanol at a final concentration of 10% (v/v) in a 1.5 ml tube. 10 µl of Nile Red stock solution (100 µg/ml in ethanol) were added to the tubes and then they were incubated at 37°C for 10 min. Fluorescence intensity was quantified by a fluorescence spectrometer (F-2700; Hitachi, Tokyo, Japan) using 485 nm excitation and 570 nm emission. Glyceryl trioleate (T7140; Sigma, USA) stock solution (1 mg/ml in ethanol) was used as the lipid standard (in a range from 1 to 7.5 µg/ml) to obtain a calibration curve. For dry weight determination, cell cultures were filtered using a pre-weighed 0.45 µm HA MF-MILLIPORE MEMBRANE (Millipore Corp., Bedford, Mass.). The membrane was dried at 50°C for 2 hour and weighed on a microbalance.

The chlorophyll and phycocyanin contents were determined by spectrophotometric method according to Misumi et al. (2016) (link). Briefly, the cell culture was diluted with fresh medium to cell density of OD₇₅₀ = 0.5. Then absorbance was measured at wavelengths of 620 and 678 nm in a cuvette with a light path length of 10 mm by a spectrophotometer (UV-2600; Shimazu, Kyoto, Japan) equipped with an integrating sphere (ISR-2600Plus; Shimazu, Kyoto, Japan). The chlorophyll and phycocyanin contents were calculated as [Chl a] = 14.97 × A₆₇₈ – 0.615 × A₆₂₀ and [PC] = 138.5 × A₆₂₀ – 35.49 × A₆₇₈ according to Arnon et al. (1974) (link). For dry weight determination, cell cultures were filtered using a pre-weighed 0.45 μm HA MF-MILLIPORE MEMBRANE (Millipore Corp., Bedford, MA, USA). The membrane was dried at 50°C for 2 h and weighed on a microbalance.