The content of chlorophyll-a (Chl) and total carotenoids (TCs) was determined using the method by Zavrel et al. [52 (link)]. 1000 µL of culture were centrifuged at 10,000 rpm for 10 min at 4°C, then the supernatant was discarded, and 1 mL of neutralized methanol was added to the pellets. The samples were left overnight in the fridge and then homogenized using three cycles of 10 min of vertexing and ultrasonic bath. The solutions were then centrifuged for 10 min at 10,000 rpm and the supernatant analyzed spectrophotometrically for chlorophyll-a and total carotenoids at λ = 720 nm and λ = 665 nm, respectively, with methanol as a blank at λ = 470 nm. The concentrations were estimated using the correlations proposed by Ricthie [53 (link)] for total carotenoids and Wellburn [54 (link)] for chlorophyll-a. Then, the procedure outlined by Lobban et al. [55 ] was utilized to perform the analysis of phycobiliproteins (phycocyanin (P) and allophycocyanin (APC)). 1000uL of a 0.1 M PBS with a pH of 7 were added to the pellets and subjected to ultrasonic treatment for two hours at 30 °C in a water bath. The resulting mixture was then centrifuged at 14,000× g for 10 min, and the supernatant was transferred to a clean Eppendorf tube. The absorbance for each sample was measured at 565 nm, 615 nm, 652 nm, and 720 nm and the concentration of phycobiliproteins was determined by Bennet and Bogorad equations [56 (link)].
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