Application of Aqueous two-phase systems for the potential extractive Fermentation of Cyanobacterial products

The potential use of aqueous two-phase systems (ATPS) to establish a viable protocol for the in situ recovery of cyanobacterial products was evaluated. The evaluation of system parameters such as poly (ethylene glycol) (PEG) molecular mass, concentration of PEG and salt was carried out to determine the conditions under which Synechocystis sp. PCC 6803 cell and cyanobacterial products, i.e., β-carotene and lutein, become concentrated in opposite phases. PEG-phosphate ATPS proved to be unsuitable for the recovery of cyanobacterial products due to the negative effect of the salt upon the cell growth. The use of ATPS PEG-dextran (6.6% w/w PEG 3350, 8.4% w/w dextran 66900, TLL 17.3% w/w, V_R 1.0, pH 7) and (4.22% w/w PEG 8000, 9.77% w/w dextran 66900, TLL 18% w/w, V_R 1.0, pH 7) resulted in the growth of cyanobacteria (Synechocystis sp. PCC 6803) and the concentration of lutein in opposite phases. However, β-carotene was seen to concentrate in the top phase together with the biomass. The results reported here demonstrate the potential application of ATPS to establish the conditions for an extractive fermentation prototype process for the recovery of cyanobacterial products.