Recovery of intracellular ectoine from Halomonas salina cells with poly(propylene) glycol/salt aqueous biphasic system

Abstract

Abstract Ectoine is a compatible cell protectant sourced from halophilic and halotolerant microorganisms. Various biotechnological applications of ectoine have urged the development of cost-effective downstream processing of ectoine. Aqueous biphasic system (ABS) composed of poly(propylene) glycol (PPG) 425 and salt was adopted for the recovery of intracellular ectoine from Halomonas salina DSM5928T fermentation. Phosphate, citrate and sulfate salts were evaluated for their effects on the recovery of intracellular ectoine using the PPG/salt ABS. In this study, ectoine exhibited a salt-rich bottom phase preference in the PPG/salt ABS because of the hydrophilic surface properties of ectoine. The effects of concentrations of PPG 425 and salts, crude load, pH and concentrations of neutral salts (NaCl and KCl) on the recovery of ectoine were investigated. Optimum recovery of intracellular ectoine was obtained with ABS (pH 5.5) composed of 30% (w/w) PPG 425 and 20% (w/w) sulfate; 15% (w/w) crude load; and 1.5% (w/w) of KCl. High yield of 94.7% of intracellular ectoine was successfully recovered from H. salina cells with an enrichment factor (EF) of 1.7 and a purity of 87.03%.