Optimization of Polymer/Salt Aqueous Biphasic System (ABS) for Direct Recovery of Recombinant Bacillus Subtilis Protease

Mei Qi Gan, Phei Er Kee, Yin Hui Chow and Hui Suan Ng

Faculty of Applied Sciences, UCSI University, UCSI Heights, 56000 Cheras, Kuala Lumpur, Malaysia.

Centre for Research and Graduate Studies, University of Cyberjaya, Persiaran Bestari, 63000 Cyberjaya, Selangor, Malaysia.

School of Engineering, Taylor’s University, Lakeside Campus, No.1, Jalan Taylor’s 47500 Subang Jaya, Selangor, Malaysia.

*Corresponding author email: grraceng@cyberjaya.edu.my


Introduction: The growing market demand for protease in various industries has sparked the interest among researchers to develop a simple, cost-effective and high yield method for the downstream recovery of proteases.

Objective(s): In this study, the partitioning behavior of recombinant Bacillus subtilis protease and different parameters are investigated using polymer/salt aqueous biphasic system (ABS).

Methodologies: Res1ponse surface methodology (RSM) and Box-Behken design (BBD), the multivariate statistical methodology, were employed to optimize the specific parameters including composition of polymer, composition of salt and pH of the biphasic system in order to achieve optimal partition coefficient and recovery yield of protease.

Results: The optimized ABS was exhibited at 17.50%(w/w) of polyethylene glycol (PEG) 1000 and 20.34%(w/w) of potassium phosphate, 20%(w/w) of crude feedstock, at pH 8.2, room temperature and without addition of sodium chloride (NaCl). Proteases preferentially partitioned to the PEG rich top phase with high partition coefficient of 5.387 and relatively high recovery yield of 84.82% were obtained although there are technical errors existed in the partition coefficient model analysis.

Conclusion: The results achieved with the optimized system held great promise on ABS, the single-step operation capable of surpassing conventional downstream processing methods and applying in the large-scale production of protease.

Keywords: Protease; Aqueous biphasic system; Response surface methodology; Box-Behken design; Polyethylene glycol