14A-16

E. Y. LEE¹, G. J. Woo², and J. Park¹. (1) Dept. of Biotechnology, Yonsei University, Seoul, 120-749, South Korea, (2) Central Research Laboratories, Easy Bio System, Inc., 81-1, Kunsu-ri, Jiksan-myon, Chunan-si (Choong Nam), 330-810, South Korea

Hen egg white (HEW) lysozyme has broad potential as a natural food preservative due to its selective bactericidal activity. High purity HEW lysozyme has been successfully separated from 13 different HEW proteins by discontinuous ultrafiltration in a previous study. For obtaining large amounts of HEW lysozyme, a scale-up of ultrafiltration and the optimization of operating parameters were needed.

The objective was to determine the optimum separation membrane and operating conditions.

HEW (0.25%, w/v) dissolved in a citrate-phosphate buffer was prefiltered with three microfiltration membranes (GF/A, GF/D, and GF/F) and then ultrafiltered with three ultrafiltration membranes (PM30, PN03C, and PN01E). The influence of operating conditions such as feed flow rate, inlet pressure, temperature, time, and pore size on lysozyme permeability was studied. The purity of lysozyme was confirmed by electrophoresis.

The optimum pH of citrate-phosphate buffer to precipitate other HEW proteins was determined as pH 5.1. GF/D was the most suitable prefiltration membrane maintaining its flux of 1,000 LMH (L/m²/hr) for 26 min. The feed flow rate had a little effect on flux. The effect of inlet pressure on flux was different depending on membrane material and pore size. The flux of prefiltered solution was high in the order of high temperature (20^oC>10^oC>0^oC). Permeate flux of PM30 dropped rapidly during the first 5 min and then stabilized itself at about 16 LMH, while that of PN01E and PN03C membrane declined linearly with time. Although there was some loss of lysozyme during the ultrafiltration process, the purification factor had increased 3.3 fold to the origin. After ultrafiltration with PM30, only the lysozyme band could be observed in the lane.

Ultrafiltration was a effective method for the separation of antimicrobial lysozyme and PM30 showed the highest flux among three hollow fiber membranes regardless of operating conditions.