Comparative evaluation of different methods of extraction and purification Used in technical enzyme production from microorganisms

Abstract

A study was conducted to compare the efficiency of two methods of microbial cell separation and enzyme purification using penicillin-G-acylase (PGA) from Escherichia coli. The efficiency of two methods of cell separation, centrifugation and cross flow filtration (CFF) were compared. The CFF method was found to have both higher separation efficiency and enzyme yield than centrifugation method. Centrifugation method gave a separation efficiency of 98.5% with enzyme yield of 94 % whereas CFF method resulted in 100% separation efficiency and enzyme yield of 98.8%. The Escherichia coli cells were disrupted by high pressure homogenization (HPH), and the disrupted cells were purified using two different techniques. Technique I was a combination of cross-flow-diafiltration (CFD), ultrafiltration (UF) and heat/pH-shift treatments. This technique resulted in 47% enzyme yield with a purification factor of 12. Technique II which involved two extraction steps by aqueous two - phase system (APS) coupled with UF resulted in 62% enzyme yield with a purification factor of 4. Technique I was therefore much better than technique II in purifying the enzyme. For higher enzyme yield, technique II would seem to be a better one than technique I.

Keywords: Enzyme yield, microbial enzymes, purification factor, recovery rate, separation efficiency, and technical enzyme

Tanzania J. Agric. Sc. (1998) Vol. I No.2, 141-148