There are available at present many ultrafiltration membranes which are reportedly capable of separating macromolecules at relatively high rates. In biological and biochemical recovery processes, it is often desirable to concentrate a moderate volume of a liquid containing a low concentration of biological active substance. These materials are often heat sensitive so that conventional techniques, such as vacuum evaporation, would not be desirable. This study will report the findings pertaining to the ability of two polyelectrolyte membranes (Diaflo, Amicon Corp., Lexington, Mass.) to concentrate enzyme and bacteriophage solutions. The influence of pressure, temperature, time, cations, and anions on the filtration rates will also be reported.
Blatt et al.
(1) have briefly reported on the ability of this type of membrane to concentrate protein solutions. They showed that the filtration flux through these membranes was 20 to 30 times higher than through the conventional cellulose dialysis membranes. The protein recovery efficiencies for these membranes were shown to be 90% or greater. The basic principle and method of manufacture of these membranes has been reported by Michaels (2).
Methods
(a) Chemicals and Reagents.
All inorganic chemicals were reagent grade.
(b) Penicillinuse Assay. Purified penicillinase was obtained through the courtesy of Yissum Research and Development Company, Hebrew University, Jerusalem, Israel. The enzyme was suspended in 0.1 M, pH 7.0, phosphate buffer (KH,PO, and NazHP04). The assay procedure of Citri (3) was used for determining the penicillinase activity. An enzyme unit for penicillinase is defined as the amount of enzyme that forms 277