2004 Volume 37 Issue 7 Pages 842-849
Ultrafiltration behavior of Corynebacterium glutamicum (C. glutamicum) slurry was investigated with and without bovine serum albumin (BSA). It was found that the average specific filtration resistance αav of C. glutamicum slurry depended on slurry pH without BSA: αav was much lower in the pH from 2.0 to 4.0 than in the pH from 4.5 to 8.0. The measurement of particle size distribution and zeta potential of cells indicated that the area mean diameter and the surface charge of cells were maximum and minimum at pH 3.0, respectively. Such a change in the state of aggregation due to the decrease of surface charge reduced αav. Furthermore the effect of the mass fraction sb of BSA on αav was investigated under a constant total mass fraction s of BSA and cells at pH 4.5, where cells and BSA were oppositely charged. The addition of a small amount of BSA was effective below 0.08 of sb/s for reducing αav via aggregation of cells where BSA worked as a binder between cells. Over 0.08 of sb/s, however, αav increased due to the increase of free BSA of which αav was much higher than that of cells. The interaction manner of BSA and cells was found mono-layer adsorption of BSA to cells, following the Langmuir isotherm, according to the measurement of the adsorption amount of BSA to cells.
