抄録
Flux decline behaviors on ultrafiltration of Corynebacterium glutamicum (C. glutamicum) slurry were investigated with and without protein, BSA, using washed cell slurry to eliminate the effect of metabolites and medium ingredients. A dead-end cell with UF membrane was employed, and the filterability was evaluated by average specific resistance αav, which is inversely proportional to filtration rate. First, the effect of pH on ultrafiltration behaviors of C. glutamicum slurry was investigated without BSA. The resistance αav of C. glutamicum slurry rapidly decreased with decrease of pH below pH 4.5, and minimized at pH 3.0. According to the measurement of particle size distribution, cells tended to aggregate in such pH range. Thus aggregation of cells caused decrease of αav. Secondly, 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. Addition of BSA was effective for reducing αav via aggregation of cells below 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, over 0.08. The interaction manner of BSA and cells was found mono-layer adsorption of BSA to cells, following Langmuir isotherm, according to the measurement of adsorption amount of BSA to cells.
