TitleProduction of Vitamin B12 by Immobilized Cells of a Propionic Acid Bacterium
Publication TypeJournal Article
Year of Publication1982
AuthorsYongsmith, B, Sonomoto, K, Tanaka, A, Fukui, S
JournalEur J Appl Microb Biotechnol
Start Page70-74
Date Published06/1982

The ability of immobilized cells of propionic acid bacteria to form vitamin B12 has been investigated. Propionibacterium arl AKU 1251 having a considerable activity to produce the vitamin was selected as a test organism among six strains of propionic acid bacteria tested. The whole cells were entrapped with urethane prepolymers, photo-crosslinkable resin prepolymers or several other materials such as ?-carrageenan, agar or sodium alginate, and their vitamin B12 productivity was compared. Based on the criteria of the convenience of preparation and the stability of the cell-entrapping gels, a hydrophilic urethane prepolymer, PU-9, was employed as gel material. Satisfactory vitamin B12 production was obtained when 5–10 g of wet cells precultured to the late exponential growth phase were entrapped with 1 g of the prepolymer. Addition of a suitable amount of cobaltous ion and of 5,6-dimethyl benzimidazole to the culture medium was effective for the production of the vitamin by the immobilized cells. The repeated use of the immobilized cells was successfully achieved when a suitable amount of cells were entrapped and allowed the proliferation of cells inside gel matrices.