ABSTRACT
The vitamin B 12 Productivity of 14 marine bacterial strains isolated from the China Sea was determined microbiologically using Escherichia coli 113 3. Tests were made on the culturing media and culture conditions for Vitamin B 12 production. The results showed that the culturing medium in which the extract from soybean cake with seawater and some nutriments were added was suitable to recognize further some marine Vitamin B 12 producing bacterial strains. The medium with appropriate cobalt chloride and some salts added may be useful for Vitamin B 12 biosynthesis. The PH value of the fermentation for the testing strains was raised with the lapse of time for fermentation. A better Vitamin B 12 production may be obtained by keeping the fermentation liquid slightly basic till about 96h. No.2627 strain in all the strains tested showed well in the productivity. The mixed cultivation of some strains (including No.2627 strain) tested often has potentiality and superiority for Vitamin B 12 production.