Abstract
This study aimed at elucidating information concerning the conditions under which the cell of Lactobacillus leichmannii #4797 takes up vitamin B_<12> in its resting state. Such information might help understand the chemical reaction involved in the combination of intrinsic factor and B_<12> as well as a situation in the intestinal lumen where some flora compete with the mucosa for B_<12>. Vitamin B_<12>-^<60>Co was mixed with resting cells or cell walls prepared by breaking up the cells, under various conditions and the uptake of B_<12> was measured in the precipitated cells or cell walls. The uptake of B_<12> by this strain is specific in comparison with other lactobacilli which do not require B_<12> for the growth. The uptake reaction was little affected by temperature and was quite fast, inhibited by high concentrations of salts. There seems to be a certain equilibrium between the amounts of the cell and B_<12>. The reaction was not influenced by Tween 80 or trypsin digestion, but was inhibited by amylase, lipase, heat and formaldehyde. The surface binding reaction seems to be a nonenzymatic physical adsorption involving an ionic combination of B_<12> with a surface structure.
