1980 Volume 35 Issue 3 Pages 539-548
An experiment was carried out to determine whether the cellular amino acids and proteins of Bifidobacterium bifidum harbored in the intestinal tract could be utilized by the host. In it germfree and conventional mice were administered orally with live cells of B. bifidum labelled with [3H] leucine, as well as heat-killed cells and cytoplasmic extracts derived therefrom. Radioactivity in the serum was followed in these animals over a 7-day experimental period.
Four different types of samples were prepared from radiolabelled B. bifidum for administration by the aid of a gastric tube. They were (i) suspension of live cells, (ii) suspension of heat-killed cells, (iii) cytoplasmic extract, and (iv) heated cytoplasmic extract. In conventional mice, radioactivity was recovered from the serum at appreciable rates within 1 hour after administration, reaching a maximal level at the 4th to 8th hour with a subsequent gradual decrease. The recovery rate in these animals was dependent on the type of samples. It was the highest in mice administered with sample (ii) and rather low in mice administered with sample (i). Radioactivity was the lowest in mice administered with samples (iii) and (iv). On the other hand, the recovery rate was higher in germfree mice administered with sample (i) than in those administered with sample (ii).
These results led to the following conclusions. When mice were administered orally with live cells, heat-killed cells, or cytoplasmic extracts of B. bifidum, amino acids and proteins contained in this organism were absorbed from their intestinal tract and utilized efficiently. The efficiency of their intestinal absorption depended significantly on the type of cells or extract administered and on the state of the intestinal flora.
