[Role of the digestive flora in adaptation to lactose consumption in rats].

Part of the digestive flora in the adaptation to lactose consumption. Lactase activity was determined with adult Wistar rats. Some of which were accustomed to lactose since weaning. For this purpose, the tissue of jejunum, the flora of the ileum, the caecum and the large intestine were examined. When the rats received a high lactose diet, the lactase of the jejunum is more active because of both the intestinal tissue development and a higher production of enzyme by protein unit. But the main source of lactase is the digestive flora of the animal: a lactase flora develops in the ileum, the large intestine and mainly the caecum. The caecum lactase represents about half of the total lactase activity. The flora of the animal which has not consumed lactose since weaning can develop a noticeable lactase activity after 7 hr of incubation in presence of lactose. It is also the caecum flora which shows the greatest capacity of adaptation to lactose.