Abstract
Enzyme activities and bacterial populations were compared in single stage, two stage (pH=5 and 7), and two stage with cell recycling continuous cultures of mouse faecal microbiota. Results were compared to in vivo findings in the mouse caecum and faeces in order to choose the system which best models the ecology of the murine lower intestinal tract. Fecal homogenates had higher numbers of total aerobes and lactose fermenting enterics than caecal homogenates. The microbial balance of the continuous culture systems more closely resembled the faecal microbiota (the culture inoculum) than the caecal microbiota. Lactobacilli numbers were significantly lower in single stage cultures than in two stage cultures or in vivo samples. Enzyme activities were comparable between culture types, with the exception of β-glucuronidase, which was closest to the in vivo level in single stage cultures. Because no one in vitro system proved superior with regards to all the parameters studied, the choice of which system to use may be based largely on the study purpose.