The anaerobic bacterial flora of the mouse cecum

Refinements of the anaerobic technique such as the utilization of prereduced media and the removal of traces of oxygen from the gases used by passage through a hot copper oven resulted in quantitative and qualitative improvements in the recovery of anaerobic bacteria from the cecum of SPF mice. The commonest morphologic types of bacteria in the mouse cecum were tapered rods. These characteristically gave "speckled" colonies on agar plates. Those identified were species of the genera Fusobacterium, Eubacterium, and Clostridium. Several of the morphologic types seen with phase microscopy still could not be cultivated. The implications of these findings for the study of the intestinal flora are discussed.