ABSTRACT
This chapter is concerned with the bacteriological aspects of the problem of control of the bacterial microflora of the large bowel. The bacterial microflora of the large intestine of the adult is essentially a climax community in equilibrium with the environmental conditions imposed by the host and its composition determined by ecological interactions between the bacteria. The large intestine is the most heavily colonized region of the digestive tract. The major metabolic impact of the microflora in normal animals must result from its activities. Intestinal immunity may play a role in modulating bacteria-mucosa interactions. Direct evidence that the immune system has a controlling influence on the indigenous microflora is scarce. The gut bacteria have major effects on the development of many body systems particularly the anatomical form and functional efficiency of the gut. Among the more obvious differences between conventional and germ-free animals are cecal size and villous architecture.
