ABSTRACT
The fecal flora contains relatively few facultative organisms such as enterococci, streptococci, and lactobacilli, and is dominated by nonsporing anaerobic bacteria, principally bifidobacteria, bacteroides, eubacteria, and propionobacteria. As most known carcinogens require metabolic activation in order to express their activity, it has been hypothesized that the fecal bacteria may contribute to the development of colon cancer by activating benign substrates in situ. Animal models for colon cancer have been developed that may be modified to examine the role that the fecal flora may play in this cancer. Polycyclic aromatic hydrocarbons are widely distributed environmental carcinogens that are commonly associated with the incidence of lung cancer. These hydrocarbons are detoxified via the liver as phenolic and dihydrodiol conjugates. N-Nitroso derivatives of secondary amino compounds comprise a series of potent carcinogens with a marked organ specificity. Such species may be synthesized by bacteria commonly found in the gastrointestinal tract acting on secondary amines in the presence of nitrate or nitrite.
