Alterations in fecal microflora enzymes related to diet, age, lactobacillus supplements, and dimethylhydrazine.

The bacterial enzymes, beta-glucuronidase, azoreductase, and nitroreductase, have been measured in the fecal microflora of rats. The effects of diet, advanced age, Lactobacillus acidophilus supplements, and dimethylhydrazine on these microbial enzymes activities have been determined. The shift from a grain to a meat diet resulted in 1.5--2.5-fold increase in the activity of all three enzymes. Animals over 20 months of age, consuming a meat diet, showed further increases in fecal beta-glucuronidase activity, while the levels of all three microbial enzymes increased in old rats fed a grain diet. Feeding supplement of L. acidophilus significantly lowered the activity of fecal nitroreductase and azoreductase in meat-eating animals, but had no effect on nitroreductase activity in grain-fed animals. Dimethylhydrazine increased the fecal beta-glucuronidase activity in both grain- and meat-fed animals, but the carcinogen had no effect on nitroreductase or azoreductase activity. These findings have relevance to known features of the epidemiology and etiology of large bowel cancer, and suggest certain approaches to prevention.