American Journal of Clinical Nutrition, Vol 23, 132-140, Copyright © 1970 by The American Society for Clinical Nutrition, Inc.

Intestinal Flora of Folate-Deficient Mice

¹ From the Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York 14620

Comparison has been made between the aerobic bacterial population present within the proximal small intestine and colon of 20 weanling mice fed a folate-free diet and of a comparable group of mice who received a diet that contained folic acid.

Mice on the folate-free diet had a subnormal liver folate concentration and reduced weight gain within 1 week after weaning and developed diarrhea after 3 weeks.

The incidence of positive cultures for gram positive organisms was similar in the two groups of mice. Coliform organisms, on the other hand, were isolated more commonly from both segments of the intestine in the folate-deficient group. Coliform organisms were isolated from the jejunum in 95% of the deficient group versus 55% in the normal group. This difference was due principally to an increased occurrence of A. aerogenes and Proteus species in the intestinal tract of the deficient animals.

All of the coliform organisms, one-half of the enterococci, but only 6 of 25 members of the Lactobacillus species isolated were found to be capable of synthesizing folate. The principle form of folate synthesized by these bacteria was either 5-methyltetrahydrofolic acid or a triglutamate form of folate, since values assayed with L. casei exceeded, often by a value of a hundredfold, those obtained with S. faecalis assay. No difference was apparent between bacteria isolated from folate-deficient and normal mice in their capacity to synthesize folate, and the presence of coliform organisms within their proximal small intestine did not prevent the development of folate deficiency in mice receiving a diet devoid of this vitamin.