Preparation of an experimental low-fluoride diet from single-cell organisms for rats and mice

1. A method for producing a standard low-fluoride diet from a green alga and yeast is described. Chlorella pyrenoidosa was grown in a culture medium prepared with distilled water and analytical grade chemical salts. The spent culture medium from the alga culture was reclaimed and replenished with salts and sucrose for the production of yeast, Saccharomyces cerevisiae. 2. The single-cell organisms were separated by centrifugation from their culture media and the dried cells were blended with sucrose, maize oil, cellulose and a salt mix to produce diet pellets for rats and mice. 3. The diet was readily accepted as food by rats and mice and it was found to contain 100-300 micrograms fluoride/kg dry weight. Two generations of rats and four generations of mice were bred on this diet. 4. The use of hydroxyapatite to reduce the fluoride content of the chemical used in the production of the alga and yeast biomass was investigated. Diet pellets prepared with this biomass contained 45-60 micrograms fluoride/kg dry weight.