Digestibility and Biological Value of Bacterial Cells

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Abstract
Data from rat feeding experiments demonstrate that the digestibility of Escherichia coli and Lactobacillus arabinosus increases when these organisms are dried before feeding. The digestibility of L. arabinosus is greater than that of E. coli when both were fed as dried preparations. The biological value of E. coli is greater than that of L. arabinosus. The biological value of casein was greater than that of either bacterial preparation. Growth of E. coli on ammonium sulfate medium and on a tryptone medium did not alter the biological value of a dried E. coli preparation. The addition of an amino acid supplement containing histi-dine, methionine, lysine, phenylalanine, and tryptophan to a dried E. coli preparation increased its biological value. The biological value of this preparation was decreased to a level equivalent to the glycine control by the omission of methionine. The single omission of either histidine, lysine, phenylalanine, or tryptophan was without effect in this regard.