The Amino Acid Requirements of Oral Acidogenic Microorganisms Associated With Human Dental Caries

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Abstract
Species specific differences in amino acid requirements exist among the 4 oral acidogenic microorganisms most frequently associated with human dental caries. When grown in pure culture in a chemically defined synthetic medium containing all of the presently known nutritional essentials, the test strain of oral Lactobacillus acidophilus required glutamic acid, valine, serine, cystine, methionine, and phenylalanine. The test strain of Staphylococcus albus required proline, valine, and methionine. In contrast, growth of the oral strains of Streptococcus salivarius, glucose-fermenting Sarccharomyces. and mixed culture of all 4 organisms was not affected by the deletion of any 1 of the 19 amino acids studied, provided the other 18 were included in the test medium. Each chemical class of amino acids was essential for the 3 oral acid-producing bacteria in pure culture, whereas no single class was required by the glucose-fermenting Saccharomyces. provided the other 5 were present in the test medium. In contrast, acid production by the mixed culture of 4 test organisms was submaximal in the absence of any 1 of the 6 chemical classes of amino acids. The amino acid requirements of the oral L. acidophilus and S. albus were found to be strain specific as well as species specific.