Aspartame as a source of essential phenylalanine for the growth of oral anaerobes.

Phenylalanine and aspartic acid requirements were determined for 13 species of oral bacteria using the chemically defined medium OMIZ-W1. None of Actinobacillus actinomycetemcomitans, Bacteroides forsythus, Eikenella corrodens, Selenomonas sputigena, Treponema pectinovorum, T. socranskii, or Wolinella recta required either of these amino acid constituents of aspartame (L-aspartyl-L-phenylalanine methylester). Phenylalanine was essential for the growth of Capnocytophaga gingivalis, Eubacterium timidum, Fusobacterium nucleatum, Porphyromonas gingivalis, T. denticola, and T. vincentii, while aspartic acid was not required. With the exception of E. timidum, all phenylalanine-dependent strains could grow when the free amino acid was replaced by aspartame at concentrations at least 10-fold lower than those used for aspartame as an artificial sweetener.