SPECIES DIFFERENTIATION OF ORAL LACTOBACILLI FROM MAN INCLUDING DESCRIPTIONS OF LACTOBACILLUS SALIVARIUS NOV SPEC AND LACTOBACILLUS CELLOBIOSUS NOV SPEC

It is easy to assume from the literature that the oral lactobacilli are a group of variants representative of the species Lactobacillus acidophilus. Indeed, results obtained by the conventional Hadley (1933) technique for the enumeration of oral lactobacilli have been expressed almost exclusively as the "L. aidophilus or L. A. count". Furthermore, Rosebury (1944) in a review on "The Parasitic Lactobacilli" has expressed a prevailing view of the dental literature that "L. acidophilus is the designation used here to include all aerobic parasitic lactobacilli. " Bergey's Manual (1923) states that the lactobacilli are microaerophilic. In order to avoid confusion, it seems necessary to explain that the Hadley (1933) technique is one in which an appropriate dilution of saliva is streaked by means of a glass rod on the surface of solid tomato agar (pH 5.0) plates. The "aerobic parasitic lactobacilli" mentioned above are those capable of growth under these conditions. However, with the same medium and incubation under reduced oxygen tension it is obvious that these "aerobic parasitic lactobacilli" grow optimally under microaerophilic, if not anaerobic, conditions. Rodriguez (1930, 1931) had developed a method for cultivation of the oral lactobacilli based on this property. In other words, the oral lactobacilli are not unique in this respect from the general behavior of the members of the genus. Various attempts have been made to define the taxonomic status of the oral lactobacilli. Xligler and Gies (1915) have been quoted often since they were among the earliest who studied the lactobacilli from the mouth. Although they accepted the designation Bacillus acidophilus (Moro) for their strains, they recognized 3 types from the limited number of tests conducted. Furthermore, they considered that "the pleomorphic bacillus undoubtedly belongs to the acidophilus or acidific group' of organisms found in human and animal feces. " Dental and intestinal strains have been compared by Morishita (1928, 1929), Rosebury, Linton, and Buchbinder (1929), Hadley and Bunting (1932), Hadley, Bunting, and Delves (1930), and others. Morishita observed differences in antigenicity and the utilization of carbohydrates whereas the others considered these strains as variants representative of "L. acidophilus". Warner and Arnold (1941) also concluded that "oral aciduric bacilli do not appear to be a group separate and distinct from Lactobacillm acidophilus of Moro. "2 The role of L. acidophilus in dental caries, either as an etiological agent or an index organism of expected caries experience, has been emphasized repeatedly. At least 100 references can be cited. Occasionally the terms Bacillus acidophilus, B. acidophilus, Lactobacillus acidophilus-odontylicus, L. odontylicus, or similar epithets have been employed. The authors have studied the available extant strains of Anderson and Rettger (1937), Enright, Friesell, and Trescher (1932), Curran, Rogers, and Whittier (1933), and Morishita (1928, 1929). All the intestinal strains were typically L. acidophilus, and nearly every dental strain remaining from the foregoing investigations was L. casei. It is not surprising therefore that, except for Curran, Rogers, and Whittier (1933) who did not study agglutination reactions, these 1 Italics ours. 2 The authors have studied this strain from the Kral Collection and have confirmed the finding of Orla-Jensen, Orla-Jensen, and Winther (1936) that this is not a lactobacillus but rather Microbacterium lacticum.