Genetic Heterogeneity in Bacteroides asaccharolyticus (Holdeman and Moore 1970) Finegold and Barnes 1977 (Approved Lists, 1980) and Proposal of Bacteroides gingivalis sp. nov. and Bacteroides macacae (Slots and Genco) comb. nov.

Abstract

Strains of Bacteroides asaccharolyticus (Holdeman and Moore 1970) Finegold and Barnes 1977 (Approved Lists, 1980) which had been isolated from human mouths, most often from periodontal pockets, showed remarkably little deoxyribonucleic acid base sequence homology with the deoxyribonucleic acid of strains of the same species which were isolated from nonoral sites. In addition, four strains of catalase-positive Bacteroides melaninogenicus subsp. macacae Slots and Genco 1980 isolated from periodontal pockets in monkeys were distinct from B. asaccharolyticus. With deoxyribonucleic acid immobilized on membrane filters and index deoxyribonucleic acid made radioactive by translation repair with [3H] thymidine triphosphate, we found that the deoxyribonucleic acid homology among the three groups could readily be distinguished by their deoxyribonucleic acid base contents. The nonoral strains had 51 to 52 mol% guanine plus cytosine, the human oral strains had 46.5 to 48.5 mol% guanine plus cytosine, and the monkey catalase-positive strains had 42 to 43 mol% guanine plus cytosine in their deoxyribonucleic acids. Some strains which fit the species description of B. asaccharolyticus were not genetically related to the three groups. A new species, Bacteroides gingivalis sp. nov., which comprises those strains that resemble B. asaccharolyticus but have 46.5 to 48.5 mol% guanine plus cytosine, is described. These strains can also be distinguished serologically and by their production of phenylacetic acid. The type strain is Slots’ strain 2561 (=ATCC 33277). Bacteroides melaninogenicus subsp. macacae, which is comprised of the monkey isolates which resemble B. asaccharolyticus but which have a guanine plus cytosine content of 42 to 43 mol% and give a positive catalase reaction, is elevated to species status. Its name is thus Bacteroides macacae (Slots and Genco) comb. nov. The type strain of this species is Slots’ strain 7728-L6C (=ATCC 33141).