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PubMed1964

DEPENDENCY OF TREPONEMA MICRODENTIUM ON OTHER ORAL ORGANISMS FOR ISOBUTYRATE, POLYAMINES, AND A CONTROLLED OXIDATION-REDUCTION POTENTIAL.

Socransky, S. S. (Forsyth Dental Center, Boston, Mass.), W. J. Loesche, C. Hubersak, and J. B. Macdonald. Dependency of Treponema microdentium on other oral organisms for isobutyrate, polyamines, and a controlled oxidation-reduction potential. J. Bacteriol. 88:200-209. 1964.-Strains of Treponema microdentium can be cultivated on a variety of autoclaved commercially available media in the presence of other oral organisms. Organisms supporting growth in these circumstances include a facultative diphtheroid accompanied by either a strain of Fusobacterium or a motile gram-negative anaerobic rod. Culture filtrates and lysates of these "supporting organisms" failed to substitute for growing organisms. Measurement of the oxidation-reduction potential of the test system demonstrated that the spirochetes grew in a narrow range of Eh (optimum, -190 mv). The supporting organisms could be replaced by their filtrates when the Eh of the medium was poised in this range by a combination of reducing agents. Both filtrates contained a heat-labile factor required by the spirochete, which could be replaced by 5 mug/ml of cocarboxylase. Isobutyric acid, which could be detected in the fusiform filtrate, and putrescine which could be detected in the diphtheroid filtrate, replaced the spirochete's remaining filtrate requirement. Maximal growth occurred when any of the following were incorporated into the medium: 2 mug/ml of sodium isobutyrate; 250 mug/ml of putrescine dihydrochloride; 200 mug/ml of spermidine phosphosphate, or 150 mug/ml of spermine tetrahydrochloride.

Amines↗
PubMed1964

ELECTRON MICROSCOPY OF AXIAL FIBRILS, OUTER ENVELOPE, AND CELL DIVISION OF CERTAIN ORAL SPIROCHETES.

Listgarten, M. A. (Harvard School of Dental Medicine and Forsyth Dental Center, Boston, Mass.), and S. S. Socransky. Electron microscopy of axial fibrils, outer envelope, and cell division of certain oral spirochetes. J. Bacteriol. 88:1087-1103. 1964.-The ultrastructure of axial fibrils and outer envelopes of a number of oral spirochetes was studied in thin sections and by negative contrast. The axial fibrils measured 150 to 200 A in diameter. Only one end of each fibril was inserted subterminally into the protoplasmic cylinder by means of a 400 A wide disc. The free ends of fibrils inserted near one end of the cylinder extended toward, and overlapped in close apposition, the free ends of fibrils inserted at the other end. In thin sections, some axial fibrils showed a substructure, suggestive of a dense central core. The outer envelopes of most spirochetes appeared to consist of 80 A wide polygonal structural subunits. However, in one large spirochete, the outer envelope demonstrated a "pin-striped" pattern. Cell division in a pure culture of Treponema microdentium was studied by negative contrast. Results suggested that this organism divides by transverse fission, the outer envelope being last to divide. During the course of division, new axial fibrils appeared to originate on either side of the point of constriction of the protoplasmic cylinder. Flagellalike extensions which were found in rapidly dividing organisms were due to protruding axial fibrils, and appeared to be the result of cell division. Some evidence is presented to support the concept of a homologous origin for axial fibrils and flagella.

Cell Division↗
PubMed1964

ESTABLISHMENT OF HUMAN INDIGENOUS BACTERIA IN GERM-FREE MICE.

Gibbons, R. J. (Forsyth Dental Center and Harvard School of Dental Medicine, Boston, Mass.), S. S. Socransky, and B. Kapsimalis. Establishment of human indigenous bacteria in germ-free mice. J. Bacteriol. 88:1316-1323. 1964.-Thirteen strains of bacteria indigenous to the gingival crevice area of man were tested for their ability to establish as monocontaminants in germ-free mice. Three facultative organisms, Streptococcus mitis, Staphylococcus albus, and a "diphtheroid," established, as well as three anaerobes. Fusobacterium fusiforme, an anaerobic diphtheroid, and a Bacteroides strain. Seven other anaerobes (two strains of B. melaninogenicus, and one strain each of Treponema microdentium, Veillonella alcalescens, a Peptostreptococcus strain, Vibrio sputorum, and B. oralis) failed to establish. A mixture consisting of ten organisms representative of the predominant groups of cultivable bacteria present in the gingival crevice area of man was inoculated intraorally into germ-free mice. All organisms with the exception of B. melaninogenicus and T. microdentium became established as polycontaminants. Escherichia coli could be established in the above polycontaminated mice, as well as in those contaminated directly with human gingival debris. E. coli comprised approximately 50 and 6% of the fecal flora in the two groups, respectively. Diet, cecal contents, and feces of germ-free and polycontaminated mice were tested for inhibitory action against T. microdentium and B. melaninogenicus. None inhibited T. microdentium, whereas all three inhibited B. melaninogenicus. The inhibitory effect appeared to be due to dietary alfalfa. B. melaninogenicus could become established in mice monocontaminated with a facultative diptheroid and maintained on an alfalfa-free diet. These experiments indicate that human indigenous bacteria can become established in germ-free mice, and that microbial interactions and diet composition are important determinants.

Animals↗