Calcification of Selected Strains of Streptococci JOSEPH L. STRECKFUSS, WILLARD N. SMITH, LEE R. BROWN and MARION M. CAMPBELL The University of Texas Dental Science Institute, P.O. Box 20068, Houston, Texas 77025

J Dent Res 58(9):1916-1917, September 1979 In 1960, Ennever reported that Bacterionema matruchotii forms intracellular calcium phosphate deposits with X-ray maxima essentially identical to those of calcium hydroxyapatite (Ennever, J Periodont 31:304, 1960). Since then, 14 other oral isolates from man and marmoset, including four enteric species, five serotypes of cariogenic Streptococcus mutans, and one strain of Streptococcus sanguis, have been found to calcify under similar experimental conditions (Ennever et al., J Dent Res 51:1483, 1972; Streckfuss et al., J Bacteriol 120:502, 1974). This study was undertaken to determine whether other oral streptococci also possess the capability of calcification (Brown et al., J Dent Res 52: 815, 1973; DHEW Pub No (NIH) 74-286, 1973). S. mitis ATCC 6249 and four laboratory stock strains of S. mitis S21, S23, S32 and S34 were examined, along with S. salivarius ATCC 13419, S. faecalis ATCC 8043 and S. bovis ATCC 9809. A non-calcifiable S. salivarius 125C was used as a control (Ennever et al., op. cit.). Each organism was grown in synthetic calcification medium for two weeks at 370C and processed for X-ray diffraction and electron microscopy as previously reported (Ennever etal., JDentRes 50:1327, 1971). The test isolates produced X-ray diffraction patterns characteristic of apatite with diffuse bands indicating small crystals. Electron micrographs confirmed the X-ray findings, and also disclosed dispersed extracellular deposits in S. mitis S21 and S. faecalis ATCC 8043, in addition to the

Received for publication December 22, 1978 Accepted for publication January 18, 1979

intracellular mineral (Fig. 1 B and D). S. mitis S21 produced beads of mineral along membrane structures (Fig. 1 B) and S. mitis ATCC 6249 developed almost whole calcified cells (Fig. 1 A). S. salivarius ATCC 13419 (Fig. 1C) and S. bovis ATCC 9809 (Fig. IE) produced only intracellular apatite. Each of the isolates retained cell wall integrity except for S. faecalis ATCC 8043 in which some lysis was evident. Mineral was not detectable by either X-ray or electron microscopy in the non-calcifiable S. salivarius 125C (Fig. 1F). Intracellular mineral appeared associated with membrane structures in S. mitis S21 and S32 and as discrete cytoplasmic clusters in S. salivarius, S. faecalis and S. bovis. S. mitis ATCC 6249 displayed completely calcified cells, indicating a greater ability of some cells to mineralize. Although this feature is infrequently seen in the streptococci, it has been previously observed in S. mu tans SLi (Streckfuss et al., op. cit.). Extracellular mineral was found in S. mitis S21, S34 and in S. faecalis. Some lysis was noted in S. faecalis, which may account for the release of intracellular crystals. Lysis was not as evident in S. mitis S21 and S34, which also produced extracellular mineral. Apatite is not formed if lysis occurs in early growth. Lysis of cells subsequent to apatite formation probably results in the appearance of the extracellular deposits. The present findings demonstrate that many strains of the permanent and transient streptococcal species which inhabit the mouth can calcify and, as such, may participate in the formation of mineralized dental accretions.

1916 Downloaded from jdr.sagepub.com at Bobst Library, New York University on July 11, 2015 For personal use only. No other uses without permission.

Vol. 58 No. 9

STR EPTOCOCCI CA LCIFICA TION

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1ig. 1 E lectron micrographs of isolates. A. S. mitis ATCC 6249, intracellular and calcified cell. B. S. mitis S21 representative of S23, S32, and S34 showing intracellular calcification at membrane structures (arrow) and dispersed extracellular mineral. C. S. salivarius ATCC 13419, intracellular deposits. D. S. faecalis ATCC 8043, intra and extracellular crystals (arrow). E. S. bovis ATCC 9809, intracellular crystals. F. Non-calciflable S. salivarius 125C. Marker bar: 500 nm. Downloaded from jdr.sagepub.com at Bobst Library, New York University on July 11, 2015 For personal use only. No other uses without permission.

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Calcification of selected strains of streptococci.

Calcification of Selected Strains of Streptococci JOSEPH L. STRECKFUSS, WILLARD N. SMITH, LEE R. BROWN and MARION M. CAMPBELL The University of Texas...
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