Characteristics of an Induced Variant of Bacterionema matruchotii

Abstract

Bacterionema matruchotii, a calcifiable filamentous organism, was treated ultrasonically. The disrupted cells produced typical colonies that developed macroscopic globular structures. A nonfilamentous, pleomorphic variant was derived from the globules. The variant retained the calcification potential of the filament, as well as fermentation and ultrastructural similarities.Bacterionema matruchotii, a filamentous organism of the human oral biota, is known to form intracellular calcium hydroxyapatite,1-4 the major mineral of vertebrate calcification. Spontaneous coccal and bacillary variants described by Streckfuss and Smith5 also have been shown to calcify.6 The purposes of this study were to determine whether an induced pleomorphic variant of B matruchotii retained the capacity to calcify, and to compare the fermentation profile and ultrastructure of the variant with the parent organism. The variant, a mixture of coccal and bacillary cells, was derived by sonification of B matruchotii. Materials and MethodsThe variant was obtained by selective cultivation of ultrasonicallydisrupted B matruchotii, Richardson strain 13. Exponential growth-phase cells, harvested from brainheart infusion (BHI) agar,a were water-washed and suspended in sterile deionized water. The suspension was sonicated at 20,000 cycles per secondb for five minutes at 4 C to achieve a 957,%, cell breakage. The debris was spread Scientific, Rochester, NY. on BHI agar and incubated at 37 C for seven days. Globular structures that developed on some of the colonies were subcultured on the same type of medium. Atypical colonies appeared in three days and yielded a mixture of coccal and bacillary forms. These colonies retained the nonfilamentous heterogeneity on subcultivation and were designated F75B.To determine whether F75B had the capacity to calcify, the organism was grown seven days at 37 C in the chemically defined medium of Ennever, Vogel, and Streckfuss.7The cells were harvested by centrifugation at 1(0,000 g for five minutes at 5 C and waterwashed. Most of the yield was ashede at 55 C for two hours. The residue was examined by previously described X-ray diffraction and electron microscopic techniques.7 To provide a negative control, Actinomyces naeslundii, West Virginia strain 45, a noncalcifying organism, was processed parallel to F75B.The parent filament and F75B were compared for fermentation profiles by inoculating each organism into a series of 12 tubes of heart infusion agar,d each of which contained a 1% concentration of a different carbohydrate (Table). Fermentation was determined by pH measurements after seven days growth at 37 C.B matruchotii and F75B were prepared for ultrastructural examination by fixing five-day BHI agar colonies with 3% glutaraldehyde in cacodylate buffer (pH, 7.2), followed by 1P% osmium tetroxide. The samples were dehydrated in ethanols, embedded in epoxy resine and sectioned at 600 Af The sections c Coleman 40 Radio-Frequency Low Temperature Asher, Coleman Instruments,

A microbiological study of dental calculus.

“…In the present experiments, in addition to B. tiiatrttdioiii, the Gram-positive rods from calculus which calcified were the unidentified eatalase positive rod and A. ttaes-iundii. This result does not .support that of Ennever et al (1972) or of Streckfuss, Smith & Ennever (1973) who used A. naesiuttdii as a negative control for calcification when mieroorganisms were incubated in a synthetic medium containing calcium, or that of Wasserman et al (1958) who showed calcification of both live and dead colonies of A. israeiii after 6 days suspension in calcifying fluid. However, Bowen and Gilmour (1961) produced calculus-like deposits on teeth using both facultative and anaerobic actinomyees cultured in a ealcifying medium for a period to 3 weeks -17 months and in the experiments of Rizzo et al (1962) both A. israeiii and A. naeslundii produced hard deposits after 3-8 months.…”