A model system for the study of bacterial colonization and growth on a hydroxyapatite (HT) surface is described. Hydroxyapatite was crystallized over the surface of porous glass beads. Chemical analysis of the product showed that the ratio of Ca2+/P042- was indistinguishable from that of commercial HT powder. X-ray diffraction analysis supported the conclusion that the product was HT. A system employing [14C]polyethylene glycol, which selectively adsorbs to the glass surface of the beads, was developed to determine the amount of glass surface covered by HT. Over 90% of the glass surface could be covered by our method. The product, HT beads, consisted of approximately 20% (dry weight) HT. The HT beads possess several properties which make them potentially useful for studying microbial adherence, growth, and interactions. These include: (i) chemical similarity to the tooth surface, (ii) large surface area, and (iii) high density. We also describe a method for direct measurement of the microbial mass of cells growing on beads. The method entails immobilizing a sample on a membrane filter (Millipore), staining it with amido black dye, and eluting the dye for spectrophotometric measurement. Streptococcus mutans served as the test organism. For free-growing bacteria the values measured with the filter assay were directly proportional to cell number, with a value of 1 mug of "protein" corresponding to about 1.5 X 10(6) colony-forming units, determined by viable count. For bacteria colonizing the beads, 1 mug of protein corresponded to about 2 X 10(7) colony-forming units on the beads during logarithmic growth. As the culture approached stationary phase, the efficiency of the assay decreased. These data indicate that multiple random samples, taken at a given time, are representative of the entire culture.
展开▼
机译：描述了用于研究细菌在羟基磷灰石（HT）表面上定居和生长的模型系统。羟基磷灰石在多孔玻璃珠的表面上结晶。产物的化学分析表明，Ca 2+ / P 042-的比例与市售HT粉末没有区别。 X射线衍射分析支持了该产物为HT的结论。开发了一种使用[14C]聚乙二醇的系统，该系统选择性吸附到珠子的玻璃表面，以确定HT覆盖的玻璃表面的量。我们的方法可以覆盖超过90％的玻璃表面。 HT珠产品约含20％（干重）HT。 HT珠具有多种特性，使其潜在地可用于研究微生物的附着，生长和相互作用。这些包括：（i）与牙齿表面的化学相似性，（ii）大表面积，和（iii）高密度。我们还描述了一种直接测量生长在珠子上的细胞的微生物质量的方法。该方法需要将样品固定在膜滤器（Millipore）上，用酰胺基黑色染料对其进行染色，然后洗脱该染料以进行分光光度法测量。变形链球菌用作测试生物。对于自由生长的细菌，用滤膜测定法测量的值与细胞数成正比，其中1杯“蛋白质”的值对应于约1.5 X 10（6）集落形成单位，由存活计数确定。对于细菌在小珠上定居，在对数生长过程中，1杯蛋白质相当于小珠上约2 X 10（7）个菌落形成单位。随着培养物接近固定相，测定效率降低。这些数据表明，在给定时间采集的多个随机样本代表了整个培养。
展开▼
