title: A laboratory microcosm (artificial mouth) for the culture and continuous pH measurement of oral bacteria on surfaces.
abstract: A laboratory microcosm has been designed for the cultivation of bacteria on surfaces subjected to an adjustable supply of fluids. Bacteria are grown as a microbial film on halved premolar teeth, mounted back to back. Synthetic saliva is dropped slowly over the teeth throughout experiments. A nutrient supplement is provided at regular intervals. The drops of fluid retained by the teeth can be sampled for metabolic end-products. Alternatively, a miniature glass electrode may be set into one half of a tooth assembly to monitor the pH continuously at the stagnation site between tooth segments. Up to six replicate culture flasks and six electrodes can be accommodated in a single experiment. Satisfactory electrode performance was maintained during 66 h experiments. In initial 48 h experiments, teeth were inoculated with Streptococcus rattus BHT or 'Streptococcus mitior' LPA-1 in pure culture and provided with 1% (w/v) glucose for 1 h every 6 h. Bacteria produced typical responses to glucose feeds leading to the formation of 'Stephan'-like curves of pH-fall. Under these conditions, 'Strep. mitior' was more acidogenic than Strep. rattus and the pattern of acid production was distinct for each organism.
mesh_terms: D001431:Bacteriological Techniques; D001641:Bicuspid / Q000382:microbiology*; D003470:Culture Media; D006863:Hydrogen-Ion Concentration; D007773:Lactates / Q000096:biosynthesis; D019344:Lactic Acid; D009055:Mouth / Q000382:microbiology*; D012464:Saliva, Artificial; D013291:Streptococcus / Q000254:growth & development* / Q000378:metabolism
chemical_list: D003470:Culture Media; D007773:Lactates; D012464:Saliva, Artificial; D019344:Lactic Acid