title: Effect of culture medium and carbon dioxide concentration on growth of anaerobic bacteria and medium pH.
abstract: Two Danish agars, Danish Blood Agar (D.B.A.) and Anaerobic Agar (A.A.), were evaluated for their ability to support growth of 47 clinically isolated anaerobic strains in 5 different CO2-concentrations ranging from 0-10% CO2. CO2 and the use of an enriched medium (A.A.) are essential for satisfactory recovery of anaerobes. No gain could be seen when raising the CO2-concentration above 5%. The surface pH of the agars was measured both on non-inoculated and inoculated plates at room temperature and anaerobic incubation in the 5 different CO2-concentrations at 37 degrees C. Temperature change from room temperature to 37 degrees C resulted in a pH decrease of 0.1 units. There was a CO2-mediated decrease in pH (approximately 0.05 units/pr. CO2%) on non-inoculated media. On inoculated plates there was a minor additional fall in pH, which increased with time of incubation, but first became significant when the plates were incubated for more than 24 h. The use of 5% CO2 and A.A. is recommended for antimicrobial susceptibility studies on solid media.
mesh_terms: D001421:Bacteria, Anaerobic / Q000254:growth & development*; D002245:Carbon Dioxide / Q000378:metabolism / Q000494:pharmacology*; D003470:Culture Media; D006863:Hydrogen-Ion Concentration; D008826:Microbial Sensitivity Tests; D013696:Temperature
chemical_list: D003470:Culture Media; D002245:Carbon Dioxide