Under an approximate 10X magnification, this image depicts the colonial characteristics displayed by Streptococcus pneumoniae bacterial colonies that were grown on primary isolation medium, consisting of trypticase-soy-agar, containing 5% sheep’s blood, as well as 5mg of gentamicin/ml. See PHIL 10863 for another view of this culture.
The S. pneumoniae bacterial inoculum were harvested from a primary nasopharyngeal, i.e., throat swab. The culture plate was stored under modified atmospheric conditions by using a candle-extinction jar, thereby, bringing about an approximate 3% increase in carbon dioxide.
Note that the so called doughnut-shaped colonies are those of Streptococcus pneumoniae. Those that do not have depressed centers are not S. pneumoniae.