The goal of this enrichment culture was to isolate the organism Streptococcus thermophilus. First we chose the environment from which we would like to isolate the bacteria from: yogurt. We then researched which organisms are used in the production of yogurt and chose one to isolate. Next, we investigated the type of media and environmental conditions that would best support this organism.
Our hypothesis was
that we would be able to successfully isolate S. thermophilus if
certain conditions we had researched were provided during growth.
One condition is the use of HYA agar, which provides digested enzymes (proteose
peptone #3) and three sugars (glucose, lactose, and galactose) that the
organism is able to metabolize. These plates were incubated at 37
degrees Celcius, which allows for maximum growth. We found the recipe
for the HYA agar in Atlas' Handbook of Microbiological Bacteria.
book stated that this media would allow for the growth of
or Lactobacillus bulgaris.