Kristen+W


 * Problem:** Is chocolate beneficial to the digestive system?
 * Hypothesis:** Dark chocolate will produce the largest colonies of lactobacillus casei because it contains the highest amount of cocoa.

30 petri dishes 375 mL liquid nutrient agar Parafilm marker 30 samples of lactobacillus casei 10 squares of dark chocolate 10 squares of milk chocolate hot plate graduated cylinder double boiler wooden spoon 1 centimeter graph paper transparency Incubator (35 degrees celsius is optimum) Inoculating loop
 * __Materials__**
 * __Procedure__**
 * 1) Prepare agar solution as directed on bottle
 * 2) Spread agar onto petri dish, evenly coating the bottom surface.
 * 3) Streak a sample of the lactobacillus casei in a zig-zag across the agar.
 * 4) Put on the lid of the dish and seal with tape.
 * 5) Place into incubator Repeat 9 more times.
 * 6) Follow steps 1 and 2
 * 7) Melt the dark chocolate in the double boiler, making sure the chocolate is not scorched.
 * 8) Measure out 1 mL of dark chocolate in the graduated cylinder.
 * 9) Add the dark chocolate to the agar.
 * 10) Repeat steps 3-5
 * 11) Repeat 9 more times.
 * 12) Repeat steps 7-11 only using milk chocolate instead.
 * 13) Repeat 9 more times.
 * 14) Label the first group of 10 no chocolate, the second dark chocolate, and the third milk chocolate.
 * 15) Allow samples to sit inside the incubator for 3 days.
 * 16) Remove samples from incubator.
 * 17) Place graph paper over each dish and shade in where colonies grew.
 * 18) Determine colony area by how many centimeter squares are shaded.
 * 19) Record colony sizes in data table.