Streak on the starch agar plates

“Lab 5 Microbial Nutrition” “BIO250L”

Student Name: Christine Mochama

Access Code (located on the lid of your lab kit):

“Experiment 1- Bio-Prospecting for Starch Degrading Bacteria”

“Table 3: Gram Iodine Analysis”

“Sample”

“Growth on Starch Agar (yes or no)”

“Clear Area Around Bacteria?”

“Is Sample Capable of Degrading Starch?”

“A”

Yes Yes Yes
“B”

Yes No No
“C”

Yes Yes Yes
“D”

Yes No No
“Post-Lab Questions”

“1. Why was cow manure used as a potential source of starch degrading bacteria?”

Cow feces contain a high amount of starch and low amounts of proteins. Additionally, the cow manure has amylase present in it, which is vital for breaking down starch into small molecules. This is because the cows tend to consume more fiber reducing the need for amylase.

“2. What are some other potential sources for starch degrading bacteria?”

Other potential sources for starch degrading bacteria include food, fermentation, paper, and textile industries. This is because the above has the potential of producing amylase necessary for starch degradation. One of the commonly used bacterial species is bacillus 3.

“3. What component makes the starch agar selective for amylase degrading bacteria?”

Grams iodine is the component that will make the starch agar selective for amylase degrading bacteria. Gram iodine reacts with the starch and stains it purplish, bluish or blackish. In the absence of carbohydrates, it will be colorless.

“4. Why were each of the following steps performed in this experiment?”

“a. Serial dilution”

Serial dilution was for the reduction of the concentration of the bacteria or cultures. This enables the counting of organisms or easier handling since there is a lowered level in a particular sample.

“b. Growth on the nutrient agar plates."

Agar plates were used as they provide a conducive environment for the growth of microorganisms. It feeds them and acts as a nutrient providing culture for these bacteria. Additionally, agar is indigestible to organisms meaning that they cannot eat it, which would lead to the destruction of the plate.

“c. Streak on the CMCA plates."

The streak on the CMCA plates was used to isolate a single pure strain of the microorganisms (bacteria). This enables the study of the single strand to conclude it.

“Insert photo of your cultures after incubation with your name clearly visible in the background:”