Question

Date Name Lab Report: 15 Control of Microbial Populations: Effects of Heat 1. What was the purpose of this experiment? Complete the following table with your observations: Growth (yes/no) Name of the bacterium Heat treatment time (min) o s 10 20 30 40 1 3. Thermal death time for: Bacillus subtilis at 100°C Staphylococcus aureus at 100°C 4. Define thermal death time.

Answer 1

Answer 1: Different bacteria have different resistance capabilities against heat stress. The purpose of this experiment is to study the effect of heat exposure time on the growth of different bacterial species.

Answer 2: To complete the table with observation laboratory experiment is necessary. The two bacterial species Bacillus subtilis and Staphylococcus aureus are to be separately treated with heat (100 ⁰C). The binary data of growth or no growth should be noted at the time, 0, 5 min, 10 min, 20 min, 30 min and 40 min. Then, the comparison for the resistance capabilities has been made between the two bacterial species.

Answer 3: The thermal death time for:

Bacillus subtilis at 100 ⁰C is reported in a study to be at 20 min.

Staphylococcus aureus at 100 ⁰C – Studies have shown that Staphylococcus aureus at 80 ⁰C has a thermal death time of 20 min. Therefore, the thermal death time for Staphylococcus aureus at 100 ⁰C is speculated to be quicker than 20 min.

Answer 4: The thermal death time is the time of exposure of an organism to a specific higher temperature that inhibits growth and cause the death of the organism.