Question

You have isolated a new species of bacterium, Mustget caffeinum, from a compost heap that was heavily enriched with coffee grinds. You discover that it can grow using caffeine as its only carbon source but seems to grow better on other carbon sources, You decide to compare its growth rate in defined minimal media (MM) supplemented with either sucrose or caffeine as the sole carbon source. You inoculated M, caffeinum into both MM-caffeine and MM-sucrose at 8 AM. Because this species is flamentous, its growth is most accurately measured by dry weight. At regular intervals throughout the day, you vigorously mix the culture, remove 10 mL, filter the cells onto a pre-weighted filter paper disk, dry the disk in a 40 degree C oven, and weight the disk. You graph the calculated net weight of the cells over time and determine that both cultures reaches exponential phase by 9 AM. You use the following measurements to calculate the generation times.

Answer 1

M.caffenium would grow better on MM- sucrose , because inspite of reaching exponential phase at the same time in both the media, the bacteria grown in MM-sucrose has more dry weight at exponential phase as compare to dry weight of bacterium grown in MM-caffeine.