Question

. Which of three bacterial strains, namely, Bacillus subtilis, Staphylococcus epidermidis, and Escherichia coli shows greater sensitivity to ultraviolet (UV) radiation? Brainstorm the reasons for differences in the susceptibility of bacteria to ultraviolet radiation.

Answer 1

Sensitivity order (Most sensitive to least sensitive)
E. coli > Staphylococcus epidermidis > Bacillus subtilis

UVB radiation can easily penetrate into the nucleus of E coli as it is a gram-negative bacteria with less protective covering.
Staphylococcus epidermidis is a gram-positive bacteria with thick peptidoglycan layer that protects against UVB radiation.
Bacillus subtilis is most resistant to UV because
1. Formation of thick endospores
2. Photochemistry of DNA within spores
3. Highly active DNA repair mechanisms during spore germination