Question

Identify the risk associated with improper or overuse of antibiotics.

Why is moist heat more efficient at killing microbes than dry heat? How does an autoclave kill microbes so efficiently?

Why do some microorganisms produce antibiotics, and how do they avoid being harmed by the antibiotics they produce?

Answer 1

=> The risk associated with improper or overuse of antibiotics is the emergence of antibiotic resistance. Microbes may develop mutations which allow them to survive against the antibiotic. These mutations can be transferred to other bacteria through horizontal gene transfer via plasmids or conjugations.

=> Moist heat is more effective at killing microbes than dry heat because moist heat can penetrate microbial cells and kill them by denaturing their proteins and or may melt lipids in their cytoplasmic membranes. Unlike moist heat, dry heat radiates and thus cannot penetrate well. An autoclave uses moist heat under pressure to sterilize substances. The standard condition for autoclave is 121°C at 15 psi for 20 minutes.

=> Microbes make antibiotics as a defense against other microbes competing for resources. Antibiotic producing microbes avoid being killed as they may lack the molecule being targeted by the antibiotic. They may have altered cell membrane and receptors to prevent binding of antibiotic. They may also contain resistant proteins such as antibiotic resistance enzyme which can degrade the antibiotic. The antibiotic producer may also modify its own receptors so the antibiotic if it attack the cell.