Which of the following best describes how heavy metals can control microbial growth?

• A. They hydrolyze peptidoglycan in bacterial cell walls.
• B. They act as oxidizing agents, producing free radicals that damage DNA.
• C. They denature proteins by binding to functional groups, thereby inactivating enzymes.
• D. They disrupt cell membranes by dissolving lipids.

Answer: (C)

Verified step by step guidance

1. Understand that heavy metals control microbial growth primarily through their interaction with cellular components rather than by physically breaking down structures like peptidoglycan or lipids.
2. Recall that heavy metals have a high affinity for binding to functional groups in proteins, such as sulfhydryl (-SH) groups, which are critical for maintaining protein structure and enzyme activity.
3. Recognize that when heavy metals bind to these functional groups, they cause protein denaturation, which means the proteins lose their three-dimensional structure and, consequently, their function.
4. Understand that enzyme inactivation due to protein denaturation disrupts essential metabolic processes in microbes, leading to growth inhibition or death.
5. Conclude that the best description of how heavy metals control microbial growth is by denaturing proteins through binding to functional groups, thereby inactivating enzymes.