Which of the following elements is involved in stabilizing the cell wall and endospores?

Calcium is a critical element in stabilizing both the cell wall and endospores in certain bacterial species. In the context of bacterial cell walls, calcium ions can form interactions with the negatively charged components of the cell wall, particularly in gram-positive bacteria, where they help to maintain cell wall integrity and stability. Additionally, in the formation of endospores, calcium plays a vital role in stabilizing the spore structure. It does this by helping to bind the core and the surrounding layers of the endospore, which is crucial for its resistance to extreme conditions.

Calcium's role in the structural integrity of these biological materials underlines its significance in microbial physiology, particularly in providing support and resistance to environmental stressors.