Which of the following is characteristic of gram-negative bacteria regarding endotoxin?

Gram-negative bacteria are known for possessing an outer membrane that contains lipopolysaccharides (LPS). Endotoxin refers to the lipid portion of LPS, which is known to be heat-stable. This stability is significant because it indicates that the endotoxin can withstand high temperatures without losing its biological activity, making it a concern in sterilization processes. When gram-negative bacteria are lysed, they release endotoxin into the environment, which can trigger severe immune responses, such as fever and septic shock.

The characteristic heat stability of endotoxin differentiates it from exotoxins produced by some bacteria, which are often heat-labile and can be denatured by heat. Understanding the properties of endotoxins is essential for microbiology, particularly in clinical contexts, as it helps in recognizing the potential dangers of infections caused by gram-negative bacteria.