What characterizes putrefaction?

Putrefaction is a biological process primarily characterized by the decomposition of organic matter, particularly proteins, due to the action of bacteria. During this process, bacteria break down tissues and produce various metabolic byproducts, including gases such as hydrogen sulfide, methane, and ammonia. The generation of these gases can lead to swelling and foul odors, which are typical signs of putrefaction.

The other options do not accurately describe putrefaction. Immediate freezing of biological tissues refers to a preservation method that halts decomposition, while chemical alteration by fixatives is a preservation technique used to prevent decay and maintain tissue structure for microscopic examination. The reduction of moisture in tissues can refer to desiccation, which is not a process associated with putrefaction, but rather a method of preservation or alteration. Thus, the defining characteristic of putrefaction is indeed bacterial decomposition accompanied by gas production.