What are the two major categories of toxin produce by bacteria

There are two general categories of toxins which differ in potency and function:

Endotoxins, which are part of the cell wall of Gram-negative bacteria. Only small amounts may escape into surrounding fluids from living bacteria. Greater amounts are released when the bacteria die and their cell walls disintegrate. Endotoxins are less potent, and larger amounts are needed to induce disease symptoms. Also, they are heat resistant and cannot be converted into toxoids.

Exotoxins are mainly proteins that are secreted by a bacterial cell into surrounding fluids, and are produced by both Gram-negative and Gram-positive bacteria. Most are readily destroyed by heat, but they can be converted into toxoids that are used as vaccines. Exotoxins are extrememly powerful biological poisons as in the case of tetanus, where it has been estimated that 1 mg of purified tetanus toxin could kill millions of mice.