- autoclave and employs steam under pressure - microbial destruction is caused by denaturation & coagulation of bacterial proteins by moist heat - Bacillus stearothermophilus: biological indicator - applicable to pharmaceutical preparations and materials: *withstand the required temperatures *penetrated but not adversely affected by moisture * It is not useful for oils, fats, oleaginous preparations, and other preparations not penetrated by moisture or for exposed powders that may