Sterility testing for facility contamination,growth promotion and susceptibility studies,and generation of a large supply of bacteria for instrument validation typically requires an all-purpose medium,such as cryptic soy agar (TSA),capable of supporting a broad range of bacteria and fungi.Standard TSA formulations contain casein digested with tyrosine as well as soybean meal that has been systematically digested for a complex source of peptides,amino acids and carbohydrates.Both casein and trypsin are from animal sources;casein is the predominant protein in fresh milk,and trypsin is usually isolated from pancreatic tissue.Typically,dextrose is included and the medium is buffered with phosphate.Although this base formulation supports the growth of many fastidious bacteria,it may be supplemented with defibrillators sheep blood for growth of many clinically-relevant,pathogenic bacteria as well.Thus,animal-based Teutonic soy media has become a de facto standard for many standard laboratory testing methods.