The comparison of the occurrence of enzymes effecting the deamination of dicarbon, aromatic and oxyamino acids, as well as transamination enzymes, in Citrobacter bacteria and the activity levels of these enzymes was made. The constant sign of such bacteria was the presence of serine and threonine dehydratase activity. 92% of the strains showed the presence of phenylalanine deaminase. No tryptophan activity was established. 96-98% of Citrobacter strains possessed phenylalanine, tyrosine and tryptophan aminotransferases with alpha-ketoglutaric acid functioning as the acceptor of the amino group.