2.3.1.59 additional information the enzyme may contribute to the O-acetylation of peptidoglycan 2.3.1.59 additional information enzyme may have a physiological role in secondary metabolism, its activity on aminoglycosides is simply fortouitous 2.3.1.59 additional information modification of antibiotics 2.3.1.59 additional information the enzyme contributes to the O-acetylation of peptidoglycan. Mutants that either underexpress or overexpress the aac(2')-Ia gene are characterized phenotypically to possess either lower or higher levels of peptidoglycan O-acetylation, respectively, compared to the wild-type. Providencia stuartii PR100, with 42-44% peptidoglycan O-acetylation compared to 54% of the wild-type, appears as irregular rods. Strains PR50.LM3 and PR51, with increased levels of peptidoglycan O-acetylation, 63% and 65% respectively, appear as coccobacilli or chain formers