Co‐existence of β‐lactamase and penicillin acylase in bacteria; detection and quantitative determination of enzyme activities

Twenty‐six bacteria were examined for the presence of penicillin acylase and β‐lactamase. A copper reducing assay, which was sensitive in the analytical range 2–20 μg/ml, was used for determination of penicilloates and a fluorescamine assay was used to determine 6‐aminopenicillanic acid concentrations when both substances were produced by the action of the enzymes on a single substrate. Seventeen bacteria contained β‐lactamases, six contained penicillin acylases and four contained both enzymes. Two bacteria contained a Type 1 penicillin acylase and four bacteria contained a Type II enzyme. No ampicillin acylases were detected. All β‐lactamases were constitutive enzymes in those organisms where both enzymes co‐existed. Bacillus subtilis and B. cereus produced inducible and extracellular β‐lactamases. Acinetobacter calcoaceticus ATCC 21288 produced a constitutive β‐lactamase which was detected extracellularly.