Table 1.

β-Lactamase activities of crude extracts ofC. meningosepticum CCUG 4310 and E. coli DH5α(pBlaA-4c)a

SamplebSp act (μmol/min/mg of protein) against:
NitrocefinNitrocefin EDTAImipenemImipenem EDTA
CCUG 4310, not induced0.1820.127 (69)c 0.078<0.005
CCUG 4310, induced0.1970.134 (68)0.083<0.005
DH5α(pBlaA-4c)0.4650.458 (98)<0.005 NAd
DH5α(pACYC184)<0.010NA<0.005NA
  • a The basal activity of E. coli DH5α(pACYC184) is also shown for comparison. Data represent mean values for three measurements. The standard deviations were always lower than 10%.

  • b The crude extracts of CCUG 4310 were prepared from exponentially growing cultures, either without antibiotic (not induced) or with ampicillin (25 μg/ml) added 2 h before collection (induced). The crude extracts of E. coli strains were prepared from early-stationary-phase cultures.

  • c The values in parentheses are the percentage of the activity measured with nitrocefin alone.

  • d NA, not assayed.