Table 4.

Comparison of OXY β-lactamase activities of chromosomal and plasmid-mediated β-lactamase genes

Strain/plasmidβ-Lactamase promoteraOXY β-lactamase activityb
ChromosomePlasmid
SL781/noneWild type82 ± 12
SL7811/noneMutant20,000 ± 2,490
SL781/pBF9Wild typeWild type1,980 ± 284
SL781/pBF10Wild typeMutant48,500 ± 8,950
  • a The mutated promoter carries the mutation G→T at the first base of the −10 consensus sequence.

  • b See footnote b of Table 2 for units of β-lactamase activity. All measurements were made with at least three independent determinations.