Table 1.

Secreted activities of wild-type, pilD mutant, and complemented mutant bacteria

Activity assayedLevel of enzymatic activity within strain supernatants (mean ± SD)a
130b and 130b(pBBR1MCS)NU243 and NU243(pBBR1MCS)NU243(pMRL13)
Acid phosphatase+ (5.14 ± 0.61)b − (1.41 ± 0.06)b + (4.49 ± 0.12)b
Proteasec + (0.45 ± 0.02)− (0.05 ± 0.01)+ (0.44 ± 0.05)
Esterase-lipased + (37.46 ± 2.85)− (2.31 ± 0.67)+ (38.50 ± 1.83)
PLA+NDe
DNase++ND
RNase+ND
pNPPC-hydrolase+ (0.28 ± 0.04)− (0.00 ± 0.00)+ (0.31 ± 0.05)
  • a +, Wild-type level of activity; −, a significantly reduced or undetectable level of activity.

  • b The values in parentheses represent the mean and standard deviations from triplicate late-log cultures of either 130b(pBBR1MCS), NU243(pBBR1MCS), or NU243(pMRL13) and are representative of two additional complementation experiments. In all trials, the secreted activities exhibited by the uncomplemented mutant were significantly less than those of the wild type and the complemented strain (P < 0.0001, Student'st test). The complemented mutant behaved as did the wild type (P > 0.5).

  • c As measured by the azocasein assay.

  • d As measured by the release of pNP fromp-nitrophenyl caprylate.

  • e ND, not determined.