Table 4.

Resistance against organic acids, hydrophobic agents, antimicrobial peptides, and the complement

StrainResistance to organic acids (% survival)aMIC (μg/ml)bSerum resistance (% survival)c
SDSNovobiocinPolymyxin BProtamine
P27459 -S5.7 × 10−3 ± 2.9 × 10−33000.7512.533785 ± 13 (5)
P27459galUNDd1500.1871.5684ND
P27459galU/pTrcAkanND1500.187NDND  0.21 (1)
P27459galU/pACYCgalUND3000.7512.5337100 (3)   
P27459res297.6 × 10−5 ± 8.9 × 10−51500.1871.56840.6 ± 1 (4)  
P27459res29/pACYC177ND1500.187NDND1.1 ± 1.6 (2) 
P27459res29/pACYCgalUND3000.7512.5337100 (3)   
P27459 ΔgalE::cmND3000.7512.533781 ± 26 (2) 
P27459 ΔwbeW5.8 × 10−3 ± 1.7 × 10−33000.756.251680.006 ± 0.0056 (2)
P27459 ΔwbeW/pACYC177NDNDND6.251680.001 ± 0.0019 (2)
P27459 ΔwbeW/pJNwbeWNDNDND12.5337100 (2)   
P27459res1180 1500.0470.78210.0003 ± 0.0004 (2)
  • a Survival of wt and mutant strains in response to short-chain organic acid challenge. Cells were grown in LB (pH 7) and subsequently shocked in LB (pH 4.4) containing 8.7 mM acetic acid, 2.5 mM butyric acid, and 3.7 mM propionic acid. Approximately 109 CFU/ml was used in each experiment. Percent survival at 60 min was calculated by comparison with the initial number of cells measured at time zero. Data shown are the average from triplicate experiments ± standard deviation.

  • b All experiments were performed in triplicate.

  • c Calculated as 100 × (number of CFU after cells were incubated for 1 h in 20% normal human serum/number of CFU after cells were incubated for 1 h in 20% heat-inactivated normal human serum). Indicated is the mean ± standard deviation. The numbers of independent experiments are given in parentheses.

  • d ND, not determined.