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. 2017 Jul 25;12(7):e0181932. doi: 10.1371/journal.pone.0181932

Table 2. Peptidoglycan (PGN) quantification through the titration of meso-diaminopimelic acid (mDAP).

Strain mDAP amounta Relative PGN amount with regards to PAO1
PAO1 215.6 ± 17.5 1
PAΔDDh2Dh3 149.1 ± 9.1* 0.69*
PAΔDDh2Dh3 + pUCPAD 227.6 ± 15.4 1.05
PAΔDDh2 208.9 ± 4.2 0.97
PAΔDDh3 196.5 ± 5.0 0.91
PAΔDh2Dh3 220.3 ± 10.1 1.02
PAΔDDh2Dh3ΔC 193.1 ± 13.9 0.89
PAΔAG 219.5 ± 16.1 1.02
PAΔAG + pUCPCAC 157.5 ± 22.1* 0.73*
PAΔAG + pUCPC24 191.3 ± 12.0 0.89
PAΔnZ 211.5 ± 14.9 0.98

aThe peptidoglycan from selected strains was quantified by means of the titration of mDAP concentration, following the protocols described in Materials & Methods section. Bacterial cultures previously adjusted to ensure the same number of cells on each.The concentration of muropeptides was calculated using a mDAP standard curve, and the given value is the amount of mDAP (μg) purified from a 250 mL exponential culture adjusted to DO600 = 0.8. The results represent the mean ± SD from three different quantifications per strain.

*Statistically significant: P<0.001 in the One-way ANOVA with post hoc Tukey’s multiple comparison test (with regards to PAO1 strain). PAΔDDh2Dh3: knockout mutant on ampD, ampDh2 and ampDh3 genes; PAΔDDh2Dh3ΔC: knockout mutant on ampD, ampDh2, ampDh3 and ampC genes PAΔnZ: knockout mutant on nagZ. PAΔAG: knockout mutant on ampG. pUCPAD: pUC18-based Escherichia-Pseudomonas shuttle vector containing PAO1 AmpD gene. pUCPAC: pUC18-based Escherichia-Pseudomonas shuttle vector containing PAO1 AmpC gene. pUCP24: empty pUC18-based Escherichia-Pseudomonas shuttle vector.