Table 5. Growth of PA14, the SBP penta mutant, and strains of the penta mutant complemented with individual SBPs in minimal medium supplemented with di/tripeptides as the sole nitrogen source^a.

N source	PA14 wt		ΔdppA1–A5		DppA1		DppA2		DppA3		DppA4
	Bb	OD600 c	B	OD600	B	OD600	B	OD600	B	OD600	B	OD600
Ala-Ala	++	0.55±0.02	++	0.13±0.05 d	++	0.59±0.04	++	0.38±0.21	++	0.70±0.04	+++	0.43±0.24
Ala-Gln	+++	0.81±0.04	+/−	0.20±0.03	+++	0.81±0.03	+++	0.56±0.29	+++	0.83±0.04	+++	0.55±0.30
Ala-Phe	++	0.49±0.01	+	0.10±0.01	++	0.50±0.06	++	0.24±0.14	+	0.67±0.01	++	0.27±0.16
Phe-Pro	+++	0.65±0.04	−	0.03±0.03	++	0.56±0.03	+++	0.13±0.08	++	0.60±0.04	+++	0.21±0.13
Phe-Val	++	0.39±0.10	+	0.19±0.05	++	0.39±0.05	++	0.27±0.06	+	0.58±0.13	++	0.31±0.09
Pro-Gly	+++	0.45±0.03	−	0.09±0.01	++	0.53±0.04	++	0.29±0.18	++	0.68±0.07	++	0.26±0.21
Pro-Leu	+++	0.30±0.02	−	0.06±0.03	++	0.21±0.03	++	0.11±0.05	+	0.70±0.03	+	0.10±0.01
Thr-Gln	+++	0.57±0.20	−	0.09±0.07	+++	0.56±0.02	+++	0.25±0.03	+++	0.78±0.01	+++	0.37±0.04
Gly-Gly-Gly	+++	0.14±0.05	−	0.03±0.02	−	0.08±0.02	+/−	0.11±0.04	−	0.07±0.05	+/−	0.11±0.04
NH4Cl		0.63±0.08		0.50±0.14		0.57±0.03		0.54±0.08		0.51±0.12		0.60±0.01

^a DppA5 was omitted since it showed a similar phenotype as the SBP penta mutant in the Biolog Phenotype MicroArrays.

^b Average respiratory activity of a strain in one well of the Biolog Phenotype MicroArray plates after 24 hours. −, <2000 (no respiratory activity); +/−, 2000–4000; +, 4000–6000; ++, 6000–8000; +++, >8000 (solid respiratory activity).

^c Optical densities were determined after 24 h of growth in Minimal Medium P supplemented with 2 mM of a di/tripeptide or NH₄Cl as sole nitrogen source.

^d Boldface numbers indicate a significant difference between the extent of respiratory activity in Biolog Phenotype MicroArray and the extent of growth in minimal medium supplemented with di/tripeptides as the sole nitrogen source.