peaked around 10 – 30 nM/OD600nm (Figures 3 and 4). Some bacterial strains, however, displayed much higher or lower ATP levels. For example, a clinical isolate of Acinetobacter junii (AJ4970) had a peak extracellular ATP level of > 250 nM/OD600nm, several fold higher than the peak concentrations observed in most bacterial strains (Table 5). In contrast a clinical isolate TGF-beta inhibitor of Klebsiella pneumoniae had a low peak ATP level of approximately 1 nM/OD600nm (Table 5). The extracellular ATP did not appear to display a species – specific pattern and strains from the same bacterial species could have very different peak ATP levels (e.g. AJ4970 at 255.2 ± 56.8 nM/OD600nm vs. AJ4978 at 17.0 ± 1.1 nM/OD600nm), suggesting that extracellular ATP is a common phenomenon to many bacterial species while the dynamics of ATP release is
different in each bacterial strain. Table 5 Extracellular ATP from various bacterial species Strain Species Peak hour Peak level (nM/OD) AJ4970 Acinetobacter junii 6 255.2 ± 56.8 AJ4978 Acinetobacter junii 6 17.0 ± 1.1 PA292 BI2536 Pseudomonas aeruginosa 6 25.5 ± 1.1 PA4553 Pseudomonas aeruginosa 3 20.5 ± 0.6 KP7690 Klebsiella pneumoniae 9 9.3 ± 0.5 KP2320 Klebsiella pneumoniae 9 1.0 ± 0.0 KO76 Klebsiella oxytoca 3 31.1 ± 4.0 SA25923 Staphylococus aureus 6 21.4 ± 3.5 MRSA43300 Staphylococus aureus 6 19.3 ± 1.3 Results are the average of three assays with standard deviations. The ATP levels of two isolates of Acinetobacter junii CB-839 AJ4970 and AJ4978 were analyzed in more details to compare the quantity of ATP in the culture supernatant to that in bacterial DNA ligase cells. Overnight culture of AJ4970 or AJ4978 was diluted 1:100 in fresh LB broth and cultured at 37°C with shaking. Aliquots were collected at various time points and the ATP levels in the culture supernatant and bacterial pellet were determined (Figure 7A
and B). The ratio of total ATP in the supernatant to that in the bacterial pellet from the same volume of bacterial culture was also determined (Figure 7C). The ATP level in the culture supernatant of AJ4970 reached a peak level of over 300 nM at 6 hours of incubation (Figure 7A) and the ratio of ATP in the culture supernatant to that in the pellet (total ATP in supernatant/total ATP in the pellet) peaked at 0.58 at 9 hours of incubation (Figure 7C). By comparison AJ4978 displayed much lower ATP levels in the culture supernatant as well as lower supernatant/pellet ratios of ATP (Figure 7A and C). The ATP levels in the bacterial cells were comparable in AJ4970 and AJ4978, except that AJ4978 had a higher intracellular ATP level at 3 hours of incubation (Figure 7B). Figure 7 ATP levels in the cultures of Acinetobacter junii . Overnight cultures of two clinical isolates of Acinetobacter junii AJ4970 and AJ4978 were diluted 1:100 in fresh LB broth and cultured at 37°C with shaking.