Figure 3.

Legionella pneumophila thermal profile and culturability assay. (A) Bacterial cells were heat shocked at 40–55°C for 10 min and analyzed using flow cytometry. (B) Sorted cell fractions cultured on BCYE agar. Thermal shock at 50°C for 10 min transformed TO-stained injured cells into VBNC Legionella, as indicated by the lack of growth on the BCYE agar. (C) Pure culture of L. pneumophila subjected to 55°C thermal treatment in increments from 0 to 10 min. The population of VBNC L. pneumophila increased gradually with time 9% at 1 min, 20% at 3 min and then decreased to 5% at 5 min.