Table 1.
Oligonucleotides used for the analysis by RT-PCR and RT-qPCR.
Table 2.
BSR of P. putida KT2440 cells subjected to air desiccation in the presence or absence of protectors (200 mM).
Fig 1.
Bacterial survival ratio (A) and log CFU/mL (B) of P. putida KT2440 under desiccation stress (30°C and 50% RH). DABD means days after the beginning of desiccation.
Fig 2.
Fluorescence micrographs of P. putida KT2440 cells treated with the LIVE/DEAD BacLight Bacterial Viability Kit.
(A) Bacterial cells before desiccation with trehalose (200 mM). (B) Bacterial cells before desiccation without a protector. (C) Bacterial cells protected with trehalose at 18 DABD. (D) Bacterial cells without a protector at 18 DABD. (E) Bacterial cells protected with trehalose adhered to germinated seeds after rehydration. (F) Bacterial cells without protection adhered to germinated seeds after rehydration. The samples were observed at 100×. Each image represents the MERGE of two captured images (green and red cells). The generation of MERGE images is shown in S1 and S3 Figs, and examples of MERGE cell analysis are shown in S2 and S4 Figs.
Fig 3.
Rhizosphere colonization by P. putida KT2440.
(A) Cell abundance from plants inoculated with rehydrated 18 DABD cells without protection in comparison to cell abundance from plants inoculated with rehydrated DABD cells in the presence of trehalose (200 mM). (B and C) Fluorescence micrographs of P. putida KT2440 using the LIVE/DEAD BacLight Bacterial Viability Kit. The samples were observed at 100×. (B) Cells obtained from the rhizosphere of plants inoculated with rehydrated 18 DABD cells without protection. (C) Bacterial cells obtained from the rhizosphere of plants inoculated with rehydrated 18 DABD cells in the presence of trehalose (200 mM). Each image represents the MERGE of two captured images (green and red cells). The generation of MERGE images is shown in S1D and S3D Figs, and examples of the analysis of cells in MERGE images are shown in S2D and S4D Figs.
Fig 4.
Mean fluorescence intensity (MFI) of P. putida KT2440 cells with protection (trehalose 200 mM).
(A) Analysis of SYTO 9 and (B) analysis of propidium iodide. (1) Samples obtained from the bacterial suspension before desiccation, (2) cells at 18 DABD rehydrated for 20 min, (3) cells adhered to maize sprouts, and (4) cells from rhizosphere colonization.
Fig 5.
Mean fluorescence intensity (MFI) of P. putida KT2440 cells without protection.
(A) Analysis of SYTO 9 and (B) analysis of propidium iodide. (1) Samples obtained from the bacterial suspension before desiccation, (2) cells at 18 DABD rehydrated for 20 min, (3) cells adhered to maize sprouts, and (4) cells from rhizosphere colonization.
Fig 6.
Bacterial behavior of P. putida KT2440 cells rehydrated with water (orange line) or in the presence of root exudates (blue line) under static conditions for 48 h.
Table 3.
Number of cells of P. putida KT2440 (log CFU/mL) 18 DABD and rehydrated with root exudates of maize.
Fig 7.
Fluorescence of P. putida KT2440 cells desiccated for 18 days and stained with the LIVE/DEAD BacLight Bacterial Viability Kit.
(A) Cells before desiccation and (B) 3, (C) 6, (D) 9, (E) 12, (F) 15, and (G) 18 DABD. Each image represents the MERGE of two captured images (green and red cells). The samples were observed at 100×. The generation of MERGE images is shown in S5 Fig, and examples of the analysis of MERGE images are shown in S6 Fig. (H) The BSR of P. putida KT2440 during desiccation.
Fig 8.
Mean fluorescence intensity (MFI) of the same images as in Fig 7.
(A) Analysis of SYTO 9. (B) Analysis of propidium iodide.
Fig 9.
Fluorescence of P. putida KT2440 cells desiccated for 18 days and stained with the LIVE/DEAD BacLight Bacterial Viability Kit.
(A) Cells before desiccation, (B) cells at 18 DABD rehydrated for 20 min, (C) cells at 18 DABD rehydrated for 24 h, (D) cells at 18 DABD rehydrated for 48 h. The samples were observed at 100×. Each image represents the MERGE of two captured images (green and red cells). Generation of MERGE images is shown in S7 Fig, and examples of analysis of MERGE images are shown in S8 Fig.
Fig 10.
Mean fluorescence intensity (MFI) of the same images as in Fig 9.
(A) Analysis of SYTO 9. (B) Analysis of propidium iodide.
Fig 11.
Transmission electron microscopy of P. putida KT2440.
(A) Before desiccation, 50,000×, (B) at 6 DABD, 30,000×, (C) at 12 DABD, 30,000× and (D) at 18 DABD, 50,000×.
Fig 12.
Fluorescence of P. putida KT2440 tagged with GFP desiccated for 18 days.
(A) Cells before desiccation and (B) 3, (C) 6, (D) 9, (E) 12, (F) 15, and (G) 18 DABD. The samples were observed at 100×. (H) The BSR of P. putida tagged with GFP during desiccation (blue line) and fluorescence intensity of P. putida tagged with GFP during desiccation (orange line).
Fig 13.
Gene expression levels of mutL (blue bar), mutS (orange bar) and oprH (gray bar) obtained by RT-qPCR. Before desiccation (0) and 6, 12 and 18 DABD.