## 3 Results
### Salt and Temperature Tolerance, and PGP Features  
The 13 NaCl resistant bacterial strains showed a clear different capability to tolerate this salt, ranging from 2.0 M up to 4.0 M (Table 4), as in the case of two strains of _Staphylococcus succinus_ (MD6 and MB8) able to tolerate 4.0 M NaCl, or _Brevibacterium_ (strain 128293) able to grow in the presence of 3.5 M NaCl. All the bacterial strains had the optimal growth temperature at 37 \({}^{\circ}\)C except _Bacillus stratospheric_, which had its optimal growth temperature at 45 \({}^{\circ}\)C, but it was also able to grow at 55 \({}^{\circ}\)C.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Strain**} & \multirow{2}{*}{**Closest Relative Strains**} & **Cover (\%)** & **Identity (\%)** & **2 M** & **2.5 M** & **3 M** & **3.5 M** & **4 M** & **27 \({}^{\circ}\)C** & **37 \({}^{\circ}\)C** & **45 \({}^{\circ}\)C** & **55 \({}^{\circ}\)C** \\ \hline MD6 & _Staphylococcus succinus_ strain JM40 & 100 & 99.53 & ++ & +++ & ++ & ++ & + & + & + & ++ & + & - \\ \hline QR21 & _Bacillus licheniformis_ strain hswx145 & 91 & 97.25 & +++ & ++ & ++ & - & - & + & +++ & - & - \\ \hline MA1 & _Bacillus halotelreams_ strain HEPRR26 & 100 & 100 & +++ & ++ & ++ & - & - & + & +++ & - & - \\ \hline QH11 & _Halomonas_ sp. KO116 & 100 & 99.44 & +++ & ++ & ++ & + & - & + & +++ & - & - \\ \hline QB13 & _Bacillus stratospheric_ strain MP-R2a & 100 & 100 & +++ & +++ & + & - & + & ++ & ++ & ++ \\ \hline QH8 & _Halomonas alkalaturatexia_ strain BR04 & 100 & 99.77 & +++ & ++ & ++ & + & - & + & +++ & - & - \\ \hline MB8 & _Staphylococcus succinus_ strain NC2 & 100 & 98.83 & +++ & +++ & ++ & ++ & + & NA & NA & NA \\ \hline QA10 & _Brevibacterium_ sp. strain 128293 & 86 & 96.32 & +++ & ++ & ++ & - & + & NA & NA & NA \\ \hline QH20 & _Halomonas_ sp. MS6-1 & 98 & 96.56 & +++ & ++ & ++ & + & - & + & NA & NA & NA \\ \hline QB12 & _Bacillus majorensis_ strain X9 & 100 & 100 & +++ & ++ & ++ & + & - & + & NA & NA & NA \\ \hline QH15 & _Halomonas_ sp. MS6-1 & 100 & 99.56 & +++ & ++ & ++ & + & - & + & NA & NA & NA \\ \hline QH16 & _Halomonas_ sp. MS6-1 & 100 & 99.56 & +++ & ++ & ++ & + & - & + & NA & NA & NA \\ \hline MQ11 & _Brevibacterium_ sp. strain SLs05 & 100 & 99.67 & +++ & ++ & ++ & + & - & + & NA & NA & NA \\ \hline \hline \end{tabular}  
* + ++, +++ indicate low, moderate or high growth, respectively. NA = Not Available. (A short description of the bacterial species has given in Note SM2).  
\end{table}
Table 4: Growth of NaCl resistant bacterial strains, identified by 16S rDNA sequencing, at difference sodium chloride concentration and different temperature.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Bacterial Pellet** & **Medium** & **Number of Colonies** \\ \hline Quinoa 300 mM & PCA & 93-10\({}^{4}\)\(\pm\) 93 \\ \hline Quinoa 300 mM & PCA + 500 mM & 37-10\({}^{3}\)\(\pm\) 110 \\ \hline Maize 150 mM & PCA & 22-10\({}^{4}\)\(\pm\) 47 \\ \hline Maize 150 mM & PCA + 500 mM & 31-10\({}^{3}\)\(\pm\) 83 \\ \hline \hline \end{tabular}  
Based on morphological differences a total of 50 bacterial colonies underwent NaCl selection as described in the Section 2. Among the 50 initially isolated colonies, resistant to 500 mM NaCl both from maize (25) and quinoa (25), only 13 colonies showed different degrees of resistance, as illustrated in Table 4.  
\end{table}
Table 3: Average CFU on control medium (PCA) and on PCA added with salt (PCA + 500 mM) related to the bacteria pellets obtained by quinoa or maize plants irrigated with 300 or 150 mM NaCl solutions, respectively.  
The selected bacterial strains were also characterized by different and peculiar PGP features (ammonia, siderophore and IAA production or capacity to metabolize tricalcium phosphate). Among these strains, six showed PGP features (Table 5), whilst the others did not (data not shown). However, only two strains distinguish themselves for showing, contemporaneously, all four PGP features, namely: _Staphylococcus succinus_ (strain JM40) and _Bacillus stratosphericus_ (strain MPF-B2a).