## 3 Results
### Molecular Characterization of Culturable Bacteria  
All five isolates were selected for their N-fixing capacity to create the SynCom and test its efficacy in promoting plant growth under nutrient limitation. For each morphotype, at least two independent colonies were characterized to the genus/species level, using the 16S rRNA gene as a DNA barcode (see Section 2 \"Materials and Methods\"). All strains exhibiting the same morphotype had identical 16S rRNA gene sequences. Sequence data of 16S fragments were used to generate a phylogenetic tree to evaluate the genetic relatedness among these bacteria and known species. All five morphotypes belonged to _Bacillusaceae_ and were affiliated with taxa belonging to three representative clades of this family: Subtilis  
\begin{table}
\begin{tabular}{c c c c c c c} \hline  & & & & **Colony Diameter (cm)** & & **PS \({}^{*}\)** & **NF** \\
**Site** & **Strain** & & & **NaCl (\%)** & & **PI** & **+/** \\  & & **0** & **5** & **7.5** & **10** & & \\ \hline MP & & & & & & \\  & 1 & 0.85 & 0.96 & \(-\) & \(-\) & 1.87 & \(-\) \\  & 2 & 0.91 & 0.87 & 0.74 & 0.74 & 1.50 & \(-\) \\  & **3** & **1.61** & **0.94** & \(-\) & \(-\) & \(-\) & **+** \\  & **4** & **1.11** & **0.92** & \(-\) & \(-\) & **1.60** & **+** \\  & 21 & 0.78 & 0.64 & 0.58 & 0.55 & 1.40 & \(-\) \\  & 22 & 0.77 & 0.77 & 0.63 & 0.51 & 1.88 & \(-\) \\  & 23 & 1.23 & 0.64 & \(-\) & \(-\) & \(-\) & \(-\) \\  & **24** & **0.74** & **0.57** & **0.66** & **0.51** & **1.48** & **+** \\ PP & & & & & & & \\  & 5 & 0.85 & 1.58 & 0.93 & 0.73 & 1.88 & \(-\) \\  & 6 & 1.18 & 1.24 & 1.01 & 0.68 & \(-\) & \(-\) \\  & 7 & 1.18 & 0.92 & 0.86 & 0.72 & \(-\) & \(-\) \\  & 8 & 1.11 & 1.07 & 0.90 & 0.64 & \(-\) & \(-\) \\  & 16 & 1.03 & 3.21 & 0.69 & 0.58 & \(-\) & \(-\) \\ G & & 17 & 0.95 & 0.67 & 0.58 & 0.47 & 1.54 & \(-\) \\  & 18 & 0.60 & 0.65 & 0.55 & 0.58 & \(-\) & \(-\) \\  & 19 & 0.73 & 0.74 & 0.74 & 0.52 & 2.00 & \(-\) \\  & 20 & 1.09 & 3.22 & 0.71 & 0.54 & \(-\) & \(-\) \\  & 29 & 1.14 & 0.75 & 0.60 & \(-\) & \(-\) & \(-\) \\  & **30** & **1.27** & **2.12** & **1.88** & \(-\) & \(-\) & **+** \\  & 31 & 0.60 & 0.81 & 0.71 & 0.62 & \(-\) & \(-\) \\  & 32 & 0.94 & 0.69 & 0.70 & 0.54 & 1.37 & \(-\) \\ M & & 33 & 0.76 & 0.65 & 0.62 & 0.68 & \(-\) & \(-\) \\  & **34** & **0.99** & **0.85** & **0.65** & **0.57** & **1.21** & **+** \\  & 35 & 0.76 & 0.75 & 0.60 & 0.59 & \(-\) & \(-\) \\  & 57 & 0.62 & 0.67 & 0.56 & 0.49 & \(-\) & \(-\) \\  & 58 & 0.71 & 0.92 & 0.61 & 0.61 & \(-\) & \(-\) \\  & 59 & 1.08 & 0.96 & 0.84 & 0.65 & 1.17 & \(-\) \\  & 60 & 0.86 & 0.70 & 0.64 & 0.61 & \(-\) & \(-\) \\ \hline \end{tabular} Strains MP3, MP4, MP24, G30, and M34 (in bold) have been selected for lettuce inoculation and identified. \({}^{*}\) Phosphate solubilization index.  
\end{table}
Table 1: Phenotypic characteristics of the strains isolated from the phyllosphere of _P. Lentiscus_ plants grown in a pure (PP) and a mixed plantation (MP), in garrigue (G) and an old mine (M), located in North Sardinia. The salt tolerance was tested on LBA amended with 0, 5, 7.5, and 10% NaCl, measuring the colony diameter. The phosphate-solubilizing activity (PS) was determined by calculating the phosphate solubilizing index (PI). The N-fixing (NF) ability was marked with a + symbol. The minus symbol (\(-\)) refers to the absence of growth (no colony formation).  
Clade (strains G30 and MP24), Cereus Clade (strain MP3), Megaterium Clade (strains MP4 and M34). The phylogenetic relationship between the isolates and the closely related taxa is shown in Figure 2.