## 3 Results
SL3R6, were found in internal plant tissues; all five strains were found inside roots and leaves, except for _P. migulae_ SVB3R4 which was unable to colonize leaves. In general, as reported in Table 3, the bacterial density (evaluated as CFU/g of root or shoot dry weight) was about \(1\times 10^{3}\). Figure 3: Screening of the physiological traits involved in plant growth promotion. (**A**) Phosphate solubilization on tricalcium phosphate (TCP) medium (bacterial growth indicates phosphate solubilizing activity); (**B**) siderophore synthesis on Chrome Azurol S (CAS) agar (orange halo); (**C**) IAA production (pink halo); (**D**) tolerance to salt stress evaluated as minimal inhibitory concentration (MIC) showing the tolerance of bacterial strains to specific molecules. The well was considered positive when the presence of a bacterial cell pellet was observed; (**E**) 1-aminocyclopropane-1-carboxylate (ACC) deaminase synthesis (brown/black color development). \begin{table}
\begin{tabular}{l c c c c c c c c} \hline \hline  & _H. Institamm_ & _S.rhizophila_ & _P. migulae_ & _P. migulae_ & _P. migulae_ & _P. migulae_ & _Personomonas_ sp._ & _P. brassicecaram_ & _Pseudomonas_ sp._ \\  & **CVB2R5** & **CVB355** & **SVB3R2** & **SVB3R3** & **SVB3R4** & **SVB3R5** & **SVB6R1** & **SL3R6** \\ \hline \multicolumn{1}{c}{Cefrazidine 30 mg} & S & S & S & S & S & S & S \\ \hline \multicolumn{1}{c}{Cotiromoxazole 25 mg} & S & S & S & S & S & S & S \\ \hline \multicolumn{1}{c}{Certaincin 10 ug} & S & S & S & S & S & S & S \\ \hline \multicolumn{1}{c}{Ciprofloxacinsoian 5 ug} & S & S & S & S & S & S & S \\ \hline \multicolumn{1}{c}{Nalidistic acid 30 ug} & S & S & S & S & S & S & S \\ \hline \multicolumn{1}{c}{Nitroturns 100 ug} & R & R & R & R & R & R & R \\ \hline \multicolumn{1}{c}{Cefoperazone30 ug} & S & R & S & S & S & S & S \\ \hline \multicolumn{1}{c}{Phosphomycin 50 ug} & R & S & S & S & S & S & S \\ \hline \multicolumn{1}{c}{Cefixune 10 ug} & S & R & S & S & S & S & R & S \\ \hline \multicolumn{1}{c}{Norfloxacin 10 ug} & S & S & S & S & S & S & S \\ \hline \end{tabular}
\end{table} 
Table 2: Sensitivity (S) or resistance (R) of eight selected bacterial endophytes to different antibiotics. According to the ability of the isolated strains to colonize plant tissues after inoculation, we selected five strains (_P. migulae_ SVB3R2, _P. migulae_ SVB3R3, _P. migulae_ SVB3R4, _Pseudomonas_ sp. SVB3R5 and _P brassicacearum_ SVB6R1) as true bacterial endophytes and used them for further experiments. All five strains increased plant and root biomass compared to uninoculated plants (Figure 4A,B). _P. migulae_ SVB3R3 and _P. brassicacearum_ SVB6R1 were the most effective, increasing the weight of whole plants by 54.5% and 53.9%, respectively and root weight by 62.5% and 65.9%, respectively. Shoot fresh weight was higher in plants treated with _P. migulae_ SVB3R2 (+37.4%) and SVB3R3 (+43.3%) (Figure 4C), while all strains except SV6R1 enhanced the number of leaves (Figure 4D) compared to controls. Three of the selected strains, _P. brassicacearum_ SVB6R1, _P. migulae_ SVB3R3 and _P. migulae_ SVB3R4, were resistant to inhibition by 7.2% salt; the MIC values for _P. migulae_ SVB3R2 and _Pseudomonas_ sp. SVB3R5 were 5.4% and 6.2%, respectively. Therefore, the salt tolerance conferred by bacterial strains was largely above the salt concentration applied for plant treatment. Figure 4: Effects of the selected bacterial strains on sorghum growth parameters (plant fresh weight, (**A**); root fresh weight, (**B**); shoot fresh weight, (**C**); and leaf number, (**D**)). The values presented in the figures are means \(\pm\) standard errors (\(u=10\)). Bars topped by the same letter do not differ significantly at \(p<0.05\) by one-way ANOVA followed by [PERSON]’s post hoc test. Bars topped by \({}^{*}\) are significant at \(p<0.05\) by one-way ANOVA followed by [PERSON]’s post hoc test compared to uninoculated control plants. Plant treatments: uninoculated plants (C), Plants inoculated by _P. migulae_ SVB3R2 (SVB3R2), _P. migulae_ SVB3R3 (SVB3R3), _P.