# Screening of Plants and Indigenous Bacteria to Improve Arsenic Phytoextraction
## 3 Results and Discussion
### Microcosm Tests with Oxalate
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Soil**} & \multirow{2}{*}{**Treatment**} & \multicolumn{2}{c}{_Z. mays_} & \multicolumn{2}{c}{_C. sativa_} & \multicolumn{2}{c}{_B. juncea_} \\ \cline{3-8}  & & **Root** & **Shoot** & **Root** & **Shoot** & **Root** & **Shoot** \\ \hline \multirow{4}{*}{S2} & CT & 0.10 \(\pm\) 0.02a & 0.05 \(\pm\) 0.01a & 0.03 \(\pm\) 0.01a & 0.02 \(\pm\) 0.01a & 0.15 \(\pm\) 0.02a & 0.07 \(\pm\) 0.01a \\  & CT+ & 0.11 \(\pm\) 0.01a & 0.04 \(\pm\) 0.01a & 0.04 \(\pm\) 0.01a & 0.01 \(\pm\) 0.01a & 0.13 \(\pm\) 0.01a & 0.08 \(\pm\) 0.01a \\  & O & 4.24 \(\pm\) 0.34b & 2.08 \(\pm\) 0.10b & 5.10 \(\pm\) 0.61b & 3.96 \(\pm\) 0.20b & 10.5 \(\pm\) 0.95b & 5.06 \(\pm\) 0.30b \\  & O+ & 5.02 \(\pm\) 0.35b & 2.13 \(\pm\) 0.09b & 5.03 \(\pm\) 0.45b & 3.85 \(\pm\) 0.12b & 12.9 \(\pm\) 1.03b & 6.57 \(\pm\) 0.26c \\ \hline \multirow{4}{*}{SW} & CT & 0.07 \(\pm\) 0.01a & 0.04 \(\pm\) 0.01a & 0.03 \(\pm\) 0.01a & 0.01 \(\pm\) 0.01a & 0.18 \(\pm\) 0.02a & 0.11 \(\pm\) 0.01a \\  & CT+ & 0.06 \(\pm\) 0.01a & 0.04 \(\pm\) 0.01a & 0.02 \(\pm\) 0.01a & 0.02 \(\pm\) 0.01a & 0.16 \(\pm\) 0.01a & 0.11 \(\pm\) 0.01a \\ \cline{1-1}  & O & 6.07 \(\pm\) 0.55b & 3.19 \(\pm\) 0.16b & 5.32 \(\pm\) 0.48b & 2.54 \(\pm\) 0.15c & 3.87 \(\pm\) 0.43b & 4.03 \(\pm\) 0.28b \\ \cline{1-1}  & O+ & 13.2 \(\pm\) 0.53c & 5.22 \(\pm\) 0.21c & 4.96 \(\pm\) 0.40b & 1.98 \(\pm\) 0.08b & 4.42 \(\pm\) 0.31b & 4.97 \(\pm\) 0.25b \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Arsenic concentration (mg kg\({}^{-1}\)) in roots and shoots of _Z. mays, C. sativa_, and _B. juncea_ grown on soil control (CT) and As-contaminated soil treated with oxalate (O). The addition of PGPR bacteria (first set of isolates) is indicated with the “+” sign. Values are reported as mean (\(n=3\)) \(\pm\) SD. Values with different letters are significantly different at the 5% probability level (Tukey’s test). Figure 7: Arsenic total uptake by (**a**) roots and (**b**) shoots of _Z. mays, C. sativa_, and _B. juncea_ grown on soil control (CT) and As-contaminated soil treated with oxalate (O). The addition of PGPR bacteria (first set of isolates) is indicated with the “+” sign. Values are the mean of three replicates, and the error bars show the standard deviation. Values with different letters are significantly different at the 5% probability level (Tukey’s test). As regards the concentration of As absorbed by the plant species, the data in Table 5 confirm the trend of the previous tests, i.e., a significant increase in uptake following treatment with oxalate. Figure 9 shows the total removal of As by the plants considered in the third set of microcosms. On a more in-depth analysis, comparing the data in Tables 4 and 5, it appears clear that in the third microcosm set, the plants were able to adsorb larger quantities of As than in the second set of tests. This can reasonably be attributed to the different composition of the bacterial consortium. Figure 10 compares the total removals in the two different series of microcosms (second and third sets) performed using oxalate and the two different types of bacterial consortia. The data confirm what has already been observed in relation to soil S2 and the concentration of As in plants: there is an increase in the \"total uptake\" in the third growth compared to the second, both for corn and hemp. This difference does not appear as significant in the case of SW soil. Figure 9: Arsenic total uptake by (**a**) roots and (**b**) shoots of _Z. mays_ and C. _sativa_ grown on soil control (CT) and As-contaminated soil treated with oxalate (O). PGPR bacteria (second set of isolates) were added to all soil samples, as indicated by the “++” sign. The values are the mean of three replicates, and the error bars show the standard deviation. Values with different letters are significantly different at the 5% probability level (Tukey’s test).