## 3 Results and Discussion
### Abundance of Antibiotic Resistance Genes
They observed that microalgal cells (i) absorbed and endocytosed the exogenous plasmids carrying _su1_, with no affection of the microalgae cell nucleus, (ii) EPS promoted and increased the adsorption of exogenous ARG-containing plasmids, and  
Figure 8: The abundance of the 16S rRNA, _intl1_, and antibiotic resistance genes (_su1_ and _bla_TEM) detected in each PBR: \(\blacksquare\) CV (C. _vulgaris_ + UWW); \(\blacksquare\) C+ (_C. vulgaris_ + autoclaved UWW); and \(\blacksquare\) C\(-\) (raw UWW), at the beginning of the experiment (full colored bars) and after 9 d of treatment (striped bars). Results (average \(\pm\) standard deviation) are expressed in a log (gene copy number 100 mL\({}^{-1}\)). Bars of the same gene with the same letters are not statistically different (two-way ANOVA followed by Tukey post hoc test \(p\) < 0.05). (iii) endocytosis increased with a larger time (more than 6 d) of contact between microalgae and plasmids [24]. This study [24] was performed in synthetic media instead of WW, with a controlled microbial population, and with the different operating conditions of temperature (30 \({}^{\circ}\)C), light exposure (120 \(\upmu\)mol m\({}^{-2}\) s\({}^{-1}\)), and cultivation time (10 d). However, in a real scenario using real WW, there are no guarantees that the same mechanisms may occur straightforwardly due to the complexity of WW composition, and the unlikeliness of the occurrence of intact plasmids in the environment. Nevertheless, the capacity of microalgae to adsorb extracellular DNA fragments containing ARGs should be studied in the future. Due to the promising results of AMS in the C\(-\) PBR, the treated water was tested for its stability in terms of 16S rRNA, \(intl1\), and ARG content (Figure 9), envisioning a possible treated water reutilization scenario. Storage revealed a decrease of 16S rRNA abundance (Figure 9A), as well as a reduction of \(intl1\), \(su1\), and \(bla_{\text{TEM}}\) abundance, with log reductions of 1.0, 0.7, and 2.5, respectively, when compared to values obtained at the end of the experiment (T9), corresponding to an RRG of 97.1, 94.2 and 99.9% from the beginning of the assay (T0) up to the end of the storage period (ST5d). Microalgae surface adsorbed bacteria co-precipitation might have had a role in this reduction, probably by a reconfiguration of the bulk water microbial composition [14]. \begin{table}
\begin{tabular}{c c c c c c c c} \hline  & \multicolumn{2}{c}{\(intl1\)} & \multicolumn{2}{c}{\(su1\)} & \multicolumn{2}{c}{\(bla_{\text{TEM}}\)} & \\
**PBR** & \multicolumn{2}{c}{**Prevalence**} & \multicolumn{2}{c}{**RRG (\%)**} & \multicolumn{2}{c}{**Prevalence**} & \multicolumn{2}{c}{**RRG (\%)**} & \multicolumn{2}{c}{**Prevalence**} & \multicolumn{2}{c}{**RRG (\%)**} \\  & **T0** & **T9** & & **T0** & **T9** & & **T0** & **T9** & \\ \hline \multirow{2}{*}{CV} & (1.5 \(\pm\) 0.1) & (2.0 \(\pm\) 0.1) & \multirow{2}{*}{\(-40.0\pm 6.1\) a} & (3.0 \(\pm\) 0.1) & (2.3 \(\pm\) 0.1) & (2.2 \(\pm\) 0.1) & (4.0 \(\pm\) 0.3) & \\  & & \(\times\) 10\({}^{-3.3}\) a & \(\times\) 10\({}^{-3.3}\) a & & \(\times\) 10\({}^{-2.3}\) a & & \(\times\) 10\({}^{-4.3}\) & \(\times\) 10\({}^{-4.3}\) & \(\times\) 10\({}^{-4.3}\) \\ C+ & (2.2 \(\pm\) 1.0) & (4.0 \(\pm\) 1.5) & & (3.1 \(\pm\) 0.1) & (4.2 \(\pm\) 0.1) & & & (2.2 \(\pm\) 0.1) & \\  & & \(\times\) 10\({}^{-3.8}\) a & \(\times\) 10\({}^{-3.8}\) a & & \(\times\) 10\({}^{-3.3}\) a & \(\times\) 10\({}^{-2.4}\) & \(-422.6\pm 1135\) b & & \(\times\) 10\({}^{-6.5}\) & \(\times\) 10\({}^{-6.4}\) \\ C\(-\) & & (5.6 \(\pm\) 1.2) & (1.8 \(\pm\) 0.3) & & (3.9 \(\pm\) 0.1) & (1.3 \(\pm\) 0.1) & & (6.6 \(\pm\) 0.1) & (1.7 \(\pm\) 0.2) & \\  & & \(\times\) 10\({}^{-3.8}\) b & & \(\times\) 10\({}^{-3.4}\) c & & \(\times\) 10\({}^{-2.2}\) a & \(\times\) 10\({}^{-2.3}\) a & \(\times\) 10\({}^{-2.4}\) & \(\times\) 10\({}^{-4.3}\) & 75.7 \(\pm\) 1.6 c \\ \hline \end{tabular}
\end{table}