**8. Conclusions**

Microbes, bacteria and algae are the major components of epiphytic microbes, which colonize the lower surface of floating plants. Bacterial biofilm has a crucial role in the removal of organics, inorganics and metals in FTW systems. The plant species and pollutant concentration in wastewater influence the nature and diversity of bacteria. Furthermore, the availability of nutrients influences the metabolism of bacteria and the pollutant removal efficiency. The rhizosphere and endophytes both have a prominent role in the pollutant removal process. The rhizospheric bacteria mostly remove the pollutants near the root system, whereas the endophytes mostly remove the pollutants inside the roots and shoots. The rhizospheric and endophytic bacterial community also enhances the pollutant removal process by alleviating the pollutant stress, increasing tolerance towards environmental changes, and regulating plant growth by direct and indirect mechanisms. The inoculation of plant roots with specific strains of bacteria also boosts the pollutant removal process.

It is clear from this information that plant–microbe interaction is vital for the pollutant removal process in FTWs. There is a need to conduct further research to gain a better understanding of specific microbe and plant interactions and their beneficial role in the pollutant removal process in the aquatic ecosystem. Environmental factors such as temperature, pH, and the availability of nutrients have a profound effect on the pollutant removal abilities of microorganisms. These factors need further investigation to achieve the optimal performance of microorganisms in FTWs. The nature of pollutants affects the persistence and survival of bacteria and may determine the type of bacterial communities in a wetland system. Bacteria specific to the removal of particular types of pollutants need to be identified and isolated for their future application in FTWs. Bacteria that are easy to culture in the lab with minimal prerequisites, which possess the potential to treat a diverse range of pollutants and can be augmented with diverse macrophytes in FTWs, need to be widely explored for their use in FTWs.

**Author Contributions:** The paper was written by M.J.S., S.A., N.N. and M.A. The data were collected and coordinated by A.A.A., F.K. and M.H.S. The paper was reviewed and revised by M.R., B.A., and M.A. All authors have read and agreed to the published version of the manuscript.

**Funding:** The authors are grateful to the Higher Education Commission (HEC) Islamabad, Pakistan, for its support.

**Acknowledgments:** The authors are grateful to the Higher Education Commission (HEC) Islamabad, Pakistan, for its support.

**Conflicts of Interest:** The authors declare no conflict of interest.
