## 3 The Effect of Aquatic Macrophyytes on Microbial Organisms  
Electroactive bacteria (EAB), or exoelectrogens, are generally recognized as the group of microorganisms that feature an essential role in the performance of CWMFCs. These are bacteria capable of generating electrical energy by organic matter oxidation and moving the electrons produced to an acceptor outside their cells [14; 16; 38]. In CW-MFC, the presence of macrophytes generally plays a crucial role in enhancing the abundance and diversity of the microbial community in CWMFC and their subsequent effect on contaminant removal and bioelectricity generation [15; 37]. Their roots provide a vast surface area for microbial growth and attachment, allowing for the decomposition and uptake of pollutants from wastewater [39]. The efficiency of the system is primarily achieved by sustaining a high redox potential between the upper and lower segments of the CW-MFC. The involvement of aquatic macrophytes is one of the major components known to contribute to root oxygen and exudate secretion. Root oxygen released via plant root respiration, also known as radial oxygen loss (ROL), creates aerobic, anaerobic, and facultative aerobic conditions for various types of microorganisms. These conditions enhance the degradation of organic pollutants by facilitating microbial metabolism [40; 41; 42; 43; 44]. In addition, exudates consisting of carbohydrates, amino acids, and water-soluble sugar released by macrophte roots provide the required carbon source and energy for the microbial metabolism and growth around the rhizosphere of the aquatic macrophtye. This, however, results in a greater relative abundance of EABs, which are responsible for bioelectricity production [37; 41; 42]. A recent study was undertaken by [PERSON] et al. [45] to assess the influence of aquatic macrophytes on bioelectricity production, contaminant degradation, and micro bacterial community diversity in CWMFCs. The relative abundance of EABs (firmicutes and beta-proteobacteria) in  
Figure 2: Interaction between macrophytes and other physical components of CWMFC. planted CW-MFCs was substantially greater than that of unplanted CW-MFCs, according to the 165 rRNA microbial analysis of their study. These findings indicate that CWMFC with aquatic plants had a significant effect on the exoelectrogens' quantity around the anode material. Subsequently, the higher relative abundance of EABs in the planted CWMFC led to an increase in bioelectricity production of 8.91 mW\(\cdot\)m\({}^{-2}\) in CWMFC. On the other hand, the highest removal efficiency for COD and nitrate-nitrogen (NO\({}_{3}\)-N) was obtained in photosynthetic CW-MFC with smaller filler sizes of 86.7%, and 87.1%, respectively, which was strongly attributed to the diversity and relative abundance of microorganisms [45]. Similar to this study, [PERSON] et al. [40] performed high-throughput sequencing in their experimentation to assess the effect of different macrophytes and no-macrophyte CWMFC; _Canna indica_, _Acorus calamus_, _and Ipomoea aquatic_ on microbial diversity. According to the Shannon diversity indexes (H\({}^{\prime}\)) of their study, species richness and evenness were relatively higher in planted than unplanted: H\({}^{\prime}\) = 4.69. 4.94, 4.99, AND 5.01, respectively, for unplanted, _Canna indica_, _Acorus calamus_, and _Ipomoea aquatic_. More specifically, from the phylogenetic diversity of bacteria, the relative abundances of Geobacter (proteobacteria), the most well-known EAB in the anodes of the unplanted, _Canna indica_, _Acorus calamus_, and _Ipomoea aquatic_ systems, were 5.12%, 20.41%, 11.67%, and 20.74%, respectively. This result was noticed to have greatly influenced a higher electrical output and the removal efficiency in CWMFC planted with _Canna indica_ and _Ipomoea aquatic_ than those that were unplanted due to microbial diversity as a result of the plant root exudate and oxygen release. In earlier studies by [PERSON] et al.