# Strategies for Enhancing Extracellular Electron Transfer in Environmental Biotechnology: A Review
## 3 Strategies for Enhancing EET in Environmental Biotechnology
### Integrated Strategies for Enhancing EET
Furthermore, genetic programming (GP) is an additional technique that makes it possible to optimize the AI model's structure by minimizing errors through the use of algorithms like cross-validation and the Kennard-Stone algorithm [110]. To incorporate novel components into bacterial cells, one can use the de novo protein design technique. The assembly of peptides into protein structure is connected to the design architecture of de novo and the bundling of \(\alpha\)-helices into metal-binding proteins is one way to accomplish this. Short gene fragments are integrated into the genes of _E. coli_ in bacterial surface display systems and LamB, OmpA, Lpp-OmpA, and PhoE coli OM proteins coordinate protein integration into the outer membrane cells [112]. Similarly, genetically modifying _E. coli_ was used to facilitate EET by introducing a biosynthetic pathway for _Pseudomonas_ phenazine-1-carboxylic acid [113]. The findings of the study demonstrated that the implementation of this electrochemical system resulted in a notable augmentation in the synthesis of phenazine-1-carboxylic acid, consequently improving the EET efficiency of MFCs. Another versatile algorithm for flexible diagnosis and control is fuzzy logic (FL). This technique is capable of observing data and forecasting system outputs logically. FL is frequently used as an intermediate step to streamline data processing and lessen the negative impact on model accuracy [114]. * Hybrid Systems: The hybrid technique is another system which integrates two treatment systems, resulting in the enhanced performance efficiency of the overall system. It was noted that the implementation of a constructed wetland (CW)-MFC containing activated carbon granules and manganese ore can enhance the biochemical processes involved in N-transformations in the absence of oxygen [115]. The plant-microbial fuel cell (Plant-MFC) is also an emerging technology that can effectively harness solar energy to generate bioelectricity through the symbiotic link between plants and microorganisms in the rhizosphere region. Table 1 shows the different plants that have been utilized in Plant-MFCs and the maximum power density obtained in the different scenarios. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Reactor Configuration** & **Plant** & **Maximum Power Generated** & **Ref.** \\ \hline Plant–MFC & _Glyceria maxima_ & 67 mW/m\({}^{2}\) & [116] \\ Plant–MFC & _O. sativa_ & 330 mW/m\({}^{2}\) & [117] \\ Plant–MFC & _S. partita anglica_ & 100 mW/m\({}^{2}\) & [118] \\ Plant–MFC & _S. anglica_ & 222 mW/m\({}^{2}\) & [119] \\ Plant–MFC & _Arundinella anomalous_ & 222 mW/m\({}^{2}\) & [119] \\ Plant–MFC & _Edinorria crassipes_ & 224.93 mA/m\({}^{2}\) & [120] \\ Plant–MFC & _Pennisetum setacum_ & 8.84 mW/m\({}^{2}\) & [121] \\ Plant–MFC & _Ipomoea aquatic_ & 105 mA/m\({}^{2}\) & [122] \\ Plant–MFC & _Cyperus involucratus_ & 5.99 mW/m\({}^{2}\) & [123] \\ Plant–MFC & _S. anglica_ & 240 mW/m\({}^{2}\) & [124] \\ Plant–MFC & _Typha latifolia_ & 6.12 mW/m\({}^{2}\) & [125] \\ Plant–MFC & _O. sativa_ & 140 mW/m\({}^{2}\) & [126] \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Power density obtained in different plant–microbial fuel cells. Figure 5: Three distinct additive manufacturing processes are employed in the fabrication process of revolutionary microbial fuel cells (MFCs). (**a**) In Selective Laser Melting (SLM) technology the 3D object which is to be fabricated is divided into layers of a predetermined thickness of 30 μm and thereafter, transferred to the SLM machine. The process begins with the application of a layer of powdered material onto the building platform and the powders are fully melted along the designated path corresponding to the initial section of the component. The substrate platform thereafter undergoes a reduction in layer thickness along the z-axis, followed by the application of a new coating, and this iterative process continues until the whole part is complete.