# Harnessing Biotechnology for the Remediation of Organic Pollutants in Coastal Marine Ecosystems
## 4 Biotechnological Methods for Remediation
### Phytoremediation Approaches  
Phytoremediation refers to a mitigation technique in which plants, along with their associated soil microorganisms, carry out remediation of pollutant substances in order to reduce the toxic effects or concentration of the pollutants in the environment [63]. This technique utilizes plants to remediate contaminated media, including soil and water. It is favorable to the economy and environment as it utilizes green plants to absorb, accumulate, degrade, suppress, detoxify, or transform pollutants from contaminated soil and water [64, 65]. Phytoremediation is a promising soil remediation technique as it has gained significant attention from various sectors due to how cost-effective, efficient and eco-friendly it is [66]. This method fits well into coastal ecosystems, where multifunctional vegetation, such as mangroves, seagrasses, and algae, play an important role [63]. The mechanisms underlying phytoremediation include the following:  
* Phytoextraction  
Phytoextraction involves the absorption and accumulation of pollutants through the roots and their translocation to harvestable above-ground parts of the plants like the \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Pollutant** & **Representative** & **Peripheral Metabolic** & **Central Metabolic** & **References** \\ \hline Antibiotics & _Pseudomonas_ spp., _Bacillus_ spp., _Acinetobacter_ spp., _Streptomyces_ spp. & Hydrolysis, oxidation, & Tricarboxylic acid (TCA) cycle & [57] \\ \hline Polychlorinated & _Burkholderia xenovorans_, _Pseudomonas putida_, & Biphenyl degradation & \(\beta\)-ketoadipate & \\ Biphenyls (PCBs) & _Pseudomonas putida_, _Rhodococcus_ spp. & (dioxygenase-mediated oxidation to chlorobenzene) & pathway, TCA cycle & [58, 59] \\ \hline Polycyclic Aromatic & _Mycobacterium vanbaelnii_, _Spingomonas_ spp., (PAHs) & Dioxygenase-mediated & \(\beta\)-ketoadipate & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Representative microorganisms and metabolic pathways involved in bioremediation. leaves, stems and fruits [66; 67]. This process is generally effective for removing both heavy metals and certain organic compounds from water and sediments. Aquatic plants such as water hyacinth (_Eichhorria crassipes_), duckweed (_Lenna validiviana_ and _Spirodela polyrhiza_) and water lettuce (_Pistia stratites_) are known for their high biomass and ability to accumulate heavy metals and degrade organic pollutants in eutrophic and contaminated coastal waters [68; 69; 70]. The plants involved in phytoextraction can be used for other purposes like biofuel production or livestock feed, provided the toxins accumulated are safe [71]. Phytodegradation (Plytotransformation)  
Phytodegradation refers to the breakdown of contaminants within plant tissues through metabolic processes or by rhizospheric microbial communities [65]. Plant release enzymes such as peroxididases dehalogenases and lacases play a critical role in converting toxic substances into less harmful metabolites. Degradation of contaminants in the rhizosphere is known as rhizodegradation [72]. Pesticides are one type of organic pollutants that can be remediated through degradation or transformation by various plant parts. Plant parts can play a crucial role directly or indirectly in the phytodegradation process: in the direct process, plants absorb the contaminants, break them down into less harmful compounds, and distribute them within plant tissue [72]. This process is particularly beneficial for treating xenobiotic compounds like pesticides, polycyclic aromatic hydrocarbons (PAHs), and trichloroethylene.