environmental remediation involves manipulating the genomes of specific microbes to increase their metabolic power. for example, in pseudomonas putida, scientists have engineered a strain to overexpress glc and glcdef, operons that contain genes coding for enzymes that convert toxic intermediates into the next substrates in the pathway. this would allow plastic monomers such as ethylene glycol to be converted into high-value chemicals such as medium-chain-length polyhydroxyalkanoates (mcl-pha). as a natural bioplastic, phas have similar properties to synthetic plastics and are biodegradable as well as nontoxic making them useful for biomedical applications. its utility even extends to its potential for the production of hydrocarbon jet fuel if further chemically catalyzed. genetically engineered bacteria also do not have a practical application in the ocean, yet, according to the ocean conservatory group. dr. naryan believes that releasing genetically engineered bacteria into the ocean ecosystems could be irresponsible and have many negative side effects on the ecosystem. as the ocean conservatory group states, the solution to the plastic problem does not lie in genetically engineered bacteria, but rather decreasing the plastic input into the ocean and increasing collection and recycling efforts. with these potential limitations in mind, a deeper comparison of the pros and cons of engineering microbes for plastic degradation should be conducted. as mentioned, one problem in environmental remediation of plastics is that only 30% of plastics are collected to be recycled. without efficient collection in the first place, the high energy cost of enzymatic recycling would be more burdening than the amount of waste it would break down. another problem includes the fact that this may not be applicable at a wide scale since enzymes have a short half-life so engineered organisms may not remain catalytically active for long enough to be effective. on the other hand, to fix unpredictable enzyme-polymer interactions, there has been development of new techniques such as computational tools to visualize the 3-d interactions between plastics and enzymes. thus, engineered microbes can remain as a hopeful solution for plastic remediation. figure 4: this diagram demonstrates the effect of toxic material in marine environments and the potential for biomagnification. it is hypothesized that plastic degradation constituents could alleviate biomagnification effects. toxicity of degradation products a study was performed to understand the toxicity of the degradation of polythene bags and cups by p. aeruginosa, streptomyces sp., aspergillus niger, staphylococcus aureus, and rhizopus sp. the study found carbon dioxide gas to be the main byproduct of the degradation process of polythene by the bacteria mentioned before. however, the particles produced as a byproduct of pe bio-degradation had negative impacts on the production of polysaccharides, proteins, and nutrient uptake in roots of plants. another study performed by aswale focused on how biodegraded polythene affected seed germination in plants. it found that biodegraded polythene was correlated with a decrease in percentage of seed germination, indicating that the byproducts of the breakdown could have negative effects on the seed health. food web biomagnification as seen in figure 4, food web biomagnification refers to the process by which concentrations of contaminants increase as the trophic levels increase. in terms of plastic, this means when plankton eat plastic, then fish eat the plankton, and larger fish eat that fish, the amount of plastic accumulates in the largest fish. therefore, removing plastic from the system at the bacteria level would prevent the plastic from bioaccumulating in larger fish. however, as mentioned above, these bacteria are not very efficient at degrading plastic, and therefore do not have the capabilities to create a substantial impact on this problem.