{"id":{"repo_id":"woods-hole","oai_identifier":"oai:darchive.mblwhoilibrary.org:1912/73005"},"canonical_url":"https://search.dev.ndltd.org/etd/woods-hole/oai:darchive.mblwhoilibrary.org:1912/73005","repository":{"repo_id":"woods-hole","name":"Woods Hole Oceanographic Institute","base_url":"https://darchive.mblwhoilibrary.org/server/oai/request"},"display":{"title":"Bacterial interactions and enzyme kinetics in environmental polyester degradation","abstract":"Plastic waste accumulation in the environment is a global concern. With production of these materials projected to increase, strategies to enhance polymer degradability in natural systems are necessary to reduce their environmental accumulation. In this dissertation, the environmental biodegradation of copolyesters was explored to understand the biological processes that control the removal of these materials in natural systems. First, the role of microbial consortia over single organisms in the degradation of poly(butylene sebacate coterephthalate) (PBSeT, a biodegradable alternative to commodity plastics) was investigated. Using enrichment cultures from the Mediterranean Sea, a set of bacteria were isolated and their individual contributions toward polymer degradation assessed via coculture respiration assays, monoculture growth measurements, DOC accumulation and removal tracking, and quantification of specific polymer degradation products. The results show depolymerization was controlled by a bacterium that metabolized only one monomer component of the polymer, while downstream consumers were required to remove the other moieties of the polymer. Second, the influence of growth rate and substrate preference on the success of degrader-consumer pairs was explored using two bacteria isolated from the previous PBSeT enrichment experiments. Monoculture Monod kinetics on the monomers of the polymer revealed each bacterium’s preference and competitiveness for PBSeT substrates. Subsequently, coculture incubations with the whole plastic revealed how these dynamics manifest in complex systems. Informed by measured kinetic parameters, modelling was then utilized to demonstrate the influence of changing consumer growth rates on the success of the pair. The results demonstrated that growth rate, and not just metabolic capability, dictated which part of the polymer was consumed and by which bacterium. Third, the effect of cutinase adsorption to plastic surfaces on the distribution of dissolved degradation products during enzymatic depolymerization was explored. Using a commercial cutinase from the organism Humicola insolens, conventional and inverse Michaelis-Menten kinetics were employed to extract catalytic turnover rates and attack-site densities. Additionally, specific oligomeric products were quantified and tracked over time. These results illustrated that when the enzyme-to-plastic ratio exceeded the attack site density, larger oligomers were broken down in the solution phase, whereas enzyme-to-plastic ratios below the attack site density correlated with accumulation of those same compounds. This dissertation addresses gaps in the fundamental understanding of microbial consortia degradation of polyesters and the related role of heterogenous catalysis in enzymatic depolymerization.","abstract_html":"Plastic waste accumulation in the environment is a global concern. With production of these materials projected to increase, strategies to enhance polymer degradability in natural systems are necessary to reduce their environmental accumulation. In this dissertation, the environmental biodegradation of copolyesters was explored to understand the biological processes that control the removal of these materials in natural systems. First, the role of microbial consortia over single organisms in the degradation of poly(butylene sebacate coterephthalate) (PBSeT, a biodegradable alternative to commodity plastics) was investigated. Using enrichment cultures from the Mediterranean Sea, a set of bacteria were isolated and their individual contributions toward polymer degradation assessed via coculture respiration assays, monoculture growth measurements, DOC accumulation and removal tracking, and quantification of specific polymer degradation products. The results show depolymerization was controlled by a bacterium that metabolized only one monomer component of the polymer, while downstream consumers were required to remove the other moieties of the polymer. Second, the influence of growth rate and substrate preference on the success of degrader-consumer pairs was explored using two bacteria isolated from the previous PBSeT enrichment experiments. Monoculture Monod kinetics on the monomers of the polymer revealed each bacterium’s preference and competitiveness for PBSeT substrates. Subsequently, coculture incubations with the whole plastic revealed how these dynamics manifest in complex systems. Informed by measured kinetic parameters, modelling was then utilized to demonstrate the influence of changing consumer growth rates on the success of the pair. The results demonstrated that growth rate, and not just metabolic capability, dictated which part of the polymer was consumed and by which bacterium. Third, the effect of cutinase adsorption to plastic surfaces on the distribution of dissolved degradation products during enzymatic depolymerization was explored. Using a commercial cutinase from the organism Humicola insolens, conventional and inverse Michaelis-Menten kinetics were employed to extract catalytic turnover rates and attack-site densities. Additionally, specific oligomeric products were quantified and tracked over time. These results illustrated that when the enzyme-to-plastic ratio exceeded the attack site density, larger oligomers were broken down in the solution phase, whereas enzyme-to-plastic ratios below the attack site density correlated with accumulation of those same compounds. This dissertation addresses gaps in the fundamental understanding of microbial consortia degradation of polyesters and the related role of heterogenous catalysis in enzymatic depolymerization.","abstract_has_math":false,"creators":["Foster, Marc J."],"institution":"Massachusetts Institute of Technology and Woods Hole Oceanographic Institution","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":["Plata, Desiree L."],"committee_chairs":[],"committee_members":[],"year":2026,"date_issued":"2026-05","date_published":"2026-05","updated_at":"2026-07-27T22:05:06Z","subjects":["Bacterial interactions","Enzyme kinetics","Polyesters"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier.doi","label":"DOI","values":["10.1575/1912/73005"],"render_values":[{"text":"10.1575/1912/73005","href":"https://doi.org/10.1575/1912/73005","code":true}]}]},"links":{"outbound_url":"https://hdl.handle.net/1912/73005","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Plata, Desiree L."]},{"key":"dc:creator","label":"Author","values":["Foster, Marc J."]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2026-05-29T20:05:12Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2026-05-29T20:05:12Z"]},{"key":"dc:date.issued","label":"Date","values":["2026-05"]},{"key":"dc:publisher","label":"Institution","values":["Massachusetts Institute of Technology and Woods Hole Oceanographic Institution"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Bacterial interactions","Enzyme kinetics","Polyesters"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.doi","label":"DOI","values":["10.1575/1912/73005"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://hdl.handle.net/1912/73005"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Environmental Chemistry at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution May 2026."]},{"key":"dc:description.abstract","label":"Abstract","values":["Plastic waste accumulation in the environment is a global concern. With production of these materials projected to increase, strategies to enhance polymer degradability in natural systems are necessary to reduce their environmental accumulation. In this dissertation, the environmental biodegradation of copolyesters was explored to understand the biological processes that control the removal of these materials in natural systems. First, the role of microbial consortia over single organisms in the degradation of poly(butylene sebacate coterephthalate) (PBSeT, a biodegradable alternative to commodity plastics) was investigated. Using enrichment cultures from the Mediterranean Sea, a set of bacteria were isolated and their individual contributions toward polymer degradation assessed via coculture respiration assays, monoculture growth measurements, DOC accumulation and removal tracking, and quantification of specific polymer degradation products. The results show depolymerization was controlled by a bacterium that metabolized only one monomer component of the polymer, while downstream consumers were required to remove the other moieties of the polymer. Second, the influence of growth rate and substrate preference on the success of degrader-consumer pairs was explored using two bacteria isolated from the previous PBSeT enrichment experiments. Monoculture Monod kinetics on the monomers of the polymer revealed each bacterium’s preference and competitiveness for PBSeT substrates. Subsequently, coculture incubations with the whole plastic revealed how these dynamics manifest in complex systems. Informed by measured kinetic parameters, modelling was then utilized to demonstrate the influence of changing consumer growth rates on the success of the pair. The results demonstrated that growth rate, and not just metabolic capability, dictated which part of the polymer was consumed and by which bacterium. Third, the effect of cutinase adsorption to plastic surfaces on the distribution of dissolved degradation products during enzymatic depolymerization was explored. Using a commercial cutinase from the organism Humicola insolens, conventional and inverse Michaelis-Menten kinetics were employed to extract catalytic turnover rates and attack-site densities. Additionally, specific oligomeric products were quantified and tracked over time. These results illustrated that when the enzyme-to-plastic ratio exceeded the attack site density, larger oligomers were broken down in the solution phase, whereas enzyme-to-plastic ratios below the attack site density correlated with accumulation of those same compounds. This dissertation addresses gaps in the fundamental understanding of microbial consortia degradation of polyesters and the related role of heterogenous catalysis in enzymatic depolymerization."]},{"key":"dc:title","label":"Title","values":["Bacterial interactions and enzyme kinetics in environmental polyester degradation"]}]}],"canonical_facts":{"dc:contributor.advisor":["Plata, Desiree L."],"dc:creator":["Foster, Marc J."],"dc:date.accessioned":["2026-05-29T20:05:12Z"],"dc:date.available":["2026-05-29T20:05:12Z"],"dc:date.issued":["2026-05"],"dc:description":["Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Environmental Chemistry at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution May 2026."],"dc:description.abstract":["Plastic waste accumulation in the environment is a global concern. With production of these materials projected to increase, strategies to enhance polymer degradability in natural systems are necessary to reduce their environmental accumulation. In this dissertation, the environmental biodegradation of copolyesters was explored to understand the biological processes that control the removal of these materials in natural systems. First, the role of microbial consortia over single organisms in the degradation of poly(butylene sebacate coterephthalate) (PBSeT, a biodegradable alternative to commodity plastics) was investigated. Using enrichment cultures from the Mediterranean Sea, a set of bacteria were isolated and their individual contributions toward polymer degradation assessed via coculture respiration assays, monoculture growth measurements, DOC accumulation and removal tracking, and quantification of specific polymer degradation products. The results show depolymerization was controlled by a bacterium that metabolized only one monomer component of the polymer, while downstream consumers were required to remove the other moieties of the polymer. Second, the influence of growth rate and substrate preference on the success of degrader-consumer pairs was explored using two bacteria isolated from the previous PBSeT enrichment experiments. Monoculture Monod kinetics on the monomers of the polymer revealed each bacterium’s preference and competitiveness for PBSeT substrates. Subsequently, coculture incubations with the whole plastic revealed how these dynamics manifest in complex systems. Informed by measured kinetic parameters, modelling was then utilized to demonstrate the influence of changing consumer growth rates on the success of the pair. The results demonstrated that growth rate, and not just metabolic capability, dictated which part of the polymer was consumed and by which bacterium. Third, the effect of cutinase adsorption to plastic surfaces on the distribution of dissolved degradation products during enzymatic depolymerization was explored. Using a commercial cutinase from the organism Humicola insolens, conventional and inverse Michaelis-Menten kinetics were employed to extract catalytic turnover rates and attack-site densities. Additionally, specific oligomeric products were quantified and tracked over time. These results illustrated that when the enzyme-to-plastic ratio exceeded the attack site density, larger oligomers were broken down in the solution phase, whereas enzyme-to-plastic ratios below the attack site density correlated with accumulation of those same compounds. This dissertation addresses gaps in the fundamental understanding of microbial consortia degradation of polyesters and the related role of heterogenous catalysis in enzymatic depolymerization."],"dc:identifier.doi":["10.1575/1912/73005"],"dc:identifier.uri":["https://hdl.handle.net/1912/73005"],"dc:publisher":["Massachusetts Institute of Technology and Woods Hole Oceanographic Institution"],"dc:subject":["Bacterial interactions","Enzyme kinetics","Polyesters"],"dc:title":["Bacterial interactions and enzyme kinetics in environmental polyester degradation"],"dc:type":["Thesis"]},"updated_at":"2026-07-27T22:05:06Z"}