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Understanding Natural Plastic Biodegradation: Case Study of Tenebrio Molitor.

紀錄類型:	書目-電子資源 : Monograph/item
Title/Author:	Understanding Natural Plastic Biodegradation: Case Study of Tenebrio Molitor./
Author:	Brandon, Anja Malawi.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 2020,
Description:	182 p.
Notes:	Source: Dissertations Abstracts International, Volume: 82-10, Section: B.
Contained By:	Dissertations Abstracts International82-10B.
Subject:	Microbiology. -
Online resource:	https://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=28403855
ISBN:	9798728203728

Understanding Natural Plastic Biodegradation: Case Study of Tenebrio Molitor.
Brandon, Anja Malawi.

Understanding Natural Plastic Biodegradation: Case Study of Tenebrio Molitor. - Ann Arbor : ProQuest Dissertations & Theses, 2020 - 182 p.

Source: Dissertations Abstracts International, Volume: 82-10, Section: B.

Thesis (Ph.D.)--Stanford University, 2020.

This item must not be sold to any third party vendors.

We live in the "Age of Plastics," an era in which plastic's versatility, strength, and low production costs have led to its ubiquity. Plastics are often designed for single use, leading to the rapid accumulation of plastic waste. Much of this waste escapes formal collection and accumulates in natural environments, especially the ocean. Increasing restrictions on recycling and landfill space are rendering current waste management systems unable to address current and future plastic waste. Finding a way to degrade plastic waste into valuable, sustainable resources and permanently eliminate it from the pollution cycle is critical for the effective remediation of the natural environment and development of a sustainable future.A promising solution to achieve this goal is microbial biodegradation of plastics. However, the rate of plastic degradation by most mixed microbial cultures and isolated microorganisms is low. Efforts to improve plastic biodegradation have identified an environment in which a number of plastics can degrade at relatively rapid rates: the gut of mealworms (the larvae of Tenebrio molitorLinnaeus). Understanding the mechanisms and conditions required for degradation within the mealworm could enable the scaling-up of this process as a sustainable waste management strategy. The research described in this dissertation expands our understanding of naturally occurring plastic biodegradation mechanisms, drawing on insights from the study of the mealworm and its gut microorganisms to identify strategies whereby that understanding can be harnessed in engineered systems. These contributions advance the field of plastic biodegradation beyond a focus on isolated pure cultures to a deeper understanding about environments and necessary conditions for plastic degradation. With this more holistic approach, it is possible to move past the existing paradigm of single-use plastics to a future of sustainable, environmentally benign materials.Chapter 2 examines the ability of mealworms to degrade multiple types of plastics, specifically polyethylene (PE) and a mixture of two of the most common plastic wastes (PE and PS). This study found that polyethylene, polystyrene, and mixtures of the plastics degraded at comparable rates. Microbial analysis of the mealworm gut found several microorganisms strongly associated with the plastic-fed diets. These results provide the first evidence of a non-specific degradation mechanism within the mealworm gut and highlight the need for additional research to elucidate this mechanism.Chapter 3 investigates the ex situ polystyrene degradation achieved by the gut microbiome of plastic-degrading mealworms. The gut microbiome was cultured with PS as the only carbon source to enrich for ecient plastic-degradation and to enable the isolation of the bacteria involved. The mealworm gut environment was studied with and without the gut microbiome to explore the role the insect host during plastic degradation. This research revealed the important role of the mealworm host in secreting emulsifying factors that mediate plastic bioavailability. In addition, plastic-degrading microorganisms were identified as well as microbial secreted factors that enhance degradation. Chapter 3 demonstrated the ability to culture plastic-degrading bacteria, which may enable future investigations and bioaugmentation for enhanced plastic degradation.Chapter 4 explores the fate of chemical additives in plastics during degradation by mealworms to assess whether there is evidence of bioaccumulation. Specifically, this study examines the fate of hexabromocyclododecane (HBCD), a common flame retardant in PS products. The results reveal that HBCD is rapidly excreted and does not bioaccumulate within the mealworm biomass. PS-fed mealworm biomass was also used as a feed supplement for shrimp without evidence of HBCD bioaccumulation. Chapter 4 presents the first investigation into the fate of chemical additives during plastic degradation. This work demonstrates the need for further investigations into the environmental impact of secreted micro- and nano-plastic particles after plastic degradation and the continued need for green chemistry in designing additives.Chapter 5 presents a critical review on the state of plastic pollution and remediation strategies that contextualizes the research conducted in this thesis. The review analyzes the state of plastic pollution, bioplastic materials, and plastic biodegradation and presents a framework for transitioning from recalcitrant plastics to biodegradable and non-toxic replacement materials. This review provides a summary of the state of a rapidly expanding field and proposes directions for future research to achieve a sustainable future.The research summarized in this dissertation provides a comprehensive understanding the rapid biodegradation of plastics in an unexpected natural system: the gut of mealworms. Results from these studies contribute to the growing field of plastic degradation by illustrating how plastics are rapidly biodegraded within the mealworm gut and provides guidance on how this process might be replicated and scaled-up to enable a viable, sustainable alternative for plastic waste.

ISBN: 9798728203728Subjects--Topical Terms:

536250
Microbiology.
Subjects--Index Terms:

Plastic waste

Understanding Natural Plastic Biodegradation: Case Study of Tenebrio Molitor.
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520 $a We live in the "Age of Plastics," an era in which plastic's versatility, strength, and low production costs have led to its ubiquity. Plastics are often designed for single use, leading to the rapid accumulation of plastic waste. Much of this waste escapes formal collection and accumulates in natural environments, especially the ocean. Increasing restrictions on recycling and landfill space are rendering current waste management systems unable to address current and future plastic waste. Finding a way to degrade plastic waste into valuable, sustainable resources and permanently eliminate it from the pollution cycle is critical for the effective remediation of the natural environment and development of a sustainable future.A promising solution to achieve this goal is microbial biodegradation of plastics. However, the rate of plastic degradation by most mixed microbial cultures and isolated microorganisms is low. Efforts to improve plastic biodegradation have identified an environment in which a number of plastics can degrade at relatively rapid rates: the gut of mealworms (the larvae of Tenebrio molitorLinnaeus). Understanding the mechanisms and conditions required for degradation within the mealworm could enable the scaling-up of this process as a sustainable waste management strategy. The research described in this dissertation expands our understanding of naturally occurring plastic biodegradation mechanisms, drawing on insights from the study of the mealworm and its gut microorganisms to identify strategies whereby that understanding can be harnessed in engineered systems. These contributions advance the field of plastic biodegradation beyond a focus on isolated pure cultures to a deeper understanding about environments and necessary conditions for plastic degradation. With this more holistic approach, it is possible to move past the existing paradigm of single-use plastics to a future of sustainable, environmentally benign materials.Chapter 2 examines the ability of mealworms to degrade multiple types of plastics, specifically polyethylene (PE) and a mixture of two of the most common plastic wastes (PE and PS). This study found that polyethylene, polystyrene, and mixtures of the plastics degraded at comparable rates. Microbial analysis of the mealworm gut found several microorganisms strongly associated with the plastic-fed diets. These results provide the first evidence of a non-specific degradation mechanism within the mealworm gut and highlight the need for additional research to elucidate this mechanism.Chapter 3 investigates the ex situ polystyrene degradation achieved by the gut microbiome of plastic-degrading mealworms. The gut microbiome was cultured with PS as the only carbon source to enrich for ecient plastic-degradation and to enable the isolation of the bacteria involved. The mealworm gut environment was studied with and without the gut microbiome to explore the role the insect host during plastic degradation. This research revealed the important role of the mealworm host in secreting emulsifying factors that mediate plastic bioavailability. In addition, plastic-degrading microorganisms were identified as well as microbial secreted factors that enhance degradation. Chapter 3 demonstrated the ability to culture plastic-degrading bacteria, which may enable future investigations and bioaugmentation for enhanced plastic degradation.Chapter 4 explores the fate of chemical additives in plastics during degradation by mealworms to assess whether there is evidence of bioaccumulation. Specifically, this study examines the fate of hexabromocyclododecane (HBCD), a common flame retardant in PS products. The results reveal that HBCD is rapidly excreted and does not bioaccumulate within the mealworm biomass. PS-fed mealworm biomass was also used as a feed supplement for shrimp without evidence of HBCD bioaccumulation. Chapter 4 presents the first investigation into the fate of chemical additives during plastic degradation. This work demonstrates the need for further investigations into the environmental impact of secreted micro- and nano-plastic particles after plastic degradation and the continued need for green chemistry in designing additives.Chapter 5 presents a critical review on the state of plastic pollution and remediation strategies that contextualizes the research conducted in this thesis. The review analyzes the state of plastic pollution, bioplastic materials, and plastic biodegradation and presents a framework for transitioning from recalcitrant plastics to biodegradable and non-toxic replacement materials. This review provides a summary of the state of a rapidly expanding field and proposes directions for future research to achieve a sustainable future.The research summarized in this dissertation provides a comprehensive understanding the rapid biodegradation of plastics in an unexpected natural system: the gut of mealworms. Results from these studies contribute to the growing field of plastic degradation by illustrating how plastics are rapidly biodegraded within the mealworm gut and provides guidance on how this process might be replicated and scaled-up to enable a viable, sustainable alternative for plastic waste.
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