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Interfacial and Biological Properties of Living Materials

Balmuri, Sricharani (2023) Interfacial and Biological Properties of Living Materials. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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Fluid interfaces are energy rich environments where a high degree of complex physical and chemical stresses exists. A typical bacterium of size comparable to a colloidal particle, adsorbed at the fluid interfaces experiences trapping energies so high that its adsorption is nearly irreversible. This poses survival threat to bacteria, to which they respond by initiating a dynamic process resulting in production of a polymer matrix, forming interfacial bacterial films with health, industrial, and environmental implications. This dissertation research is motivated by the need to enrich knowledge about specific metabolic and mechanical processes during bacterial colonization at fluid interfaces with applications in medicine and in bioremediation. Clinical isolates of Pseudomonas aeruginosa with distinct phenotypes isolated from cystic fibrosis patients were investigated for their ability to remodel interfacial environments. Specifically, our investigations shed light on “mucoid-switch” of P. aeruginosa and the underlying upregulated expression of extracellular polymeric substances –alginate, pel and psl– to survive interfacial stress. Additionally, the ability of mixed species biofilms to remodel the interfacial films was studied using mucoid and non-mucoid P. aeruginosa in the presence of Staphylococcus aureus. Further, the efficiency of N-acetyl cysteine and cysteamine in disrupting the interfacial biofilms was evaluated. On the other hand, the competency of beneficial bacteria such as Alcanivorax borkumensis to populate oil spill regions was investigated. A. borkumensis is a non-motile hydrocarbonoclastic bacteria that produces biosurfactant to emulsify the oil-water interfaces and alleviate interfacial stress. Eco-friendly wax products which can adsorb to fluid interfaces and reduce the interfacial tension were studied as a secondary oil-remediation technology. This led to the development of hollow wax microsorbents with an oil absorption capacity of 5 times the dry mass and with a potential to expediate the process of bioremediation. Overall, knowledge gained through this study will open avenues to develop new technologies to mimic and manipulate the bacteria at oil-water interfaces for applications in anti-fouling and bioremediation.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Balmuri, Sricharanisrb121@pitt.edusrb1210000-0001-8671-1986
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Thesis AdvisorNiepa, Tagbo H. R.tniepa@pitt.edutniepa
Committee MemberVelankar,
Committee MemberShoemaker,
Committee MemberRobertson,
Committee MemberStoodley,
Date: 19 January 2023
Date Type: Publication
Defense Date: 27 April 2022
Approval Date: 19 January 2023
Submission Date: 17 November 2022
Access Restriction: 2 year -- Restrict access to University of Pittsburgh for a period of 2 years.
Number of Pages: 201
Institution: University of Pittsburgh
Schools and Programs: Swanson School of Engineering > Chemical Engineering
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: Fluid interfaces, interfacial tension, bacterial films, Pseudomonas aeruginosa, Staphylococcus aureus, biofilm viscoelasticity, Cystic fibrosis, Alcanivorax borkumensis, Bioremediation
Date Deposited: 19 Jan 2023 19:27
Last Modified: 19 Jan 2023 19:27


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