Engineering Commons^™

Modeling The Production Of Microalgal Biomass In Large Water Resource Recovery Facilities And Its Processing Into Various Commodity Bioproducts, James Pierson, Gopi Raju Makkena, Sandeep Kumar, Vinod Kumar, Vivekanand Vivekanand, Hasan Husain, Muhammad Ayser, Venkatesh Balan

Civil & Environmental Engineering Faculty Publications

Algae are capable of sequestering nutrients such as nitrates and phosphates from wastewater in the presence of sunlight and carbon dioxide (CO₂) to build up their body mass and help combat climate change. In the current study, we carried out different case studies to estimate the volume of algal biomass that could be produced annually using the rotating algal biofilm (RAB) method in three large-scale water resource recovery facilities (WRRFs) in Texas: Fort Worth, Dallas, and Houston. We calculated the total amount of lipids, carbohydrates, and proteins that could be fractionated from the algal biomass while using the …

Impact Of Pipe Material On Microbial Communities In Biofilm Samples From Full-Scale Drinking Water Distribution Systems, San Marie Victoria Thomson

Master's Theses (2009 -)

The drinking water distribution system (DWDS) provides a habitat particularly supportive to biofilm-forming bacteria that can attach to pipe walls. These biofilms comprise the majority of bacteria in the DWDS, yet they have been understudied with respect to the pipe material on which they form. Biofilms can accelerate disinfectant decay, promote corrosion of pipes, and harbor opportunistic pathogens (OPs). The choice of pipe material could have a long-lasting effect on the characteristics of the biofilms formed in DWDSs. In this study, the impact of pipe material on biofilms residing in full-scale drinking water pipes was investigated by obtaining biofilm samples …

Biofilms: Formation, Research Models, Potential Targets, And Methods For Prevention And Treatment, Yajuan Su, Jaime T. Yrastorza, Mitchell Matis, Jenna Cusick, Siwei Zhao, Guangshun Wang, Jingwei Xie

Department of Mechanical and Materials Engineering: Faculty Publications

Due to the continuous rise in biofilm-related infections, biofilms seriously threaten human health. The formation of biofilms makes conventional antibiotics ineffective and dampens immune clearance. Therefore, it is important to understand the mechanisms of biofilm formation and develop novel strategies to treat biofilms more effectively. This review article begins with an introduction to biofilm formation in various clinical scenarios and their corresponding therapy. Established biofilm models used in research are then summarized. The potential targets which may assist in the development of new strategies for combating biofilms are further discussed. The novel technologies developed recently for the prevention and treatment …

The Role Of Extracellular Polymeric Substances In The Accumulation And Transport Of Polystyrene Nanoparticles In Biofilms, Joann Marie Rodríguez Suarez

Doctoral Dissertations

With the increasing number of nanotechnology applications, it is reasonable to expect nanoparticles to be ubiquitous in biofilms found in natural and engineered aquatic systems. We studied the impact of the degree of cross-linking on the deposition and diffusion of polystyrene nanoparticles (NPs) in alginate model biofilm matrices in the presence and absence of calcium cross-linkers using image correlation methods and single particle tracking. We found that cross-linking increases the viscoelasticity and hydration of the polymeric matrix and leads to structural changes that can restrict and alter the diffusive behavior of NPs, but the magnitude of the effects on diffusion …

A New Spatially-Resolved Method To Sample Biofilms From Drinking Water Fountains, Yi Liu

McKelvey School of Engineering Theses & Dissertations

A drinking fountain, also called a water fountain, is a facility designed to provide drinking water in public space. It consists of a basin and a spout. The users need to bend down to the stream to collect or drink water. The history of water fountains can be traced back to ancient Rome. Even before potable water was provided to individual homes, water for drinking was already made available to citizens through access to public fountains. Nowadays, drinking water fountains usually exist in public places, like schools, hospitals, and libraries. Many jurisdictions in the United States require drinking fountains to …

Metabolic Modeling Of Multispecies Microbial Biofilms, Poonam Phalak

Doctoral Dissertations

Biofilms are ubiquitous in medical, environmental, and engineered microbial systems. The majority of naturally occurring microbes grow as mixed species biofilms. These complicated biofilm consortia are comprised of many cell phenotypes with complex interactions and self-organized into three-dimensional structures. Approximately 2% of the US population suffers from non-healing chronic wounds infected by a combination of commensal and pathogenic bacteria whereas about 500,000 cases of Clostridium difficile infections (CDI) are reported annually. These polymicrobial infections are often resilient to antibiotic treatment due to the nutrient-rich environments and species interactions that promote community stability and robustness. This thesis focusses on developing metabolic …

Observations Of Shear Stress Effects On Staphylococcus Aureus Biofilm Formation, Erica Sherman, Kenneth W. Bayles, Derek Moormeir, Jennifer Endres, Timothy Wei

Department of Mechanical and Materials Engineering: Faculty Publications

Staphylococcus aureus bacteria form biofilms and distinctive microcolony or “tower” structures that facilitate their ability to tolerate antibiotic treatment and to spread within the human body. The formation of microcolonies, which break off, get carried downstream, and serve to initiate biofilms in other parts of the body, is of particular interest here. It is known that flow conditions play a role in the development, dispersion, and propagation of biofilms in general. The influence of flow on microcolony formation and, ultimately, what factors lead to microcolony development are, however, not well understood. The hypothesis being examined is that microcolony structures form …

The Success, Morphology, And Performance Of Oxygenic Photogranules Under Light-Induced Stress Conditions, Samuel Downes

Environmental & Water Resources Engineering Masters Projects

No abstract provided.

Rapid Sample Processing Of Foodborne Pathogens Using Cross-Flow Microfiltration, Casey Bomrad, Michael R. Ladisch, Linda Liu, Jessica Lynn Zuponcic, Eduardo Ximenes

The Summer Undergraduate Research Fellowship (SURF) Symposium

Foodborne illnesses are a prominent issue, causing 48 million illnesses annually. The Escherichia coli O157:H7 outbreak in romaine lettuce is a recent example. The source of the pathogen was contaminated irrigation water. The most common methods for detecting foodborne pathogens involve cultivation and enrichment of food samples. The enrichment steps are time-consuming, taking 24 to 72 hours to complete. Our study aims to accelerate irrigation water sample preparation for pathogenic microorganism fast detection through cross-flow microfiltration. This is accomplished by a device called a continuous cell concentration and recovery device (C3D). The C3D uses cross-flow microfiltration in a hollow fiber …

Moving Bed Biofilm Reactors: Evaluation Of Geometry, Attachment Surface Material And Biofilm Populations On The Uptake Of Ammonia And Synthetic Organic Contaminants In Wastewater., Patrick D. Mclee

Civil Engineering ETDs

Plastic biofilm carriers are used in biological wastewater treatment to encourage the attachment and retention of microorganisms that metabolize pollutants. The following research was conducted to better understand how different characteristics of the biofilm carrier affect the treatment performance of the attached biofilms in moving bed bioreactors. Lab scale reactors were used in this study to grow nitrifying biofilms in reactors with contrasting and controlled conditions. The effect of surface geometry on nitrification performance was evaluated by testing commercially available moving bed bioreactor media that contrast in physical design, and by varying operational parameters. Additionally, mature biofilm from a similar …

Novel Approaches To Mitigating Bacterial Biofilm Formation And Intercellular Communication, Stephen Kasper

Legacy Theses & Dissertations (2009 - 2024)

Long thought of as solitary single-cell organisms, it is now widely accepted that bacteria can act and cooperate as social organisms. Phenomena such as biofilm formation and quorum sensing (QS) are two intimately intertwined cooperative behaviors that significantly contribute to the pathogenesis of many bacteria. Biofilms are surface associated communities of bacteria encased in a secreted extracellular matrix, which provides several advantages over an individualized lifestyle, such as increased protection from antimicrobial agents as well as enhanced opportunity for the exchange of genetic material. Bacterial QS is a system of population-based communication through the production, sensing, and response to chemical …

Mechanism Of Interaction Of Peptide Modified Nanoparticles With Porphyromonas Gingivalis., Ankita Jain

Electronic Theses and Dissertations

Studies suggest that P. gingivalis functions as a keystone pathogen and interacts with primary colonizers in the supragingival biofilm such as S. gordonii. This interaction contributes to the initial colonization of the oral cavity by P. gingivalis and thus represents a potential target for therapeutic intervention. We have identified a peptide (BAR) derived from the streptococcal SspB protein that functions to inhibit P. gingivalis adherence to S. gordonii. In addition, we showed that nanoparticles (NPs) functionalized with BAR inhibit this interaction more potently than free soluble peptide, possibly by promoting interaction with P. gingivalis at higher valency than …

Metabolic Modeling Of A Chronic Wound Biofilm Consortium Predicts Spatial Partitioning Of Bacterial Species, Poonam Phalak, Jin Chen, Ross P. Carlson, Michael A. Henson

Chemical Engineering Faculty Publication Series

Background

Chronic wounds are often colonized by consortia comprised of different bacterial species growing as biofilms on a complex mixture of wound exudate. Bacteria growing in biofilms exhibit phenotypes distinct from planktonic growth, often rendering the application of antibacterial compounds ineffective. Computational modeling represents a complementary tool to experimentation for generating fundamental knowledge and developing more effective treatment strategies for chronic wound biofilm consortia.

Results

We developed spatiotemporal models to investigate the multispecies metabolism of a biofilm consortium comprised of two common chronic wound isolates: the aerobe Pseudomonas aeruginosa and the facultative anaerobe Staphylococcus aureus. By combining genome-scale metabolic …

Biofilm Growth Kinetics And Nutrient (N/P) Adsorption In An Urban Lake Using Reclaimed Water: A Quantitative Baseline For Ecological Health Assessment, Tianzhi Wang, Zhenci Wu, Yunkai Li, Mingchao Liang, Zhenhua Wang, Paul Hynds

Articles

Reclaimed wastewater reuse represents an effective method for partial resolution of increasing urban water shortages; however, reclaimed water may be characterized by significant contaminant loading, potentially affecting receiving ecosystem (and potentially human) health. The current study examined biofilm growth and nutrient adsorption in Olympic Lake (Beijing), the largest artificial urban lake in the world supplied exclusively by reclaimed wastewater. Findings indicate that solid particulate, extracellular polymeric substance (EPS) and metal oxide (Al, Fe, Mn) constituent masses adhere to a bacterial growth curve during biofilm formation and growth. Peak values were observed after ≈30 days, arrived at dynamic stability after ≈50days …

Electrochemical Control Of Bacterial Persister Cells, Tagbo Herman Roland Niepa

Dissertations - ALL

The emergence of antibiotic-resistant bacteria has presented an increasing challenge to infection control. Conventional methods of antibacterial treatment involving high dose of antibiotics or surgical intervention have proven insufficient for eradicating persistent infections, such as those associated with medical implants. It is well recognized that bacterial populations commonly contain a small percentage of phenotypic variants, known as persister cells, which are metabolically inactive and extremely tolerant to antibiotics. When the antibiotic treatment is stopped, surviving persister cells can regenerate the bacterial population with a similar percentage of persister cells. Thus, persistence presents a great challenge to curing chronic infections.

In …

Did Mineral Surface Chemistry And Toxicity Contribute To Evolution Of Microbial Extracellular Polymeric Substances?, Jie Xu, Jay M. Campbell, Nianli Zhang, William J. Hickey, Nita Sahai

Nita Sahai

Modern ecological niches are teeming with an astonishing diversity of microbial life in biofilms closely associated with mineral surfaces, which highlights the remarkable success of microorganisms in conquering the challenges and capitalizing on the benefits presented by the mineral-water interface. Biofilm formation capability likely evolved on early Earth because biofilms provide crucial cell survival functions. The potential toxicity of mineral surfaces toward cells and the complexities of the mineral-water-cell interface in determining the toxicity mechanisms, however, have not been fully appreciated. Here, we report a previously unrecognized role for extracellular polymeric substances (EPS), which form biofilms in shielding cells against …

Development Of A Moldable Composite Bone Graft Substitute Releasing Antibacterial And Osteogenic Drugs, Matthew E. Brown

Theses and Dissertations--Biomedical Engineering

Large infected bone defects (IBD) are very complicated to treat due to their high variability; they often require multiple procedures. Bone autografts are the gold standard for treatment but have several drawbacks, such as a need for a second surgery site, limited grafting material, and donor site morbidity. The objective of this research was to develop a moldable synthetic bone grafting material capable of releasing both antimicrobial and osteogenic drugs over a clinically relevant time course for the treatment of IBDs. Current treatment methods for large IBDs require two separate procedures to treat the bone defect and the infection.

This …

Method For Synchrotron X-Ray Computed Tomographic Imaging Of Biofilms In Porous Media, Corey Matthew Klibert

LSU Master's Theses

Modeling of biofilms in porous media at pore scale resolution has been hindered by the lack of available experimental techniques to non-destructively image biofilm structure at these resolutions. Researchers have relied upon simulation rather than experimentation to produce pore-scale biofilm models, using simplifying assumptions governing microbial growth such as Monod kinetics and random biofilm seeding locations to generate biofilms in simulated environments. This study investigated the use of absorption-edge synchrotron X-ray computed microtomography (SXCMT) in combination with a contrast agent, Lugol’s iodine solution (10% KI/5% I2), to nondestructively obtain three-dimensional images of biofilms at pore-scale resolution. The study examined and …

Bacterial Growth On Metal And Non-Metal Surfaces In A Static Bioreactor, Rolan Yuk Loong Liong

Master's Theses

Research was conducted to observe bacterial growth on the surface of metals in a static bioreactor. Metal and non-metal samples were subjected to bacterial exposure (1 day and 9 days). The metal samples were surface treated prior to bacterial exposure. The microstructures of the surface treated samples were analyzed by optical microscopy. After exposure, the microstructures of the samples were analyzed by scanning electron microscopy (SEM). The analysis suggested that microbial attachment on the surface was related to the underlying microstructure of steel. The preferential attachment of microbes could potentially be influenced by cathodic and anodic regions created by the …

Microfluidic-Assisted Atomic Force Microscopy For The Mechanical Characterization Of Soft Biological Materials, Aaron Peter Mosier

Legacy Theses & Dissertations (2009 - 2024)

Viable methods for bacterial biofilm remediation require a fundamental understanding of biofilm mechanical properties and their dependence on dynamic environmental conditions. Mechanical test data, quantifying elasticity or adhesion, may be used to perform physical modeling of biofilm behavior, thus enabling the development of novel remediation strategies. To achieve real-time, dynamic measurements of these properties, a novel analysis platform consisting of a microfluidic flowcell device has been designed and fabricated for in situ analysis using atomic force microscopy (AFM) and confocal laser scanning microscopy (CLSM). The flowcell consists of microfluidic channels for biofilm establishment that are then converted into an open …

Investigation Of Best Practices For Maintenance Of Concrete Bridge Railings, Angel Luis Lence

LSU Master's Theses

Biodeterioration on concrete surfaces of vertical elements of bridges represents a serious challenge to the highway infrastructure in Louisiana. This investigation aims to document the causes of biodeterioration of concrete surfaces and to document current conventional and state-of-the-art practices implemented to prevent and clean biofilm. A comprehensive literature review of previous research has been carried out in order to determine the cause and mechanisms of the biodeterioration as well as to identify current methods that state DOTs have implemented in order to maintain their bridges and allow them to function in optimal structural and performance conditions. A survey was developed …

Did Mineral Surface Chemistry And Toxicity Contribute To Evolution Of Microbial Extracellular Polymeric Substances?, Jie Xu, Jay M. Campbell, Nianli Zhang, William J. Hickey, Nita Sahai

College of Polymer Science and Polymer Engineering

Modern ecological niches are teeming with an astonishing diversity of microbial life in biofilms closely associated with mineral surfaces, which highlights the remarkable success of microorganisms in conquering the challenges and capitalizing on the benefits presented by the mineral-water interface. Biofilm formation capability likely evolved on early Earth because biofilms provide crucial cell survival functions. The potential toxicity of mineral surfaces toward cells and the complexities of the mineral-water-cell interface in determining the toxicity mechanisms, however, have not been fully appreciated. Here, we report a previously unrecognized role for extracellular polymeric substances (EPS), which form biofilms in shielding cells against …

Combating Antibiotic Resistance Through Development Of A Novel Antimicrobial Delivery Vehicle, Alex Hatch

Undergraduate Honors Capstone Projects

A thermoreversible gel for antimicrobial agent delivery would provide a novel platform suitable for medical applications from persistent infections arising from localized biofilms. Thermoreversible gels could be used to coat medical implants, to inject for subdermal treatments, or to implement in topical applications. FDA approved Pluronics® form thermoreversible gels and certain Pluronics® display inherent varying degrees of antimicrobial activity. Pluronics® have been shown to affect efflux pumps, and reduce ATP levels within the bacterial cell. In combination with antibiotics and other pharmaceuticals, Pluronics® have been used to sequester drugs and act as a delivery vehicle. With advances in nanomedicine, nanoparticles …

Effects Of Srb Biofilm And Corrosion Product Films On Corrosion Behavior Of Carbon Steel, Jing Lin

Journal of Electrochemistry

Electrochemical techniques and surface analysis techniques were applied to study corrosion characteristic of A3 steel.The effects on corrosion behavior of A3 steel by sulfate-reducing bacteria(SRB)(biotic media)and corrosion product(abiotic media)were studied.The results showed that biofilms and corrosion product films play different role during different stages.Biofilms were easier flaky with increasing of its thickness.Non-uniform biofilms reduced pitting corrosion of the specimens.The corrosion product films formed under abiotic conditions were more adherently to the surface of the metal than those formed in biogenic media.

Heterogeneity Of Natural Biofilm Communities, J. R. Lawrence, D. R. Korber, G. M. Wolfaardt

Cells and Materials

Scanning confocal laser microscopy (SCLM) studies have shown that microbial biofilms consist of a spatially heterogeneous arrangement of bacterial cells, biogenic extracellular material, and void space. Biofilm architecture is dominated by the presence of cell aggregates interspersed by channels, the arrangement of which varies for different hydrodynamic regimes, ages, species composition, or nutrient status. This organization may regulate the flux of nutrients and oxygen, creating chemical microenvironments (Eh, pH) facilitating the growth of aerobic heterotrophs and anaerobes. The presence of microenvironments has been confirmed using laser microscopy and environmentally sensitive fluorescent probes. In addition, changes in cell number and growth …

Lead Distribution In A Simulated Aquatic Environment: Effects Of Bacterial Biofilms And Iron Oxide, Yarrow M. Nelson, Waihung Lo, Leonard W. Lion, Michael L. Shuler, William C. Ghiorse

Civil and Environmental Engineering

Biofilms influence the transport and fate of heavy metals in aquatic environments both directly by adsorption and complexation reactions and indirectly via interactions with oxides of iron and manganese. These reactions were investigated by introducing lead into a continuous-flow biofilm reactor that was designed to simulate conditions in a flowing freshwater aquatic environment. The reactor provided controlled conditions, and use of a chemically-defined growth medium allowed calculation of lead speciation with a chemical equilibrium program (MINEQL). Pseudomonas cepacia was employed as a test cell strain because of its ability to grow and form biofilms in the defined medium. This bacterium …

Some Observations On The Structure Of Encrusting Biofilms Of Proteus Mirabilis On Urethral Catheters, C. Winters, D. J. Stickler, N. S. Howe, T. J. Williams, N. Wilkinson, C. J. Buckley

Cells and Materials

A physical model of the bladder has been used to study the process of urinary catheter encrustation. Techniques have been devised for the preparation of sections through these encrustations in situ on the luminal surfaces of catheters and for mapping the distribution of calcium and magnesium in the biofilms. Transmission electron microscopy on these sections showed struvite-like crystals lying in the matrix and in direct contact with the catheter surface. Calcium phosphate ("bioapatite") was distributed throughout the film and many of these amorphous particles appear to have cells at their cores. Freeze-substituted sections of biofilms also showed electron dense materials …

Scanning Electron Microscopy Study Of Biofilms On Silicone Voice Prosthesis, T. R. Neu, F. Dijk, G. J. Verkerke, H. C. Van Der Mei, H. J. Busscher

Cells and Materials

Patients after laryngectomy often receive silicone made voice prostheses fot speech rehabilitation. The prosthesis is inserted in a shunt between the trachea and the digestive tract. As the prosthesis is placed in a nonsterile environment it becomes rapidly colonized by microorganisms eventually leading to failure and frequent exchange of the implant. In this study, explanted "Groningen Button" silicone voice prostheses were used to investigate by scanning electron microscopy the biofilm developing on the implant. Two main types of microbial colonization forms could be distinguished. Firstly, macroscopically visible, single colonies dominating on the esophagus side of the prosthesis were found, which …