Inactivation of pathogens on food and contact surfaces using ozone as a biocidal agent

This study focuses on the inactivation of a range of food borne pathogens using ozone as a biocidal agent. Experiments were carried out using Campylobacter jejuni, E. coli and Salmonella enteritidis in which population size effects and different treatment temperatures were investigate

PROGRAM, THE NEBRASKA ACADEMY OF SCIENCES: One Hundred-Thirty-First Annual Meeting, APRIL 23-24, 2021. ONLINE

AFFILIATED SOCIETIES OF THE NEBRASKA ACADEMY OF SCIENCES, INC. 1.American Association of Physics Teachers, Nebraska Section: Web site: http://www.aapt.org/sections/officers.cfm?section=Nebraska 2.Friends of Loren Eiseley: Web site: http://www.eiseley.org/ 3.Lincoln Gem & Mineral Club: Web site: http://www.lincolngemmineralclub.org/ 4.Nebraska Chapter, National Council for Geographic Education 5.Nebraska Geological Society: Web site: http://www.nebraskageologicalsociety.org Sponsors of a $50 award to the outstanding student paper presented at the Nebraska Academy of SciencesAnnual Meeting, Earth Science /Nebraska Chapter, National Council Sections 6.Nebraska Graduate Women in Science 7.Nebraska Junior Academy of Sciences: Web site: http://www.nebraskajunioracademyofsciences.org/ 8.Nebraska Ornithologists’ Union: Web site: http://www.noubirds.org/ 9.Nebraska Psychological Association: http://www.nebpsych.org/ 10.Nebraska-Southeast South Dakota Section Mathematical Association of America: Web site: http://sections.maa.org/nesesd/ 11.Nebraska Space Grant Consortium: Web site: http://www.ne.spacegrant.org/ CONTENTS AERONAUTICS & SPACE SCIENCE ANTHROPOLOGY APPLIED SCIENCE & TECHNOLOGY BIOLOGICAL & MEDICAL SCIENCES COLLEGIATE ACADEMY: BIOLOGY COLLEGIATE ACADEMY: CHEMISTRY & PHYSICS EARTH SCIENCES ENVIRONMENTAL SCIENCES GENERAL CHEMISTRY GENERAL PHYSICS TEACHING OF SCIENCE & MATHEMATICS 2020-2021 PROGRAM COMMITTEE 2020-2021 EXECUTIVE COMMITTEE FRIENDS OF THE ACADEMY NEBRASKA ACADEMY OF SCIENCS FRIEND OF SCIENCE AWARD WINNERS FRIEND OF SCIENCE AWARD TO DR PAUL KAR

An integrative modelling framework for multicellular systems

Ph. D. Thesis.Multicellular systems exhibit complex population scale behaviour that emerge from the interactions between constituent cells. Integrative modelling (IM) techniques are a valuable tool for studying these systems capturing processes that occur at many temporal and spatial scales. The application of IM to multicellular systems is challenging as it is knowledge and resource intensive, additionally there do not exist effective frameworks or tools, inhibiting its wider application in Systems and Synthetic biology. This thesis presents Simbiotics, a novel IM framework for the modelling of mixed species bacterial consortia. Simbiotics is a spatially explicit multi-scale modelling platform for the design, simulation and analysis of bacterial populations. A library of modules simulating features such as cell geometries, physical force dynamics, genetic circuits, metabolic pathways, chemical diffusion and cell interactions is implemented, that the modeller may compose into their own custom models. Common modelling methods such as Boolean networks, differential equations, Gillespie models and SBML are implemented. With the platform in-silico experiments can be conducted with programmed experiment interactions, data collection and analysis. The framework is extendable and modular, allowing for the library to be updated as knowledge progresses. A novel file format for the reuse and communication of multicellular models and simulation methods is also implemented. Additionally an intuitive graphical user interface, Easybiotics, has been developed allowing for multicellular modelling with minimal programming experience. Four novel case studies are pursued with Simbiotics studying the emergent behaviours of multicellular systems. The effect of physical cell interactions are characterised in the first two studies. Investigation into how chemical signalling and intracellular dynamics influence population dynamics and patterns are studied in the final two case studies. These studies demonstrate how Simbotics can be integrated into a Systems/ Synthetic biology workflow, facilitating the studying of natural systems and as a CAD tool for developing novel synthetic systems.EPSR

The emergence of biofilms:Computational and experimental studies

The response of biofilms to any external stimuli is a cumulative response aggregated from individual bacteria residing within the biofilm. The organizational complexity of biofilm can be studied effectively by understanding bacterial interactions at cell level. The overall aim of the thesis is to explore the complex evolutionary behaviour of bacterial biofilms. This thesis is divided into three major studies based on the type of perturbation analysed in the study. The first study analyses the physics behind the development of mushroom-shaped structures from the influence of nutrient cues in biofilms. Glazier-Graner-Hogeweg model is used to simulate the cell characteristics. From the study, it is observed that chemotaxis of bacterial cells towards nutrient source is one of the major precursors for formation of mushroom-shaped structures. The objective of the second study is to analyse the impact of environmental conditions on the inter-biofilm quorum sensing (QS) signalling. Using a hybrid convection-diffusion-reaction model, the simulations predict the diffusivity of QS molecules, the spatiotemporal variations of QS signal concentrations and the competition outcome between QS and quorum quenching mutant bacterial communities. The mechanical effects associated with the fluid-biofilm interaction is addressed in the third study. A novel fluid-structure interaction model based on fluid dynamics and structural energy minimization is developed in the study. Model simulations are used to analyse the detachment and surface effects of the fluid stresses on the biofilm. In addition to the mechanistic models described, a separate study is carried out to estimate the computational efficiency of the biofilm simulation models

Cancer drugs as drivers of antibiotic resistance

Antibiotics are the cornerstone for modern medicine, and their introduction into clinical use has made common medical procedures such as surgeries and cancer chemotherapy possible. The consequences of antimicrobial resistance (AMR), if it continues to rise on a global scale at its current speed, are expected to be staggering. It is well-known that antibiotics drive the evolution and spread of AMR, but the extent to which non-antibiotic drugs can do the same remains largely unknown. In this thesis, I have investigated whether drugs used in cancer therapy may drive AMR evolution in the common gut bacteria Escherichia coli. I screened a panel of 73 oncology compounds against 11 common AMR mechanisms, looking for combinations where expressing AMR gives bacteria fitness advantages in the presence of antineoplastic agents. Of the 23 strongest combinations identified in the screen, an in-depth study looking into the effects on bacterial evolution and the underlying molecular mechanisms has been conducted for one agent. I show that the widely used cytotoxic drug methotrexate (MTX), used both in the treatment of cancer as well as for many autoimmune diseases, can not only cause high-level trimethoprim (TMP) resistance at a wide range of concentrations. Furthermore, I have demonstrated that selection for TMP resistance takes place at MTX concentrations well below the concentrations known to inhibit growth. This is especially problematic when TMP resistance is plasmid-mediated, as MTX exposure will then select for practically any AMR determinant co-expressed on the same plasmid. With this work, we provide valuable insights into the effects that drugs used in cancer chemotherapy have on AMR evolution. A better understanding of the drivers of resistance, especially those directly affecting vulnerable patient groups, is essential if we hope to curb the spread and evolution of AMR

Molecular and ecological characterisation of Escherichia coli from plants

Abstract Escherichia coli is routinely isolated from vegetables and there is increasing evidence that plants are a secondary reservoir for commensal and pathogenic strains, but the ecological factors involved in the persistence of E. coli on plants are not clear. In this thesis, a comparative study was undertaken combining phenotypic and phylogenetic analyses of E. coli isolates from salads grown in the UK and the faeces of mammalian hosts. In vitro phenotypic profiling revealed significant differences according to the source of isolation: strains from plants were in the majority from phylogroup B1, displayed lower siderophore production, greater motility, higher biofilm production, and better growth on the aromatic compounds and sucrose. However, plant-associated isolates reached lower growth yields on many carbon sources, including several amino acids and common carbohydrates such as glucose and mannitol. The data obtained indicate that in addition to lateral gene transfer, variation (regulation or uptake) in core metabolic functions plays an important role in E. coli ecological adaptation. When the discriminating phenotypes were combined to generate a plant association index (PAi) to rank strains according to their potential to persist on plants, a strong association between PAi and phylogeny was found, notably high levels in phylogroup B1 and low levels in phylogroup B2 which could potentially constitute a good predictor for host specialisation and generalisation in E. coli. As a more applied and preliminary investigation, the question of how a strain with a medium level of PAi (GMB30) can influence the resident microflora of field- and laboratory-grown spinach was also addressed. Overall, this study shows that despite frequent acquisition and loss of traits associated with nonhost environments, the E. coli phylogroups differ substantially in their transmission ecology, and in the adaptation levels to their host

PROGRAM and PROCEEDINGS THE NEBRASKA ACADEMY OF SCIENCES -- April 22, 2022

Aeronautics & Space Science -- Chairperson(s): Dr. Scott Tarry & Michaela Lucas ANTHROPOLOGY SECTION Chairperson: Dr. Taylor Livingston APPLIED SCIENCE & TECHNOLOGY SECTION Chairperson: Mary Ettel BIOLOGICAL SCIENCES SECTION Chairperson: Therese McGinn BIOMEDICAL SCIENCES SECTION Chairperson: Annemarie Shibata CHEMISTRY SECTION Chairperson: Nathanael Fackler EARTH SCIENCES SECTION Chairperson: Irina Filina ENVIRONMENTAL SCIENCES SECTION Chairperson: Mark Hammer PHYSICS SECTION Chairperson: Adam Davis FRIENDS OF THE ACADEMY 2022 Maiben Lecturer: Dan Sitzman 2022 FRIEND OF SCIENCE AWARD TO: Julie Sigmon and Chris Schabe