Microbial Physiology Commons^™

Exploring The Role Of Faecalibacterium Prausnitzii Metabolites In Modulating Fatty Acid Metabolism And Protecting Hepg2 Cells During Induced Steatosis, Morgan Martin, Emerald Cole

Student Scholar Symposium

The obesity epidemic has risen to astronomical numbers with over 650 million adults being classified as obese (BMI≥30). Obesity is of critical concern as excess body fat storage is a comorbidity to various diseases including type-2 diabetes, cardiovascular disease, and cancer. Although obesity has classically been attributed to genetics and unhealthy lifestyle choices, there is a growing interest in other factors affecting obesity, including the gut microbiome. For example, mice lacking a microbiome are resistant to weight gain even when placed on a high-calorie diet. It can then be concluded that bacteria and the metabolites they produce can dramatically affect …

Requirement Of Prepiilin Peptidase Activity For Variovorax Paradoxus Eps Flp/Fap Pilus Assembly, Jenny L. Lanthripp

Electronic Theses, Projects, and Dissertations

Variovorax paradoxus is a Gram-negative aerobic bacterium present in both soil and the human oral microbiome. This species contributes to biotransformation of xenobiotics and promotes plant growth. Interestingly, although the genome of strain EPS lacks the flagellum operon annotated in strain S110, the microbe remains motile, and flagella can be observed microscopically. To investigate this unexpected phenotype, motility mutants were enriched from a Tn5 mutant library using a liquid culture settling strategy. A total of 122 isolates were screened for motility defects, and 57 exhibited significantly reduced motility compared to the wild type. Rescue cloning revealed that over 60% of …

Investigating The Mechanisms Of Microbial Interactions Using A Model Cystic Fibrosis Polymicrobial Community, Bassam El Hafi

Dartmouth College Ph.D Dissertations

Cystic fibrosis (CF) airway microbial communities are complex ecosystems where interspecies interactions influence pathogen survival and disease progression. We leverage a CF-relevant in vitro four-species model composed of Pseudomonas aeruginosa, Staphylococcus aureus, Streptococcus sanguinis, and Prevotella melaninogenica, alongside a microbiome dataset with over 4,000 respiratory samples from publicly available sequencing data of CF patient samples, to explore the dynamics of microbial interactions in CF. On a broader scale, we performed microbial network analysis to examine how the latest modulator therapy, elexacaftor/tezacaftor/ivacaftor (ETI), might influence CF microbial communities. Our analysis revealed a reduction in node connections and …

Effect Of Red And Blue Light On Lipid, Protein, Carbohydrate, And Pigment Contents Of Navicula Sp., Sofyan Maulana, Aulia Setyo Nurul Hida, Ismia Wulandari, Siti Mudrikah, Dedy Kurnianto, Khusnul Qonita Maghfiroh, Ria Amelia, Tia Erfianti, Renata Adaranyssa Egistha Putri, Irika Devi Anggraini, Septhian Marno, Eko Agus Agus Suyono

Makara Journal of Science

Light quality critically modulates the physiology of diatoms, influencing photosynthetic efficiency and metabolite synthesis. This study examines how monochromatic red (620–750 nm) or blue (450–495 nm) light affects the biochemical profiles and pigment production in Navicula sp. versus white light (control). Cultures were grown in sterile f/2 medium, and biomass was tracked via OD₆₈₀. Biochemical analyses included lipids (Bligh and Dyer method), carbohydrates (phenol-sulfuric acid assay), proteins (Bradford assay), and pigments (spectrophotometric quantification). The growth dynamics were modeled using logistic and Gompertz equations. No significant differences in OD-based growth rates, carbohydrates, proteins, or lipids content were observed with …

Host, Microbiome, And Parasite: How Apicomplexan Microorganisms Interact With Gut Microbiota, Senia Bu, Andrew T. Ozga

Mako: NSU Undergraduate Student Journal

The gut microbiome, a complex ecosystem of microorganisms residing in the human gastrointestinal tract, plays a crucial role in maintaining overall health. It functions in immune system regulation, digestion, and protection against pathogens. Apicomplexan parasites, such as Toxoplasma gondii, Plasmodium spp., and Cryptosporidium spp., are major pathogens that can significantly disrupt the gut microbiota, leading to alterations in microbial composition and function. This review explores the bidirectional interactions between Apicomplexan parasites and the gut microbiome, focusing on how these parasites influence microbial diversity, immune responses, and host metabolism. It examines the mechanisms by which infection-induced inflammation, altered …

Long-Chain Fatty Acids Promote Candida Albicans Gut Colonization By Restructuring The Fungal Cell Surface, Musfirat Shubaita

Dissertations and Theses (Open Access)

Long-chain fatty acids promote Candida albicans gut colonization by restructuring the fungal cell surface

Musfirat Shubaita, BS

Advisory Professor: J. Christian Perez, Ph.D.

The yeast Candida albicans is a facultative anaerobe residing in the human digestive tract. Although fungal genetic determinants of mammalian host colonization have been identified, little is known about signals and molecules in the intestinal environment that influence C. albicans proliferation. Previously unpublished data from the Perez lab showed that oleic acid, one of the most abundant long-chain fatty acids in nature, promotes C. albicans colonization of the murine intestine. The goal of this research is to …

Impact Of Shear Flow On Marine Biofilms Using Hyperspectral Imaging, Shantanu Mahesh Kore

All Theses

Various microbial communities in marine biofilms cause biofouling on submerged surfaces, posing challenges to marine industries. Despite their ecological and economic importance, biofilms' biomechanical and biochemical responses to hydrodynamic shear stress are insufficiently understood, particularly in dynamic flow conditions. To fill this gap, our study uses an innovative fiber-optic hyperspectral imaging (HSI) system and a supercontinuum laser source to examine marine biofilms' structure, composition, and detachment behavior at different shear stress levels.

To detect spectral and spatial heterogeneity in live biofilms without labeling, we created a custom imaging pipeline that captures reflectance spectra in the 600-850 nm range, targeting microbial …

Metabolite Analysis To Understand Factors Limiting Microbial Fermentation At High Substrate Concentrations, Bishal D. Sharma

Dartmouth College Ph.D Dissertations

Clostridium thermocellum, a thermophilic anaerobic bacterium, holds promise as a biocatalyst for conversion of lignocellulosic biomass into biofuels. This microbe has been subjected to various metabolic engineering strategies, including the deletion of genes encoding secondary fermentation products such as H₂, formate, acetate, and lactate, as well as the expression of heterologous genes to redirect carbon flux toward ethanol production. Despite these efforts, achieving economically viable ethanol titers remains a challenge. We hypothesized that studying how intracellular metabolite concentrations change as fermentation stops could reveal metabolic bottlenecks or regulatory mechanisms limiting ethanol production at high titers. However, metabolomics studies at …

Improved Protein Splicing Through Viral Passaging, John Smetana

Scholars Week

Intervening proteins (inteins) are translated as subdomains within host proteins and removed through an intein-driven splicing reaction where the flanking sequences (exteins) are joined with a peptide bond. Previously, we developed a self-removing translation reporter for labeling Ebola virus (EBOV). In this reporter, an intein (RadA) containing the fluorescent protein ZsGreen (ZsG) is inserted within the EBOV protein VP30. Upon VP30-RadA-ZsG expression from the viral genome, RadA-ZsG is removed from VP30 through the protein splicing activity of RadA, generating functional, non-tagged VP30 and functional ZsGreen. While incorporation of our VP30-RadA-ZsG fusion reporter into recombinant EBOV (rEBOV- RadA-ZsG) resulted in an …

Functional Analysis Of Ligand Binding Domain 2 Of Outer Surface Protein C Of Borreliella Burgdorferi, Gavin Z. Chambers

Theses and Dissertations

Lyme disease, caused by the spirochete Borreliella burgdorferi, is the most common vector-borne infection in North America. A critical determinant of early mammalian infection is outer surface protein C (OspC), a highly variable lipoprotein that is indispensable for spirochete survival but whose precise function remains unresolved. OspC has been proposed to mediate diverse roles, including complement evasion, adhesion, tissue dissemination, and antiphagocytic activity, supporting the view that it is a multifunctional virulence factor. Structural studies have identified two putative ligand-binding domains (LBD1 and LBD2), with LBD2 forming a solvent-exposed crown at the membrane-distal end of the OspC dimer.

To …

The Role Of Horizontal Gene Transfer In Antibiotic Resistance Amidst Prevalent Community And Healthcare-Associated Mrsa Rates, Gabrielle Nascimento

Honors College Theses

In recent decades, cases of community-acquired MRSA (CA-MRSA) and healthcare-associated MRSA (HA-MRSA) have been on the rise. The ability of antibiotic resistance to transfer between microorganisms greatly expands its threat to the effective treatment and containment of bacterial infections. The mecA gene is found on a mobile cassette within the Staphylococcal cell and encodes for PBP2a, an alternate version of penicillin-binding protein (PBP) with less binding affinity for β-lactam antibiotics, increasing resistance to the effects of antibiotics. The goal of this research is to investigate the horizontal transfer of the mecA gene between various Staphylococcus species as well as to …

Biochemical And Molecular Analysis Of Anr-Dependent Microoxic Fitness Factors In Pseudomonas Aeruginosa, Stacie E. Balsam

Dartmouth College Ph.D Dissertations

Pseudomonas aeruginosa is a prominent opportunistic pathogen that is often found in microoxic environments like sites of infection and colony biofilms. P. aeruginosa can grow at oxygen (O2) at concentrations as little as 3 μM and also grows anaerobically by generating energy using nitrate as an alternate electron acceptor. An important way P. aeruginosa adapts to low O2 is through Anr, a transcription factor that upregulates many genes important for microoxic and anoxic fitness.

Specifically, Anr regulates mhr which encodes a hemerythrin protein (Mhr) that binds O2 with affinities relevant to microoxia and is also necessary for full fitness of …