Cell Biology Commons^™

The Effects Of Specialized Pro-Resolving Mediator Lipoxin A4 On Pseudomonas Aeruginosa Biofilms And Interactions With Monocytes, Julianne M. Thornton

Graduate School of Biomedical Sciences Theses and Dissertations

Pseudomonas aeruginosa (P. aeruginosa) is an opportunistic pathogen known as a major cause of hospital-acquired secondary infections, commonly causing chronic respiratory infections in immunocompromised individuals, especially those with cystic fibrosis, and often found in wound infections. P. aeruginosa uses the quorum sensing pathway to readily form protective biofilms, which reduce the efficacy of antibiotics and access by host immune cells to eradicate the pathogen. Specialized pro-resolving mediators (SPMs) are lipids endogenously produced by the host immune response to infection to aid in infection resolution. One SPM, Lipoxin A4 (LxA4), has been shown to be a robust quorum sensing inhibitor.

The …

Investigating The Antibacterial And Immunomodulatory Properties Of Lactobacillus Acidophilus Postbiotics, Rachael M. Wilson

Graduate School of Biomedical Sciences Theses and Dissertations

Probiotics are nonpathogenic microorganisms that have been extensively studied for their ability to prevent various infectious, gastrointestinal, and autoimmune diseases. The mechanisms underlying these probiotic effects have not been elucidated. However, we and other researchers have evidence suggesting that probiotic bacteria secrete metabolites that are antimicrobial and anti-inflammatory. As such, we developed a methodology to collect the secreted metabolites from a probiotic bacterium, Lactobacillus acidophilus, and tested this cell free filtrate (CFF) both in vitro and in vivo. Using this CFF, we have demonstrated that L. acidophilus secretes a molecule(s) that has specific bactericidal activity against the opportunistic pathogen, Pseudomonas …

The 'Pseudomonas Aeruginosa' Psl Polysaccharide Is A Social But Noncheatable Trait In Biofilms, Yasuhiko Irie, Aled E. Roberts, Kasper N. Kragh, Vernita D. Gordon, Jaime B. Hutchison, Rosalind J. Allen, Gavin Melaugh, Thomas Bjarnsholt, Stuart A. West, Stephen P. Diggle

Biology Faculty Publications

Extracellular polysaccharides are compounds secreted by microorganisms into the surrounding environment, and they are important for surface attachment and maintaining structural integrity within biofilms. The social nature of many extracellular polysaccharides remains unclear, and it has been suggested that they could function as either cooperative public goods or as traits that provide a competitive advantage. Here, we empirically tested the cooperative nature of the PSL polysaccharide, which is crucial for the formation of biofilms in Pseudomonas aeruginosa. We show that (i) PSL is not metabolically costly to produce; (ii) PSL provides populationlevel benefits in biofilms, for both growth and antibiotic …

Identification Of Novel Cyclic Lipopeptides From A Positional Scanning Combinatorial Library With Enhanced Antibacterial And Antibiofilm Activities, Nina Bionda, Renee M. Fleeman, César De La Fuente-Núñez, Maria C. Rodriguez, Fany Reffuveille, Lindsey N. Shaw, Irena Pastar, Stephen C Davis, Robert E W Hancock, Predrag Cudic

Molecular Biosciences Faculty Publications

Treating bacterial infections can be difficult due to innate or acquired resistance mechanisms, and the formation of biofilms. Cyclic lipopeptides derived from fusaricidin/LI-F natural products represent particularly attractive candidates for the development of new antibacterial and antibiofilm agents, with the potential to meet the challenge of bacterial resistance to antibiotics. A positional-scanning combinatorial approach was used to identify the amino acid residues responsible for driving antibacterial activity, and increase the potency of these cyclic lipopeptides. Screening against the antibiotic resistant ESKAPE pathogens revealed the importance of hydrophobic as well as positively charged amino acid residues for activity of this class …

Analysis Of The Candida Albicans Phosphoproteome, S. D. Willger, Z. Liu, R. A. Olarte, M. E. Adamo, J E. Stajich, L C. Myers, A N. Kettenbach, D A. Hogan

Dartmouth Scholarship

Candida albicans is an important human fungal pathogen in both immunocompetent and immunocompromised individuals. C. albicans regulation has been studied in many contexts, including morphological transitions, mating competence, biofilm forma- tion, stress resistance, and cell wall synthesis. Analysis of kinase- and phosphatase-deficient mutants has made it clear that pro- tein phosphorylation plays an important role in the regulation of these pathways. In this study, to further our understanding of phosphorylation in C. albicans regulation, we performed a deep analysis of the phosphoproteome in C. albicans. We identified 19,590 unique peptides that corresponded to 15,906 unique phosphosites on 2,896 proteins. The …

Talking To Themselves: Autoregulation And Quorum Sensing In Fungi, Deborah A. Hogan

Dartmouth Scholarship

Extracellular autoinducing compounds in the supernatants of microbial cultures were first recognized for their roles in the induction of genetic competence in gram-positive bacteria and in the regulation of light production in marine vibrios. In 1994, this form of population-level regulation in microbes was dubbed “quorum sensing” since it enabled bacterial cells to chemically measure the density of the surrounding population. Subsequently, many examples of cell density-dependent regulation by extracellular factors have been found in diverse microorganisms. The widespread incidence of diverse quorum-sensing systems strongly suggests that regulation in accordance with cell density is important for the success of microbes …