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Characterization Of Antimicrobial Activity Of The Symbiotic Bacterium Xenorhabdus Szentirmaii, Miliya Ansad
Characterization Of Antimicrobial Activity Of The Symbiotic Bacterium Xenorhabdus Szentirmaii, Miliya Ansad
Theses and Dissertations
Xenorhabdus species belonging to the Enterobacteriaceae family are gram negative bacteria that engage in symbiotic associations with the entomopathogenic soil dwelling nematodes of the family Steinernematidae. In this bacterium–nematode mutualistic interaction, both partners benefit from the association. By entering and perforating the insect gut and translocating to the body cavity of hemocoel, the nematodes gain access to the nutrient resource of the insect hemolymph. Xenorhabdus spp are released in the hemolymph in which they produce toxins and immunosuppressive compounds that kill the insect. During the infection Xenorhabdus spp grow to high cell density in the hemolymph. As the nematode invades …
Structural And Functional Characterization Of L-Enduracididine Biosynthetic Enzymes, Nemanja Vuksanovic
Structural And Functional Characterization Of L-Enduracididine Biosynthetic Enzymes, Nemanja Vuksanovic
Theses and Dissertations
The mannopeptimycins produced by Streptomyces hygroscopicus are non-ribosomal peptide antibiotics with activity against a number of Gram-positive pathogens, including drug-resistant strains like methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE). Attempts to synthesize more potent mannopeptimycin analogues have so far not been successful. One reason this has proven difficult is that the mannopeptimycins contain the unusual non-proteinogenic amino acid L-enduracididine (L-End), or its hydroxylated derivative β-hydroxy enduracididine (βhEnd,). This amino acid is not commercially available and, while synthetic routes have been developed, they are multi-step processes starting from an advanced intermediate. Understanding enzymatic synthesis of L-End is an important goal, …
New Insights Into The Role Of Antimicrobials Of Xenorhabdus In Interspecies Competition, Kristin Jean Ciezki
New Insights Into The Role Of Antimicrobials Of Xenorhabdus In Interspecies Competition, Kristin Jean Ciezki
Theses and Dissertations
Xenorhabdus spp. are symbionts of entomopathogenic nematodes and pathogens of susceptible insects. The nematodes penetrate the insect midgut to enter the hemocoel where Xenorhabdus bacteria are released, transitioning to their pathogenic stage. During nematode invasion microbes from the insect gut translocate into the hemocoel. In addition, different species of nematodes carrying specific strains of Xenorhabdus can invade a single insect. Xenorhabdus spp thereby engage in competition with both related strains and nonrelated gut microbes. In complex media Xenorhabdus spp produce diverse antimicrobial compounds whose functions in biological systems remain poorly understood. R-type bacteriocins are contractile phage-tail-like structures that are bactericidal …