Biosynthetic Gene Clusters, Microbiomes, and Secondary Metabolites in Cold Water Marine Organisms

• Main Author: Avalon, Nicole Elizabeth
• Format: Doctoral or Postdoctoral Thesis
• Language: unknown
• Published: Digital Commons @ University of South Florida 2020
• Subjects: Antarctica; Ascidian; Cnidaria; Deep-Sea Ireland; Host-Associated Bacteria; Marine Natural Products; Chemistry; Antarctic; The Antarctic; Antarc*
• Online Access: https://digitalcommons.usf.edu/etd/9524; https://digitalcommons.usf.edu/cgi/viewcontent.cgi?article=10721&context=etd

Microorganisms and invertebrate animals from cold water marine environments, such as in Antarctica and in Ireland’s deep sea, are a rich source of secondary metabolites. In this dissertation, research was centered around secondary metabolism and natural product biosynthesis. The projects include the delineation of biosynthetic gene clusters hypothesized to be responsible for the biosynthesis of the palmerolides, stratification of the microbiome of the Antarctic ascidian Synoicum adareanum, genomic and peptidomic analysis of a host-associated Antarctic Pseudovibrio sp., and isolation and characterization of secondary metabolites from the Irish deep-sea coral Drifa sp. Palmerolide A, the principle secondary metabolite associated with S. adareanum, is a potent V-ATPase inhibitor with selectivity for malignant melanoma cell lines; however, drug development efforts have not been feasible due to a lack of supply. Identification of the producing organism and of the biosynthetic gene cluster could solve the supply issue through biotechnological methods of heterologous gene expression and large scale microbial cultivation efforts. The putative biosynthetic gene cluster responsible for palmerolide A production has now been identified and delineated in a host-associated bacterium. The biosynthetic gene cluster is a hybrid Type-I PKS/NRPS with several interesting non-canonical features, including a truncated condensation termination domain, a luciferase-like monooxygenase that is hypothesized to play a biosynthetic role as a hydroxylase, and a HMG-CoA synthetase cassette that installs a β-branch. Additionally, five variants of the pal biosynthetic gene cluster were identified, some of which explain the architectural diversity seen in the family of palmerolides. The microbiome of S. adareanum was stratified through statistical analysis in efforts to identify the microbial producer of palmerolide A. A suite of ecological statistics was used for analysis of the ASV occurrence data. Twenty-one amplicon sequence variants (ASVs) ...