Drug Discovery from Cold-Adapted Bacteria from Malpeque Bay, Prince Edward Island

Marine bacteria represent an excellent renewable source of novel, bioactive natural products. Cold-adapted bacteria have been under-studied and thus temperate environments represent a largely untapped resource for the discovery of microbial natural products.

This thesis examined the bacterial diversity of cold-adapted bacteria from seawater and sediment collected from Malpeque Bay, Prince Edward Island, a unique marine environment, which resulted in the discovery of 16 different groups of bacteria. One isolate was fermented from each group in 11 different media, in a high-throughput method using 96-well plates to maximize the number of media conditions used for each isolate. LC-MS analysis was performed on crude extracts and follow-up fermentations were prioritized by LC-MS data analysis. Fermentations of 6 isolates in 2 media were scaled up in 24-well plates and in 250 mL Erlenmeyer flasks for production confirmation and antimicrobial analysis. A psychrotolerant bacterium, Figoribacterium sp., was found to produce a wide variety of cell-associated glycoglycerolipids (GGL) in ACC media. Four glycoglycerolipids, 1-O-acyl-3-[α-D-mannopyranosyl-(1-3)-(6-O-acyl-α-D-mannopyranosyl)]-sn-glycerol (GGL 915, 887, 885a and 885b), including two new analogues which contain trans-12-methyl-10-tetradecenoic acid and 12-methyltetradecanoic acid were isolated by reverse phase chromatography.

Structure elucidation was performed by LC-ESI-MS/MS, HR-MS and NMR. NMR characterization involved the use of 1D NMR (1H and 13C), 2D NMR (COSY, HSQC, HMBC, NOESY and ROESY) as well as coupling constant analysis. Fermentation optimization by supplementing ACC media with 20 g/L glucose or glycerol greatly increased production of different GGL analogues. One of the new compounds, GGL 915, was assessed for surface tension, antimicrobial and cytotoxic activities and was found to be inactive. However, GGL 885, 887 and 915 were tested for activity against the Vaccinia and Influenza A viruses, where GGL 887 showed preliminary indications of antiviral activity against Influenza A.