Comparison of microbial communities in Lake Tahoe surface sample with Tonga Trench water column samples using High Pressure Liquid Chromatography - Electrospray Ionization - Mass Spectroscopy (HPLC - ESI - MS) and Global Natural Products Social Molecular Network (GNPS)

Abstract:

Intact polar lipids (IPLs) are lipids composed of a head group, a glycerol, and a fatty acid chain that make up the lipid bilayer of cell membranes in living cells; and the varying head groups can be indicative of the type of microbes present in the environment (Van Mooy 2010). So by distinguishing and identifying the IPL distribution in an environment one can make inferences about the microbial communities in the said environment. In this study, we used High Pressure Liquid Chromatography-Electrospray Ionization- Mass Spectroscopy (HPLC-ESI-MS) and Global Natural Products Social Molecular Networking (GNPS) to compare the IPL distributions of two oligotrophic environments: surface waters of Lake Tahoe in the Sierra Nevada Mountains, and the water column of the Tonga Trench in the South Pacific. We hypothesized that the similar nutrient dynamics of the two oligotrophic environments would result in similar eukaryotic and prokaryotic communities, which would be reflected in the IPL composition of suspended particulate organic matter (POM). For simplicity we focused on the classes of IPLs most commonly observed in the marine environment: phosphotidylglycerol (PG), phosphotidylethanolamine (PE), diacylglyceryl-trimethyl-homoserine (DGTS), diacylglyceryl-hydroxymethyl-trimethylalanine (DGTA), sulfoquinovosyldiacylglycerol (SQDG), monoglycosyldiacylglycerol (MGDG) and diglycosyldiacylglycerol (DGDG). Our results showed that all of the marine IPLs of interest were present in Lake Tahoe which confirms that there are many of the same microbial communities in the fresh waters of Lake Tahoe and the salt waters Tonga Trench.