Marinobacter Aquaeolei VT8 As a Model for the Production of High-Value Neutral Lipids in Bacteria

The study of biological pathways utilized to produce and accumulate energy storage compounds such as fats and oils has tremendous importance towards pursuing new routes in the production of sustainable fuels and new bioproducts to meet growing energy and production demands. Wax esters, the product of the esterification of a fatty acid and a fatty alcohol, are a highly valued class of neutral lipid utilized in cosmetics, pharmaceuticals, as fine lubricants, and potentially as fuels. Most commercial wax esters are synthesized from fossil fuels, and thus there is a growing interest in developing biological systems for the sustainable production of wax esters. Our laboratory has evaluated several strains of bacteria, including Marinobacter, Acinetobacter, Rhodococcus and Psychrobacter as potential models for both whole-cell systems analysis, and also as sources for enzymes for in vitro laboratory studies, and based on a number of factors, have chosen Marinobacter aquaeolei VT8 as an ideal model system for the study of wax ester production in a bacterium. Our characterization of key enzymes from this species have found enzyme activities that are several orders of magnitude higher than previously characterized enzymes from other sources, and have also revealed key kinetic features of these enzymes that would be pertinent factors to consider in biosynthetic design approaches. Theoretical models of these enzymes have enabled us to probe potential residues surrounding the active sites, and revealed key residues with a role in determining substrate specificity. Whole cell analysis, including RNA-seq studies of changes in transcription during the wax ester accumulation and degradation curve provide a unique look at how this bacterium regulates the production of genes involved in the wax ester production pathway, providing clues for potential efforts to improve lipid production in a bacterium that has evolved to naturally accumulate a neutral lipid. Recent results from enzyme studies, gene deletion experiments and transcriptional profiling of the entire genome are presented.