This Volume covers protocols for various applications in hydrocarbon microbiology, including those of interest for industrial processes, biocatalysis, lipid and biofuel production, bioproducts, or the human microbiome. It presents detailed protocols for the functional screening of enzymes acting on greasy molecules (i.e. lipases, esterases), including assays for enantioselective biocatalysts, as well as approaches for protein display technologies. Protocols for improving fuel quality and production of biofuel and lipids in different hosts (bacteria, algae, yeast) are also provided. The production of biogas from organic waste and its fermentation into value-added products such as polyhydroxyalkanoates is covered, as well as an in-vitro model of the gut microbiome for short-chain fatty acid metabolism and microbial diversity analyses. The applications presented are examples of the many potential applications in hydrocarbon and lipid microbiology, and many (i.e. protein-display technologies) will also be of interest in other research fields. Hydrocarbon and Lipid Microbiology Protocols There are tens of thousands of structurally different hydrocarbons, hydrocarbon derivatives and lipids, and a wide array of these molecules are required for cells to function. The global hydrocarbon cycle, which is largely driven by microorganisms, has a major impact on our environment and climate. Microbes are responsible for cleaning up the environmental pollution caused by the exploitation of hydrocarbon reservoirs and will also be pivotal in reducing our reliance on fossil fuels by providing biofuels, plastics and industrial chemicals. Gaining an understanding of the relevant functions of the wide range of microbes that produce, consume and modify hydrocarbons and related compounds will be key to responding to these challenges. This comprehensive collection of current and emerging protocols will facilitate acquisition of this understanding and exploitationof useful activities of such microbes.