This Volume addresses the pros and cons of oligonucleotide probes, primers and primer combinations, and importantly considers how to design the best tools for the microbial taxa and/or processes being investigated. Individual chapters focus on the design of primers targeting genes that code for enzymes associated with the following functions: degradation of aromatic, aliphatic and chlorinated hydrocarbons under aerobic and anaerobic conditions, methanogenesis, methane oxidation, and the nitrogen cycle. 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 exploitation of useful activities of such microbes.