Aliphatic Hydrocarbons

Aliphatic compounds are carbon and hydrogen-containing hydrocarbon complexes and are present in almost every plant, animal and microorganism. In 1929, aliphatic hydrocarbons were first discovered by crude chemical methods. These observations were later confirmed and expanded by more sophisticated instruments, such as gas-liquid chromatography and GLC-mass spectrometry. Aliphatic hydrocarbons were detected in the wax of most studied organisms and mainly contained n-alkanes, but may also include n-alkenes, saturated and unsaturated, cyclic alkanes, and isoprenoid hydrocarbons. Similarly, surfaces of higher plants contain a complex waxy coating that consists of primary and secondary fatty alcohols, long chains of fatty acids, ketones, aldehyde, terpenes, diols, waxy esters, glycerides, etc. The chemical composition of aliphatic hydrocarbons, chain length predominance, branching, the unsaturation of surface wax and their variation among various organisms, such as plants, algae, bacteria, animals and particularly in fungi have been described in the current chapter. The hydrocarbon distribution in animals is reported to be slightly similar to that of higher plants, while in bacteria, a complex mixture of normal, single- double branched, saturated, or unsaturated structural isomers are reported. A brief description of the biotechnological production of various aliphatic compounds using genetic engineering has also been presented in this chapter. The biosynthesis of aliphatic hydrocarbons by two common routes, “elongation decarboxylation” and “head-to-head condensation,” has been studied well in plants and bacteria and are discussed here in detail. Pathways involved in the degradation of hydrocarbons by aerobic and anaerobic microbes and the enzymes involved are also described in this chapter. Aliphatic compounds with different chain lengths have been of biotechnological interest for the past few decades as they perform various biological functions in living organisms apart from their role as the chief component of diesel and jet fuels. The current chapter also highlighted the biological importance of these aliphatic hydrocarbons.