Hopanoids in Bacteria and Cyanobacteria - Their Role in Cellular Biochemistry and Physiology, Analysis and Occurrence

Hopanoids, widespread compounds of triterpene nature, are found mainly in different bacterial types (G+ and G- bacteria, aerobs, facultative anaerobs, strict anaerobs), in methanotrophs, acetic acid bacteria, nitrogen fixers, purple non-sulphur bacteria, cyanobacteria, and also in sediments. They occur in a variety of structures from simple hopanoids to elongated compounds with polyfunctional side chains such as bacteriohopanepolyols (BH-polyols). This review summarizes current knowledge of the occurrence of these compounds in different bacterial types, genera and species, their biosynthesis and functions in cellular membranes and in important biochemical and physiological processes, and surveys advances and trends in the field of hopanoid analysis, especially as concerns LC-MS with soft ionization techniques such as APCI and/or ESI.