Bacterial volatiles and their action potential.

During the past few years, an increasing awareness concerning the emission of an unexpected high number of bacterial volatiles has been registered. Humans sense, intensively and continuously, microbial volatiles that are released during food transformation and fermentation, e.g., the aroma of wine and cheese. Recent investigations have clearly demonstrated that bacteria also employ their volatiles during interactions with other organisms in order to influence populations and communities. This review summarizes the presently known bioactive compounds and lists the wide panoply of effects possessed by organisms such as fungi, plants, animals, and bacteria. Because bacteria often emit highly complex volatile mixtures, the determination of biologically relevant volatiles remains in its infancy. Part of the future goal is to unravel the structure of these volatiles and their biosynthesis. Nevertheless, bacterial volatiles represent a source for new natural compounds that are interesting for man, since they can be used, for example, to improve human health or to increase the productivity of agricultural products.