Alkaline organic compounds with an aliphatic, satu­rated carbon backbone having at least two primary amino groups, and a varying number of secondary amino groups are referred to as polyamines (Schneider and Wendisch, 2011). The polyamines were first discov­ered by Antonie van Leeuwenhoek (1678) when he iso­lated some "three-sided" crystals (sperminephosphate crystals) from human semen. The charge on the poly­amines is distributed along the entire length of the car­bon chain, making them unique and distinct from the point charges of the cellular bivalent cations. Their pos­itive charge enables polyamines to interact electrostati­cally withpolyanionicmacromolecules within the cell. Due to this they can modulate diverse cellular processes such as transcription and translation (Wallace et al.,

2003) , biosynthesis of siderophores (Brickman and

Armstrong, 1996), take part in acid resistance (Foster,

2004) , protect from oxygen toxicity (Jung et al., 2003), etc. They have a role in signaling for cellular differentia­tion (Sturgill and Rather, 2004) and are essential for pla­que biofilm formation (Patel et al., 2006). They are also found as a part of gram-negative bacterial outer mem­branes (Takatsuka and Kamio, 2004). Transgenic activa­tion of polyamine catabolism profoundly disturbs polyamine homeostasis in most tissues, creates a com­plex phenotype affecting skin, female fertility, fat de­pots, pancreatic integrity and regenerative growth (Janne et al., 2004). In the nucleosome, polyamine deple­tion results in partial unwinding of DNA and unmask­ing of sequences previously buried in the particle. These sequences are potential binding sites for factors regulating transcription (Morgan et al., 1987). This, together with the fact that polyamines favor the forma­tion of triplex DNA at neutral pH, may provide a mech­anism whereby polyamines regulate the transcription of growth regulatory genes such as c-myc (Hampel et al., 1991; Celano et al., 1992). Since polyamines play a wide range of activities in a living cell their relative intracellular concentrations may vary from species to species, and they can reach up to the millimolar range (Miyamoto et al., 1993).

The most common polyamines in bacteria and Archaea are putrescine (a diamine also named as

1,4- diaminobutane) and cadaverine (diamine also named 1,5-diaminopentane) (Figure 19.3). In addition to the above-mentioned polyamines, the pathways for the biosynthesis of 1,3-diaminopropane, norspermidine, homospermidine, and thermine are known in some bac­teria and Archaea (Tabor and Tabor, 1985). The poly­amine family also contains a number of uncommon longer or branched-chain polyamines, which were found in extremophiles and which seem to play an essential role for growth under such extreme conditions (Oshima, 2007). Polyamines are found in all living spe­cies, except two orders of Archaea, Methanobacteriales and Halobacteriales (Hamana and Matsuzaki, 1992).

Polyamines are used in a wide variety of commercial applications due to their unique combination of reactivity, basicity, and surface activity. With a few exceptions, they are used predominantly as intermediates in the produc­tion of functional products (e. g. polyamides/epoxy curing, fungicide, anthelmintics/pharmaceuticals, petro­leum production, oil and fuel additives, paper resins, chelating agents, fabric softeners/surfactants, bleach acti­vator, asphalt chemicals) (Kroschwitz and Seidel, 2004). The main commercial interest in biogenic polyamines is their use in the polymer industry. Today, the only example of an industrial polyamide containing a biogenic diamine, which can also be synthesized by bacteria, is nylon-4, 6. This polyamide is produced from putrescine and adipic acid (hexanedioic acid).