11.1.1 Scientific Achievements

The presence of what were initially assumed to be lipid inclusions in bacteria was first mentioned in the literature one century ago [1]. Granule inclusions inside Bacillus megaterium were characterised in greater detail by Lemoigne only twenty years later [2-5]. More specifically, Lemoigne demonstrated that this intracellular material was a polyester having the formula (C ₄H ₆O ₂) _n, and named it acide ?-oxybutyrique . Today, this polyester is commonly called poly(3-hydroxybutyric acid) (PHB) and it belongs to the polyhydroxyalkanoate family (PHA).

Over the next few decades, academic research brought a greater understanding of this particular phenomenon. Thus, by the end of the 1950s it was clearly evident that intracellular bacterial inclusions were a form of carbon energy storage [6-8]. More importantly, it was then well understood that their accumulation can be enhanced by limiting the supply of nitrogen in the growth medium while providing an excessive carbon source [8]. In addition, the storage of PHB as energy material was reported to be a widespread phenomenon occurring mainly in Gram-negative bacteria [9]. In 1974, the existence of hydroxyalkanoate monomer units other than 3-hydroxybutyric acid (3HB) was reported by Wallen and Rohwedder [10]. The new hydroxyalkanoate monomer unit found was a 3-hydroxyvalerate (3HV), while a minor constituent, 3-hydroxyhexanoate (3HHx), was also reported. Since then, other authors have reported additional monomer units such as 3-hydroxyheptanoate (3HHp) [11] and 3-hydroxyoctanoate (3HO) [12]. To date, more than...