Poly(3-hydroxybutyrate)-P(3HB): Review of Production Process Technology

For decades, conventional plastics obtained from fossil-based sources have been used indiscriminately due to their durability and resistance. However, their use is problematic because of their rapid disposability and slow degradation. Growing scientific interest in the environmental issues associated with rising plastics consumption has become of increasing importance in the search for biodegradable substitutes. Poly (3-hydroxybutyrate) (P(3HB)) is one of the most studied and characterized microbial biopolymers from the family of polyhydroxyalkanoates (PHAs). Its main features are rapid biodegradability, low toxicity, and biocompatibility. Global production of PHAs is approximately 100 tons/year, and is expected to grow to 500,000 tons/year by 2020. Researchers have sought to increase the intracellular accumulation and polymer yield of PHAs by screening strains and improving the cultivation and operating procedures employed during the production processes. Synthesis of P(3HB) normally involves two stages. The first step occurs under growing conditions without nutrient limitation. The second step, polymer production, occurs under conditions in which some of the essential nutrients, such as P, Fe, Mg, and C, are limited and carbon is excessive. This review presents an overview of the metabolic mechanisms of synthesis, production process, recovery and applicability of P(3HB)-related microorganisms as potential producers. It also highlights studies on the optimization of carbon and nitrogen sources in the culture medium and operational parameters that optimize the bioprocess used to obtain P(3HB), both at laboratory- and industrial-scale.