Production of polyhydroxybutyrate (PHB) by cereibacter sphaeroides O.U. 001, rhodopseudomonas palustris 7850 and cupriavidus necator h16 grown in acetate medium and characterization of produced polymers

The increase in population in the world, the decrease in non-renewable resources, the increase of plastic products that are a part of our daily life, and the environmental pollution caused by the fact that petroleum-derived plastics do not die in nature are among the current problems. Polyhydroxybutyrate (PHB), a thermoplastic polymer with biocompatible, degradable and renewable properties, has many of the properties of conventional plastics. This biopolymer is suitable as an alternative to synthetic carbon-based polymers. It is synthesized by different microorganisms such as Alcaligenes, Rhodobacter, Bacillus, Rhizobium, Pseudomonas. Polymer biosynthesis takes place with the realization of enzymatic steps as the assembly and synthesis of monomers. The biosynthesis of polyhydroxybutyrate (PHB) is provided by β-ketothiolase, acetoacetyl-CoA, PHB polymerase/synthase enzymes and phbA, phbB, phbC genes. PHB is broken down by bacteria, microorganisms and fungi in the soil under appropriate conditions, releasing carbon dioxide, energy and water. Due to its biodegradable feature, it is used in many fields such as medicine, agriculture, textile and packaging. Costs can be reduced when appropriate substrate and nutrient medium are used in production. The growth and PHB production of Cereibacter sphaeroides, Rhodopseudomomas palustris and Cupriavidus necator in ammonium medium limited with 70 mM acetate 2 mM were examined. The acetate ratio was determined by looking at their optical densities (OD) in 10, 25, 40, 55, 70, 85 and 100 mM medium. OD values of 4.3, 5.7 and 3.0, pH values of 9.6, 9.8 and 9.1, respectively, were measured in C. sphaeroides, R. palustris and C. necator in 70 mM acetate medium. PHB granules were detected with lipophilic dyes such as Sudan Black B and Nile red. When the Sudan Black B staining was examined under the light microscope, colors between purple, blue and black were observed according to the PHB concentration in the bacteria. When viewed under a fluorescence microscope with Nile red, a red glow in the form of small dots was observed. When PHB was extracted with chloroform, which is the best solvent, 14.6 mg of C. sphaeroides, 31.1 mg of R. palustris, and 5.4 mg of PHB of C. necator were weighed. When the PHB yield was examined, respectively, in bacteria; C. sphaeroides 0.054%, R. palustris 0.11%, C. necator 0.034%. The highest level of PHB production in acetate medium was reached in R. palustris. PHB characterization was made by nuclear magnetic resonance (NMR) spectroscopy method, it was determined that pure PHB was obtained from C. sphaeroides and R. palustris bacteria, PHB obtained from C. necator was not pure compared to other bacteria and there were some impurities. Within the scope of this study, PHB production in acetate medium in C. sphaeroides, R. palustris and C. necator and PHB yield as a result of production were investigated.