Biopolyester (PHB) obtaining by fermentation of Ralstonia eutropha

Abstract

Nowadays, the dependence that our society has to non-biodegradable plastics derived from petroleum has created the necessity to develop an economically viable alternative. Biopolymers seem to be an attractive alternative to common plastics. Among all them, Polyhydroxyalkanoates (PHA) represent one of the most studied and important source of biopolymers. These biopolymers are produced naturally by various microorganism that use different nutrient sources to conduct the production. Many studies are focusing their efforts in the utilization of alternative substrates to reduce the final cost of the whole process. Besides, the utilization of transgenic organisms (obtained through genetic engineering techniques) for biopolymers production seems to be the path to follow for a higher PHA production and to diminish the cost of the whole biosynthesis. Bearing in mind all this information, in the present thesis, a work to study all the different aspects that involve the obtaining of PHB through fermentation in Ralstonia eutropha was carried out. Hence, the thesis pretends to evaluate experimentally the obtaining, isolation and characterization of PHB in Ralstonia eutropha using different configurations and systems. All these experimental stages were carried out in Terrassa and Barcelona (UPC). Besides, this study includes a theoretical part where all the aspects referred to PHB are analyzed and supports the experimental work carried out. During the experimental part, three different fermentations with Ralstonia eutropha were conducted. The main aim of these fermentations was to see the effect of time and glucose dosage in a fermentative process considering an initial medium –according to literature- as standard. In all these processes, an extraction method with chloroform was used to isolate the final biopolymer. Afterward, a characterization of the product obtained by means of FTIR, NMR and GPC analysis was carried out. All these results are presented in the corresponding section. Besides, in the thesis, an economic study is included in the appendix section. This study comprises the economic cost that is required to develop the PHB process described in the experimental part. Thus, the economic cost, the income and the budget of all the different aspects of the process are considered.