Determination of Nutritional and Operational Conditions for the Production of Polyhydroxybutyrate by Halomonas boliviensis

Abstract

ABSTRACT: The production of biopolymers is being supported worldwide given the environmental impacts and consciousness regarding the abusive use of conventional synthetic plastics. Polyhydroxyalcanoates (PHAs) are biobased and biodegradable biopolymers that are of particular interest given their outstanding properties and carbon footprint, that enable them to be a suitable replacement to plastics. The most studied PHA is the polyhydroxybutyrate (PHB), a short chain length PHA with a broad application field due to its physical and thermal properties alike polyethylene, making it useful in the packaging industry and biocompatible non-toxic properties availing its use in biomedical applications. Despite the benefits provided by this biopolymer, its production at industrial scale is expensive making them uncompetitive or unfeasible respect to petrochemical plastics. Improvements and optimizations must be made to the fermentation process to reduce the costs associated with the production. In this work, the study of nutritional and operational conditions to favor the production of PHB by Halomonas boliviensis using an inexpensive substrate was carried out. The development of this work is presented in four chapters that comprise the overall objective of the research. The first chapter covers the introduction to the topic from the research problem, to the theoretical frame and state of the art leading to understanding what took us to perform this research work. The second chapter contains the first objective, which was to evaluate three inexpensive alternative nitrogen sources on cell growth, PHB production using Halomonas boliviensis considering that is the most expensive constituent of culture media per Kg, and that its cost affects the production economics. In the third chapter, the effect of dissolved oxygen concentrations at bioreactor scale on cell growth and PHB content attained by Halomonas boliviensis was studied to fulfill the second objective. The fourth chapter shows the construction of an unstructured model and parameter estimation of polyhydroxybutyrate production by Halomonas boliviensis.