Juan C. Higuita

Valorization of glycerol through the production of biopolymers: The PHB case using Bacillus megaterium

In this work technical and economic analyses were performed to evaluate the glycerol transformation into Polyhydroxybutyrate using Bacillus megaterium. The production of PHB was compared using glycerol or glucose as substrates and similar yields were obtained. The total production costs for PHB generation with both substrates were estimated at an industrial scale. Compared to glucose, glycerol showed a 10% and 20% decrease in the PHB production costs using two different separation schemes respectively. Moreover, a 20% profit margin in the PHB sales price using glycerol as substrate resulted in a 166% valorization of crude glycerol. In this work, the feasibility of glycerol as feedstock for the production of PHB at laboratory (up to 60% PHB accumulation) and industrial (2.6US

Biosynthesis of PHB from a new isolated Bacillus megaterium strain: Outlook on future developments with endospore forming bacteria

/kgPHB) scales is demonstrated.

Use of residual banana for polyhydroxybutyrate (PHB) production: case of study in an integrated biorefinery.

Diverse Bacillus strains are known as producers of polyhydroxyalkanoates (PHAs) under nutrient-limiting conditions. However, these limiting conditions have the same nutritional characteristics that stimulate spore generation in Gram-positive microorganisms. In the present work, a new isolated Bacillus megaterium strain was characterized based on 16S rRNA gene sequences (1,411 bp) and studied in terms of its ability for producing polyhydroxybutyrate (PHB) by implementing different fermentation configurations on formulated media. The isolated strain was able to produce PHB up to 59 and 60% of its dry cell weight during bioreactor experiments employing glucose and glycerol as carbon source, respectively. The produced biopolymer was characterized and identified by using carbon-13 nuclear magnetic resonance (13C-NMR) and Fourier transform infrared (FTIR) techniques. In spite of the sporulation phenomenon existing in Bacillus strains, obtained results demonstrate that the new isolated strain has the potential of accumulating high levels of intracellular PHB. Supported by these experimental results and by those reported by other authors, the last section of this paper gives an outlook of future research topics on PHB and polyhydroxyalkanoate (PHA) copolymers production by Gram-positive bacteria. The importance of combining bioprocessing/biorefinering concepts with bioreactor optimization approaches is stressed and analyzed based on current PHAs research trends.

Design and analysis of poly-3-hydroxybutyrate production processes from crude glycerol

Polyhydroxybutyrate is a type of biopolymer that can be produced from hydrolyzed polysaccharide materials and could eventually replace polypropylene and polyethylene, being biodegradable, biocompatible and produced from renewable carbon sources. However, polyhydroxybutyrate is not still competitive compared to petrochemical polymers due to their high production costs. The improvement of the production processes requires a search for new alternative raw materials, design of the pretreatment technique and improvement in the fermentation and separation steps. In addition, if the polyhydroxybutyrate production is coupled into a multiproduct biorefinery it could increase the economic and environmental availability of the process through energy and mass integration strategies. In this work alternatives of energy and mass integrations for the production of polyhydroxybutyrate into a biorefinery from residual banana (an agro-industrial waste) were analyzed. The results show that the energetic integration can reduce up to 30.6% the global energy requirements of the process and the mass integration allows a 35% in water savings. Thus, this work demonstrates that energy and mass integration in a biorefinery is a very important way for the optimal use of energy and water resources hence decreasing the production cost and the negative environmental impacts.