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International Journal of Polymer Science
Volume 2019, 2019, Pages 1-7

A Process Engineering Approach to Improve Production of P(3HB) by Cupriavidus necator from Used Cooking Oil

Madalena V. Cruz1, Ana Rosa Gouveia1, Madalena Dionísio2, Filomena Freitas1, and Maria A. M. Reis1

UCIBIO-REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Campus de Caparica, 2829-516 Caparica, Portugal.

Abstract

Different feeding strategies, namely, exponential feeding and DO-stat mode, were implemented for the production of poly(3-hydroxybutyrate), P(3HB), by Cupriavidus necator DSM 428 with used cooking oil (UCO) as the sole carbon source. With the exponential feeding strategy, a cell dry mass of 21.3±0.9gL-1 was obtained, with a polymer content of 84.0±4.5wt.%, giving an overall volumetric productivity of 4.5±0.2gL-1 day-1. However, the highest P(3HB) volumetric productivity, 12.6±0.8gL-1 day-1, was obtained when the DO-stat mode was implemented together with the use of ammonium hydroxide for pH control, which served as an additional nitrogen source and allowed to reach higher cell dry mass (7.8±0.6gL-1). The P(3HB) obtained in all experiments had a high molecular mass, ranging from 0.6×105 to 2.6×105 gmol-1, with low polydispersity indexes of 1.2-1.6. Melting and glass transition temperatures were also similar for the polymer produced with both cultivation strategy, 174°C and 3.0-4.0°C, respectively. The polymer exhibited a crystallinity ranging from 52 to 65%. The DO-stat strategy to feed oil containing substrates as the sole carbon sources was reported for the first time in this study, and the preliminary results obtained show that it is a promising strategy to improve P(3HB) production. Nevertheless, the process requires further optimization in order to make it economically viable.

 

 
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